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ENERGY (180 journals)                  1 2 | Last

Advances in Building Energy Research     Hybrid Journal   (Followers: 11)
Advances in Energy and Power     Open Access   (Followers: 2)
Advances in High Energy Physics     Open Access   (Followers: 12)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 14)
American Journal of Energy Research     Open Access   (Followers: 6)
Annals of Nuclear Energy     Hybrid Journal   (Followers: 7)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 1)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 11)
Applied Nanoscience     Open Access   (Followers: 10)
Applied Solar Energy     Hybrid Journal   (Followers: 12)
Archives of Thermodynamics     Open Access   (Followers: 4)
Artificial Photosynthesis     Open Access  
Atomic Energy     Hybrid Journal   (Followers: 5)
Atoms for Peace: an International Journal     Hybrid Journal   (Followers: 3)
Biofuels     Hybrid Journal   (Followers: 8)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
Bulletin de droit nucleaire     Full-text available via subscription   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Carbon Management     Hybrid Journal   (Followers: 6)
Catalysis for Sustainable Energy     Open Access   (Followers: 2)
CERN courier. International journal of high energy physics     Free  
Chain Reaction     Full-text available via subscription  
Clefs CEA     Full-text available via subscription   (Followers: 1)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 2)
Continental Journal of Renewable Energy     Open Access   (Followers: 11)
Current Sustainable/Renewable Energy Reports     Hybrid Journal   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Development of Energy Science     Open Access   (Followers: 3)
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (Followers: 1)
E3S Web of Conferences     Open Access  
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 3)
Electrical and Power Engineering Frontier     Open Access   (Followers: 9)
Electronic Journal of Energy & Environment     Open Access   (Followers: 9)
Energy     Partially Free   (Followers: 26)
Energy & Fuels     Full-text available via subscription   (Followers: 25)
Energy and Buildings     Hybrid Journal   (Followers: 7)
Energy and Environment Research     Open Access   (Followers: 9)
Energy and Environmental Engineering     Open Access  
Energy and Power     Open Access   (Followers: 3)
Energy and Power Engineering     Open Access   (Followers: 10)
Energy Conversion and Management     Hybrid Journal   (Followers: 8)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 1)
Energy Journal The     Full-text available via subscription  
Energy Law Journal     Full-text available via subscription   (Followers: 2)
Energy Policy     Partially Free   (Followers: 47)
Energy Prices and Taxes     Full-text available via subscription   (Followers: 5)
Energy Procedia     Open Access   (Followers: 3)
Energy Research & Social Science     Full-text available via subscription  
Energy Science & Engineering     Open Access   (Followers: 4)
Energy Science and Technology     Open Access   (Followers: 12)
Energy Strategy Reviews     Partially Free   (Followers: 6)
Energy Studies Review     Open Access   (Followers: 4)
Energy Systems     Hybrid Journal   (Followers: 10)
Energy Technology     Partially Free   (Followers: 3)
Energy, Sustainability and Society     Open Access   (Followers: 18)
Environmental Progress & Sustainable Energy     Hybrid Journal   (Followers: 4)
EPJ Photovoltaics     Open Access   (Followers: 1)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Renewable Energy     Full-text available via subscription   (Followers: 1)
Frontiers in Energy     Hybrid Journal   (Followers: 4)
Frontiers in Energy Research     Open Access   (Followers: 1)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 5)
Functional Materials Letters     Hybrid Journal   (Followers: 1)
Gcb Bioenergy     Hybrid Journal   (Followers: 3)
Geothermal Energy     Open Access   (Followers: 1)
GeoWorld     Full-text available via subscription   (Followers: 2)
Green     Full-text available via subscription   (Followers: 2)
IEA Electricity Information     Full-text available via subscription   (Followers: 5)
IEA Natural Gas Information     Full-text available via subscription   (Followers: 4)
IEEE Power and Energy     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 6)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 7)
IEEE Transactions on Power Systems     Hybrid Journal   (Followers: 10)
IET Power Electronics     Hybrid Journal   (Followers: 10)
Ingeniería Energética     Open Access  
Innovations : Technology, Governance, Globalization     Hybrid Journal   (Followers: 6)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 1)
International Journal of Ambient Energy     Hybrid Journal   (Followers: 2)
International Journal of Applied Power Engineering     Open Access   (Followers: 2)
International Journal of Clean Coal and Energy     Open Access   (Followers: 4)
International Journal of Coal Science & Technology     Open Access  
International Journal of Critical Infrastructure Protection     Hybrid Journal   (Followers: 5)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 5)
International Journal of Emerging Electric Power Systems     Full-text available via subscription   (Followers: 5)
International Journal of Emerging Multidisciplinary Fluid Sciences     Full-text available via subscription  
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 2)
International Journal of Energy and Power     Open Access   (Followers: 7)
International Journal of Energy Engineering     Open Access   (Followers: 12)
International Journal of Energy Research     Hybrid Journal   (Followers: 10)
International Journal of Energy Science     Open Access   (Followers: 1)
International Journal of Flow Control     Full-text available via subscription   (Followers: 2)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 6)
International Journal of Green Energy     Hybrid Journal   (Followers: 6)
International Journal of Hydrogen Energy     Partially Free   (Followers: 12)
International Journal of Marine Energy     Full-text available via subscription   (Followers: 2)
International Journal of Nuclear Desalination     Hybrid Journal   (Followers: 2)
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (Followers: 2)
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal   (Followers: 2)

        1 2 | Last

Journal Cover   Functional Materials Letters
  [SJR: 0.451]   [H-I: 12]   [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1793-6047 - ISSN (Online) 1793-7213
   Published by World Scientific Homepage  [114 journals]
  • Generalized Hamiltonian for a graphene subjected to arbitrary in-plane
    • Authors: Biao Wang, Yunhua Wang, Yulan Liu
      Abstract: Functional Materials Letters, Ahead of Print. The interplay between the linear elastic deformation up to 20% and the unique electronic properties of graphene nanostructures offers an attractive prospect to manipulate their properties by strain. Here we review the recent progress on the electronic response of graphene to the in-plane strains, including the strain-modulated electronic structure and the strain-modulated spin, valley and superconducting transports. A generalized Hamiltonian for a graphene was constructed subjected to arbitrary in-plane strains. The Hamiltonian is helpful to design and optimize the graphene-based nano-electromechanical systems (NEMS).
      Citation: Functional Materials Letters
      PubDate: Fri, 06 Feb 2015 01:36:36 GMT
      DOI: 10.1142/S1793604715300017
  • Ferritin-mediated biomimetic synthesis of bimetallic Au–Ag
           nanoparticles on graphene nanosheets for electrochemical detection of
           hydrogen peroxide
    • Authors: Li Wang, Jiku Wang, Pengjuan Ni, Zhuang Li
      Abstract: Functional Materials Letters, Ahead of Print. We demonstrated a biomimetic green synthesis of bimetallic Au–Ag nanoparticles (NPs) on graphene nanosheets (GNs). The spherical protein, ferritin (Fr), was bound onto GNs and served as the template for the synthesis of GN/Au–Ag nanohybrids. The created GN/Au–Ag nanohybrids were further utilized to fabricate a non-enzymatic amperometric biosensor for the sensitive detection of hydrogen peroxide (H2O2), and this biosensor displayed high performances to determine H2O2 with a detection limit of 2.0 × 10-6 M and a linear detection range from 2.0 μM to 7.0 mM.
      Citation: Functional Materials Letters
      PubDate: Fri, 06 Feb 2015 01:36:35 GMT
      DOI: 10.1142/S1793604715500447
  • Fabrication and photocatalytic performance of electrospun PVA/silk/TiO2
           nanocomposite textile
    • Authors: Ming-Chung Wu, Shun-Hsiang Chan, Ting-Han Lin
      Abstract: Functional Materials Letters, Ahead of Print. Many organic/inorganic nanocomposites have been fabricated into fibrous materials using electrospinning techniques, because electrospinning processes have many attractive advantages and the ability to produce relatively large-scale continuous films. In this study, the polyvinyl alcohol (PVA)/silk/titanium dioxide (TiO2) nanocomposite self-cleaning textiles were successfully produced using electrospinning technique. After optimizing electrospinning conditions, we successfully obtained the PVA/silk/TiO2 nanocomposite fibers with average diameter of ∼220 nm and TiO2 concentration can be as high as 18.0 wt.%. For the case of the PVA/silk/TiO2 nanocomposite textile, the color of brilliant green coated on the textile surface changed from the initial green color to colorless after ultraviolet (UV) irradiation. Because of its worthy photocatalytic performance, the developed PVA/silk/TiO2 nanocomposite materials in this study will be beneficial for the design and fabrication of multifunctional fibers and textiles.
      Citation: Functional Materials Letters
      PubDate: Thu, 15 Jan 2015 03:39:28 GMT
      DOI: 10.1142/S1793604715400135
  • Influence of Sm3+ doping on microstructure and electrical properties of
    • Authors: Jia-Hu Ouyang, Cheng Zhu, Zhan-Guo Liu, Zhe Ren, Lin Jing
      Abstract: Functional Materials Letters, Ahead of Print. (Nd0.7Yb0.3)2Zr2O7 and ((Nd0.7Yb0.3)1-xSmx)2Zr2O7(0 < x ≤ 0.25) ceramics have been synthesized by pressureless sintering by tailoring the chemical compositions. Microstructure and electrical conductivity of ((Nd0.7Yb0.3)1-xSmx)2Zr2O7 were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and AC impedance spectroscopy. (Nd0.7Yb0.3)2Zr2O7 ceramic exhibits a mixed crystal structure of defect fluorite and pyrochlore. After doping with Sm3+ cations, the structure changes from a mixed type of (Nd0.7Yb0.3)2Zr2O7 to a single pyrochlore type of ((Nd0.7Yb0.3)1-xSmx)2Zr2O7, as the addition of Sm3+ reduces the difference in ionic radius between Nd3+ and Yb3+. However, ((Nd0.7Yb0.3)1-xSmx)2Zr2O7 ceramics contain the localized short-range disorder despite the structural order overall in the pyrochlore. The measured total conductivities of ((Nd0.7Yb0.3)1-xSmx)2Zr2O7 obey the Arrhenius relation. Doping of Sm3+ enhances the electrical conductivity of (Nd0.7Yb0.3)2Zr2O7 ceramic significantly, which is closely related to the variations in the concentration of oxygen vacancies at 48f sites, relatively low activation energy and high pre-exponential factor caused by the long-range order and short-range disorder.
      Citation: Functional Materials Letters
      PubDate: Thu, 15 Jan 2015 03:39:27 GMT
      DOI: 10.1142/S1793604715400123
  • Magnetic and dielectric properties of 3Y-TZP/strontium doped barium
           ferrite composite
    • Authors: Chao Zhang, Shan-Shan Wang, Rui-Song Guo, Guang-Lan Cai, Wei-Na Guo, Chen Wu
      Abstract: Functional Materials Letters, Ahead of Print. Magnetic and dielectric properties of 3Y-TZP/20 wt.% Ba1-xSrxFe12O19(x = 0, 0.25, 0.5, 0.75) composites prepared by solid state reaction method are investigated. The magnetic properties are improved in the composites with the strontium doped barium ferrite. When x = 0.25, the saturation magnetization of the ferrite reaches the maximum. This is due to the migration of Fe3+ induced by the Sr2+ doping. The dielectric properties are also improved in the composite with the strontium doped barium ferrite. When x = 0.5, the dielectric constant and dielectric loss possess the maximum. This is caused by the lattice distortion resulting from the Sr2+ doping. The dielectric properties are analyzed by the universal relaxation law.
      Citation: Functional Materials Letters
      PubDate: Wed, 14 Jan 2015 02:59:28 GMT
      DOI: 10.1142/S179360471550040X
  • Synthesis and physical properties of quasi-one-dimensional magnetic
           material Ca3LiRuO6
    • Authors: Dapeng Wu, Yang Qi
      Abstract: Functional Materials Letters, Ahead of Print. Ca3LiRuO6 single crystals were grown using the flux method, magnetic properties measurement results along different directions of needle-like single crystals are reported for the first time and show Ca3LiRuO6 occurs a paramagnetic (PM)-weak ferromagnetic (FM) transition at a temperature Tc = 120 K, also the magnetic moment aligns in the ab plane. Although Ca3LiRuO6 is characterized by one-dimensional configuration in crystallographic structure, it has three-dimensional (3D) magnetic order, the value of Tc is far below the magnitude of Curie–Weiss temperature. Θcw ≈ -306 K indicates complex nature of the magnetism is in this compound.
      Citation: Functional Materials Letters
      PubDate: Fri, 09 Jan 2015 08:22:45 GMT
      DOI: 10.1142/S1793604715500393
  • Author Index Volume 7 (2014)
    • Abstract: Functional Materials Letters, Volume 07, Issue 06, December 2014.
      Citation: Functional Materials Letters
      PubDate: Wed, 17 Dec 2014 06:43:28 GMT
      DOI: 10.1142/S179360471499001X
  • Energetic and thermal properties of tilt grain boundaries in
           graphene/hexagonal boron nitride heterostructures
    • Authors: Mingchao Wang, Guangping Zhang, Huisheng Peng, Cheng Yan
      Abstract: Functional Materials Letters, Ahead of Print. Graphene/hexagonal boron nitride (G/h-BN) heterostructure has attracted tremendous research efforts owing to its great potential for applications in nanoscale electronic devices. In such hybrid materials, tilt grain boundaries (GBs) between graphene and h-BN grains may have unique physical properties, which have not been well understood. Here we have conducted non-equilibrium molecular dynamics simulations to study the energetic and thermal properties of tilt GBs in G/h-BN heterostructures. The effect of misorientation angles of tilt GBs on both GB energy and interfacial thermal conductance are investigated.
      Citation: Functional Materials Letters
      PubDate: Mon, 29 Dec 2014 06:38:52 GMT
      DOI: 10.1142/S1793604715500381
  • Preparation of bionic lotus leaf surfaces using SiO2 nanoparticle-filled
    • Authors: Jianfang Wang, Siwen Qian, Cheng-an Tao, Fang Wang, Sida Zhang, Chenchao Song
      Abstract: Functional Materials Letters, Ahead of Print. A bionic lotus leaf surface is prepared using a nanoparticle filling method that takes modified SiO2 nanoparticles as the filling and a polymer with low surface energy as the matrix. The effects of the mass ratio of SiO2 nanoparticles to the polymer with low surface energy (β) on the surface microstructure, infiltration, and mechanical properties of the bionic lotus leaf surface are discussed. Results show that it is feasible and easy to form a microstructured coating surface using nanoparticle filling. Nanosilica modified by KH570 has better compatibility (infiltration and dispersity) with polymers. The mass ratio between the nanoparticles and the polymer can significantly affect the microstructure and surface properties. As nanoparticle content and aggregation increase, the surface of the coating gradually develops submicron and nanoscale peaks and holes. The contact angle increases sharply to 155° when β = 1.4, showing super-hydrophobicity. However, excessive nanoparticle content causes mechanical failure of the coating surface. Considering the self-cleaning and anti-fouling properties as well as the mechanical properties of the surface, the bionic lotus leaf surface achieves the best comprehensive performance when β = 1.4.
      Citation: Functional Materials Letters
      PubDate: Mon, 29 Dec 2014 06:38:52 GMT
      DOI: 10.1142/S179360471550037X
  • Non-Debye relaxation and resonance phenomena in dielectric spectra of
           CaCu3Ti4O12 family functional ceramic materials
    • Authors: A. V. Turik, A. S. Bogatin
      Abstract: Functional Materials Letters, Ahead of Print. Experimental data on dielectric spectra of calcium copper titanate, CaCu3Ti4O12 (CCTO) family functional ceramics have been studied and analyzed. It is shown that there are both non-Debye relaxation and resonance regions in their spectra. An occurrence of a retardation of complex permittivity and a relaxation of electric modulus is established. An average relaxation frequency of the electric modulus is considerably (in some cases several orders of magnitude) larger than the retardation frequency of the permittivity. A parallel connection of the capacity and complex conductivity is used to model and interpret experimental data on a negative permittivity in the infralow frequency range. Computer simulation enables us to reveal that the hopping conductivity, characteristic for disordered heterogeneous systems, is to be taken into account to describe adequately experimental data on passing the real part of the capacity (or permittivity) through zero. We have found a critical frequency at which the parallel resonance would take place.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:26:04 GMT
      DOI: 10.1142/S1793604715500356
  • Improving dielectric properties and thermal conductivity of polymer
           composites with CaCu3Ti4O12 and β-SiC hybrid fillers
    • Authors: Xin Ouyang, Peng Cao, Weijun Zhang, Zhaohui Huang, Wei Gao
      Abstract: Functional Materials Letters, Ahead of Print. In this paper, we report a series of homogeneous polymeric composites with enhanced dielectric properties and thermal conductivity. The composites were constituted of polyvinylidene fluorides (PVDFs) matrix and CaCu3Ti4O12 (CCTO) monolithic or CCTO/β-SiC hybrid fillers, and prepared by simple melt blending and hot moulding technique. The influence of different types of fillers and their composition on the dielectric response and thermal conductivity of the obtained composites was studied. Results show that hybrid loading is preferred and a reasonable combination of thermal conductivity (0.80 W ⋅ m-1 ⋅ K-1), dielectric constant (~50) and dielectric loss (~0.07) at 103 Hz was achieved in the PVDF composite containing 40 vol.% CCTO and 10 vol.% β-SiC. The strong dipolar and interfacial polarization derived from the fillers are responsible for the enhancement of the dielectric constant, while the formation of thermally conductive networks/chains by β-SiC whiskers contributes to the improved thermal conductivity.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:26:04 GMT
      DOI: 10.1142/S1793604715400111
  • Selectivity and mixed reactant fuel cells
    • Authors: Ilan Riess
      Abstract: Functional Materials Letters, Ahead of Print. Mixed reactant fuel cells (MR-FCs), are aimed at using a uniform mixture of fuel and oxygen applied to both the anode and the cathode. This allows redesign of fuel cells with a significantly simpler construction, having potentially a higher power density, better fuel utilization and be less expensive. The challenge in realizing MR-FCs is finding selective electrodes that can enhance oxygen reduction at the cathode, fuel oxidation at the anode while inhibiting the chemical reaction between the fuel and oxygen in the gas mixture. This task is in particular challenging in solid oxide fuel cells (SOFCs), as they operate at elevated temperatures, where many reactions are easily activated and selectivity is difficult to achieve. As a result no true MR-FC of the SOFC type were reported while some were found for low temperature fuel cells (FCs). The so-called single-chamber-SOFC are not true MR-FCs as they do not contain two selective electrodes, as required. We shall discuss potential ways to search for and develop selective anodes and cathodes for SOFC type MR-FCs. We first consider material properties which should contribute to that goal. This refers to electronic properties of the bulk, band banding under adsorbed specie, point defects in the bulk and on the surface. We then proceed to show how cell design, in particular electrode structure, can contribute to selectivity. Finally operation conditions are considered and it is shown that they also can contribute to selectivity. The operation condition considered are gas mixture composition, gas mixture residence time in the hot zone, hence gas flow rate, current density and temperature. The topics discussed hold for all FC types but are crucial for the SOFC type because of the difficulty to achieve selectivity at elevated temperatures. It is suggested that a concerted effort taking advantage of all those options should allow development of a true SOFC type MR-FC.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:26:03 GMT
      DOI: 10.1142/S179360471540010X
  • Reliable resistive switching and its tunability in La-doped PbTiO3\TiO2
           composite bilayer
    • Authors: Ying Wang, Shaopeng Lin, Xiaoyue Zhang, Weiming Xiong, Biao Wang, Yue Zheng
      Abstract: Functional Materials Letters, Ahead of Print. Nanoscale La-doped PbTiO3(PLT)\TiO2 (PLTT) composite structures have been fabricated. It shows that the structure presents reliable resistive switching (RS) behavior, and importantly, has great tunability on RS characteristics such as forming/set/reset voltages and resistance ratio by adjusting the PLT layer thickness. Particularly, the set voltage can be tuned at a large range from several volts to dozens of volts. Meanwhile, the set current keeps almost the same, indicating the RS is current dominating. The space-charge-limited current (SCLC) feature indicates that the localized traps are decisive for the RS. Our result sheds light on the prospects of composite structures for designing tunable RS devices.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:26:00 GMT
      DOI: 10.1142/S1793604715500332
  • Effects of hydrothermal temperature on the morphology and
           photoelectrocatalytic performance of TiO2-based nanomaterials
    • Authors: Dong Li, Xiujuan Yu, Xiuwen Cheng
      Abstract: Functional Materials Letters, Ahead of Print. TiO2-based nanomaterials (BNMs) photoelectrode was successfully synthesized via a facile and controllable hydrothermal procedure. The as-prepared TiO2-BNMs photoelectrode was characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The resulting TiO2-BNMs samples assembled by different morphologies were obtained through changing hydrothermal temperature that were: (i) One-dimensional (relative to nanosheets) nanobelts at 140°C, (ii) two-dimensional nanosheets at 160–180°C and (iii) three-dimensional network nanowires at 200–220°C. Structural investigation of the obtained nanomaterials revealed that the content of anatase increased as increasing the apparent dimensionality of the materials. The photoelectrochemical performance of TiO2-BNMs photoelectrode was elucidated by comparative investigation on the electron transport and electron–hole (e-/h+) recombination in TiO2-BNMs sample with typically morphology. The photoelectrochemical performance of the TiO2-BNMs sample was obviously dependent on the morphology. Compared to the nanobelts and the network nanowires structure, the two-dimensional nanosheets displayed the more effective photogenerated electron transfer and reduced electron–hole recombination rate. Moreover, two-dimensional nanosheets had significantly enhanced photoelectrocatalytic efficiency for degradation of methyl orange (MO).
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:25:59 GMT
      DOI: 10.1142/S1793604715500344
  • Enhanced adhesion and conductivity of Cu electrode on AlN substrate for
           thin film thermoelectric device
    • Authors: Shaoxiong Hu, Xin Chen, Yuan Deng, Yao Wang, Hongli Gao, Wei Zhu, Lili Cao, Bingwei Luo, Zhixiang Zhu, Guang Ma, Yu Han
      Abstract: Functional Materials Letters, Ahead of Print. The Cu thin film electrode grown on aluminum nitride (AlN) substrate is widely used in the thin film thermoelectric devices due to its high electrical conductivity. We have developed a new type of buffer layer by co-sputtering Ti and Cu forming Ti–Cu layer. The Ti–Cu layer was sputtered on the Ti buffered AlN substrate so that the adhesion and electrical conductivity properties of the Cu film electrode on AlN substrate could be improved. The interface between the thin films and the substrate were characterized by the scanning electron microscope (SEM). Nanoscratch tests were conducted on a nanomechanical test system to investigate the adhesion between the Cu film electrodes and AlN substrate. Meanwhile, accelerated ageing test under thermal cycling was conducted to evaluate the reliability of the thin film electrode. The results show that the adhesion and the reliability of Cu film electrode on AlN substrate have been greatly improved by employing Ti–Cu/Ti buffer layers.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:25:58 GMT
      DOI: 10.1142/S1793604715500320
  • Synthesis of Ag decorated graphene-hierarchical TiO2 nanocomposite with
           enhanced photocatalytic activity
    • Authors: Li Fu, Yuhong Zheng, Zhuxian Fu, Wen Cai, Jinpin Yu
      Abstract: Functional Materials Letters, Ahead of Print. Reduced graphene oxide (RGO) wrapped TiO2/Ag ternary nanocomposite was synthesized via a wet chemical method. The synthesized nanocomposite was characterized using UV-Vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD). The average size of RGO wrapped TiO2 and deposited Ag nanoparticles were 3.2 μm and 48 nm, respectively. Due to the highly facilitated electron transport by the synergistic effect between RGO sheets and Ag nanoparticles, the TiO2/RGO/Ag nanocomposite exhibited a significant enhancement of photocatalytic activity towards degradation of methylene blue under UV light.
      Citation: Functional Materials Letters
      PubDate: Tue, 23 Dec 2014 09:25:58 GMT
      DOI: 10.1142/S1793604715500368
  • Preparation of lignite-based activated carbon with high specific
           capacitance for electrochemical capacitors
    • Authors: Baolin Xing, Jianliang Cao, Yan Wang, Guiyun Yi, Chuanxiang Zhang, Lunjian Chen, Guangxu Huang, Bing Xu
      Abstract: Functional Materials Letters, Ahead of Print. A lignite-based activated carbon (LAC) for electrochemical capacitors (ECs) was prepared from high moisture lignite by KOH activation, and the as-prepared sample was characterized by the N2-sorption, scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical performances of ECs with activated carbon as electrodes in 3 M KOH aqueous solution were evaluated by constant current charge-discharge and cyclic voltammetry. The LAC exhibits a well-developed surface area of 2581 m2/g, a relative wide pore size distribution of 0.5–10 nm. The ECs with LAC as electrode materials presents a high specific capacitance of 392 F/g at a low current density of 50 mA/g, and still remains 315 F/g even at a high current density of 5 A/g. The residual specific capacitance is as high as 92.9% after 2000 cycles. Compared with the commercial activated carbon (Maxsorb: Commercial product, Kansai, Japan), the LAC based electrode materials shows superior capacitive performance in terms of specific capacitance and charge–discharge performance at the high current density.
      Citation: Functional Materials Letters
      PubDate: Tue, 02 Dec 2014 01:33:09 GMT
      DOI: 10.1142/S1793604715500319
  • Structural and optical properties of KNN nanocubes synthesized by a green
           route using gelatin
    • Authors: Gh. H. Khorrami, A. Kompany, A. Khorsand Zak
      Abstract: Functional Materials Letters, Ahead of Print. Sodium potassium niobate nanoparticles [(K0.5Na0.5)NbO3, KNN], KNN-NPs, were synthesized using a modified sol–gel method. Structural and optical properties of the prepared samples were investigated by thermogravometric analyzer (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV–Vis spectroscopy. The XRD patterns showed that the formation of the orthorhombic KNN-NPs starts at 500°C calcination temperature. Raman spectroscopy was used to investigate the crystalline symmetry and the structural deformation of the prepared KNN-NPs. TEM images showed that the morphology of the prepared particles is cubic, with the average size of about 50 nm. From diffused reflectance spectroscopy along with using Kubelka–Munk method, the energy bandgaps were determined to be indirect with the values of 3.13 eV and 3.19 eV for the samples calcined at 500°C and 600°C, respectively.
      Citation: Functional Materials Letters
      PubDate: Tue, 02 Dec 2014 01:33:08 GMT
      DOI: 10.1142/S1793604715500307
  • An non-centrosymmetric mononuclear Zr complex exhibiting UV
    • Authors: Cai-Yun Han, Mei Qu, Qin-Qin Dang, Xian-Ming Zhang
      Abstract: Functional Materials Letters, Ahead of Print. A novel non-centrosymmetric (NCS) orthorhombic complex Zr(dmpu)2Cl4 (1) has been solvothermally prepared in situ from starting materials of Zirconium(IV) acetylacetonate (Zr(acac)4) and N,N-dimethylpropyleneurea (dmpu), in which dmpu can act not only as solvent but also as organic ligand of monodentate oxygen donor. The second-harmonic generation (SHG) measurements reveal that complex 1 has a strong response of 1.4 times that of potassium dihydrogen phosphate (KDP) at 532 nm based on the Kurtz–Perry method. Furthermore, optical transmission study indicates that complex 1 has a wide transparency range in the UV region (200–850 nm) with a cutoff at 291 nm. According to first-principles calculations, the enhanced macroscopic SHG response of 1 can be attributed to the organic ligand dmpu. Therefore, 1 could be a promising candidate for non-linear optical material.
      Citation: Functional Materials Letters
      PubDate: Tue, 02 Dec 2014 01:33:08 GMT
      DOI: 10.1142/S1793604715500290
  • Effect of Sn on sensing performance of nanostructred ZnO film
    • Authors: Yongqin Chang, Changjing Shao, Nan Jiang, Shiqi Wang, Bo Zou, Yi Long
      Abstract: Functional Materials Letters, Ahead of Print. Nanostructured ZnO films were fabricated by chemical vapor deposition (CVD) method with different Sn source concentrations for ethanol and acetone sensing applications. The samples prepared with Sn:ZnO (weight ratio) of 0.1:1, 0.2:1 and 0.3:1 are named as S1, S2 and S3, respectively. It was found that hexagonal wurtzite structure of ZnO is maintained after Sn doping. The S1 sample shows the highest response to acetone, while the S2 sample shows the highest response to ethanol, which confines that the as-grown ZnO films with different Sn source concentrations exhibit obvious selectivity to ethanol and acetone. Working temperature can also be reduced by the increase of Sn source concentration. All the samples have very short average recovery time. Our work provides a prospective approach to obtain high performance gas sensor for ethanol and acetone.
      Citation: Functional Materials Letters
      PubDate: Tue, 02 Dec 2014 01:33:08 GMT
      DOI: 10.1142/S1793604715400093
  • Piezoelectric properties of rhombohedral ferroelectric materials with
           phase transition
    • Authors: Xiaofang Zhao, A. K. Soh
      Abstract: Functional Materials Letters, Ahead of Print. The temporal evolution of domain structure and its piezoelectric behavior of ferroelectric material BaTiO3 during the transition process from rhombohedral to tetragonal phase under an applied electric field have been studied by employing Landau–Ginzburg theory and the phase-field method. The results obtained show that, during the transformation process, the intermediate phase was monoclinic MA phase, and several peak values of piezoelectric coefficient appeared at the stage where obvious change of domain pattern occurred. In addition, by comparing the cases of applied electric field with different frequencies, it was found that the maximum piezoelectric coefficient obtained decreased with increasing frequency value. These results are of great significance in tuning the properties of engineering domains in ferroelectrics, and could provide more fundamentals to the design of ferroelectric devices.
      Citation: Functional Materials Letters
      PubDate: Wed, 19 Nov 2014 02:00:58 GMT
      DOI: 10.1142/S1793604715400081
  • Effects of flow rate of atmosphere gases on the characteristics of
           Zn-doped ITO (ZITO) thin films for organic light emitting diodes
    • Authors: Hwa-Kyun Jeong, Kyu-Mann Lee
      Abstract: Functional Materials Letters, Ahead of Print. We have investigated the effect of ambient gases on the structural, electrical, and optical characteristics of Zn-doped indium tin oxide (ZITO) thin films intended for use as anode contacts in organic light emitting diodes (OLED) devices. These ZITO thin films are deposited by radio frequency (RF) magnetron sputtering under different ambient gases (Ar, Ar + O2 and Ar + H2) at 300°C. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.1 sccm to 0.5 sccm and from 0.1 sccm to 1 sccm, respectively. The intensity of the (400) peak in the ZITO thin films increases with increasing H2 flow rate whilst the (400) peak was nearly invisible in an atmosphere of Ar + O2. The electrical resistivity of the ZITO thin films increases with increasing O2 flow rate, whereas the electrical resistivity decreases with increasing H2 flow rate. The change of electrical resistivity with changes in the ambient gas composition is mainly interpreted in terms of the charge carrier mobility and the charge carrier concentration. All the films show an average transmittance of over 80% in the visible range. The optical bandgap of the ZITO films increases with increasing H2 flow rates, whereas the optical bandgap of the ZITO films deposited in an O2 atmosphere decreases with increasing O2 flow rates. The current density and the luminance of the OLED devices with ZITO thin films deposited in 1 sccm of H2 ambient gas are the highest among all the films. The optical bandgap energy of ZITO thin films plays a major role in OLED device performance, especially the current density and luminance.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:01 GMT
      DOI: 10.1142/S179360471540007X
  • Electrochemical oxidation of glucose on gold nanoparticle-modified reduced
           graphene oxide electrodes in alkaline solutions
    • Authors: Qiaofang Shi, Guowang Diao, Shaolin Mu
      Abstract: Functional Materials Letters, Ahead of Print. A given amount of gold is electrodeposited on the reduced graphene oxide (RGO)/glassy carbon (GC) electrodes to form Au/RGO/GC electrodes, which are carried out at different potentials. The Au/RGO/GC electrode with Au loading of 250 μg cm-2 prepared at a constant potential of -0.30 V exhibits the best electrocatalytic activity to glucose oxidation in alkaline solutions because of homogeneous dispersion of gold nanoparticles with smaller sizes. This electrode shows long-term stability, rapid charge transfer ability, and higher current density compared to other gold electrodes reported previously.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:01 GMT
      DOI: 10.1142/S1793604715400044
  • Efficient reduction of graphene oxide nanosheets using Na2C2O4 as a
           reducing agent
    • Authors: Mohamad Fahrul Radzi Hanifah, Juhana Jaafar, Madzlan Aziz, A. F. Ismail, M. H. D. Othman, Mukhlis A. Rahman, M. N. A. M. Norddin, N. Yusof, W. N. W. Salleh
      Abstract: Functional Materials Letters, Ahead of Print. The efficient synthesis of reduced graphene oxide (RGO) nanosheets via chemical reduction process of exfoliated graphene oxide (GO) nanosheets was performed by introducing sodium oxalate (Na2C2O4) as a reducing agent. To study the effects of the reduction time on the synthesized RGO, the GO was reduced within -1/2, 1 and 2 h for RGO-1, RGO-2 and RGO-3, respectively. The C/O atomic ratio of the synthesized RGO-3 has increased from 2.16 to 6.32 after reduction as determined by X-ray photoelectron spectroscopy (XPS). The morphology analysis of the RGO-3 was determined by high-resolution transmission electron microscopy (HRTEM) almost revealed the formation of single layer. The number of RGO layers decreases as the time of the reduction increases. Based on these analysis results, sodium oxalate plays an important role in the efficient removal of the oxygen containing groups in the GO to produce high quality of RGO.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:01 GMT
      DOI: 10.1142/S1793604715500265
  • The magnetism of BiFeO3 powders
    • Authors: Xi Luo, Li-Ting Tseng, Sean Li, Jiabao Yi
      Abstract: Functional Materials Letters, Ahead of Print. Conventional sintering and direct ball milling of Bi2O3 + Fe2O3 mixture were used for the fabrication of BiFeO3 powders. The fabricated powders were performed annealing or high energy ball milling to vary the grain size from bottom-up or top-down. It was found that the magnetization of the powders synthesized by both methods plotted with the reciprocal of the grain size could be linearly fitted, indicating that the magnetism is from the finite size effect. Exchange bias phenomenon was observed after field cooling (FC) of the powders, confirming the magnetization is due to the uncompensated or canted surface spins. No spin glass behavior was found in these powders.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:00 GMT
      DOI: 10.1142/S1793604715500277
  • Metal molybdate nanorods as non-precious electrocatalysts for the oxygen
    • Authors: Tian Wu, Lieyu Zhang
      Abstract: Functional Materials Letters, Ahead of Print. Development of non-precious electrocatalysts with applicable electrocatalytic activity towards the oxygen reduction reaction (ORR) is important to fulfill broad-based and large-scale applications of metal/air batteries and fuel cells. Herein, nickel and cobalt molybdates with uniform nanorod morphology are synthesized using a facile one-pot hydrothermal method. The ORR activity of the prepared metal molybdate nanorods in alkaline media are investigated by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperomety in rotating disk electrode (RDE) techniques. The present study suggests that the prepared metal molybdate nanorods exhibit applicable electrocatalytic activities towards the ORR in alkaline media, promising the applications as non-precious cathode in fuel cells and metal–air batteries.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:00 GMT
      DOI: 10.1142/S1793604715400056
  • Enhancement effects of two kinds of carbon black on piezoelectricity of
           PVDF-HFP composite films
    • Authors: Bin Hu, Ning Hu, Liangke Wu, Hao Cui, Ji Ying
      Abstract: Functional Materials Letters, Ahead of Print. Two kinds of carbon black (CB) (i.e., CB#300 and CB#3350) were added into poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), respectively, to improve its piezoelectricity. The results revealed that when 0.5 wt.% CB was added, the best performance of the PVDF-HFP/CB composite films was obtained. The calibrated open circuit voltage and the density of harvested power of 0.5 wt.% CB#3350 contained composite films were 204%, and 464% (AC) and 561% (DC) of those of neat PVDF-HFP films. Similarly, for 0.5 wt.% CB#300 contained films, they were 211%, and 475% (AC) and 624% (DC), respectively. The enhancement mechanisms of piezoelectricity were clarified by the observation of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and scanning electron microscope (SEM). We found that the added CBs act as nucleate agents to promote the formation of elongated, oriented and fibrillar β-phase crystals during the fabrication process, which increase the piezoelectricity. Overdosed CBs lead to a lower crystallinity degree, resulting in the lower piezoelectricity. Compared with CB#3350, CB#300 performs slightly better, which may be ascribed to its higher specific surface area.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:00 GMT
      DOI: 10.1142/S1793604715400068
  • Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency
    • Authors: Qilong Guo, Sijun Luo
      Abstract: Functional Materials Letters, Ahead of Print. We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of ~0.8 at 700 K which is a ~60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb-based material have been discussed.
      Citation: Functional Materials Letters
      PubDate: Tue, 18 Nov 2014 01:48:00 GMT
      DOI: 10.1142/S1793604715500289
  • Synthesis of spinel LiMn2O4 cathode material by a modified solid state
    • Authors: Jiawei Zhang, Shudong Lin, Keyan Li, Fenfen Shua, Kunfeng Chen, Liqiu Wang, Dongfeng Xue
      Abstract: Functional Materials Letters, Ahead of Print. Spinel LiMn2O4 was synthesized by a modified solid state reaction. We pretreated the reactants using tartaric acid as complexing agent through a grinding process to obtain uniform distribution of metal ions at atomic level. The structures, morphologies and electrochemical properties of the products were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and galvanostatic charge-discharge test. The results show that adding tartaric acid during the chemical pretreatment plays an important role in the formation of regular and uniform particles, which is beneficial to the electrochemical performance of LiMn2O4. At the current density of 100 mA g-1, the discharge capacity is 118 mAh g-1 after 50 cycles with the capacity retention of 97%.
      Citation: Functional Materials Letters
      PubDate: Mon, 10 Nov 2014 06:38:47 GMT
      DOI: 10.1142/S1793604715400020
  • Enhanced piezoelectricity and photoluminescence in Dy-doped
           Ba0.85Ca0.15Ti0.9Zr0.1O3 lead-free multifunctional ceramics
    • Authors: Fengying Lei, Na Jiang, Lingling Luo, Yongquan Guo, Qiaoji Zheng, Dunmin Lin
      Abstract: Functional Materials Letters, Ahead of Print. Lead-free multifunctional ceramics of Ba0.85Ca0.15Ti0.9Zr0.1O3-x mol% Dy have been prepared by an ordinary sintering method and the effects of Dy2O3 doping on structure, piezoelectric, ferroelectric and photoluminescent properties of the ceramics have been studied. The ceramics possess a single phase perovskite structure. The grain growth of the ceramics is prohibited and the ferroelectric–paraelectric phase transition at TC becomes more diffusive after the addition of Dy2O3. Dy2O3 doping improves the piezoelectricity of the ceramics and the optimal piezoelectric properties d33 = 335 pC/N is obtained at x = 0.5. The addition of 2 mol% Dy enhances the photoluminescent properties of the ceramics and strong emissions at ~ 478 nm and ~ 575 nm are observed. Our study shows that the ceramics with low Dy2O3 levels exhibit simultaneously the strong piezoelectricity, ferroelectricity and photoluminescence and may have a potential application in mechano-electro-optic integration and coupling device.
      Citation: Functional Materials Letters
      PubDate: Mon, 10 Nov 2014 06:38:46 GMT
      DOI: 10.1142/S1793604715400019
  • Material and physical model for evaluation of deep brain activity
           contribution to EEG recordings
    • Authors: Yan Ye, Xiaoping Li, Tiecheng Wu, Zhe Li, Wenwen Xie
      Abstract: Functional Materials Letters, Ahead of Print. Deep brain activity is conventionally recorded with surgical implantation of electrodes. During the neurosurgery, brain tissue damage and the consequent side effects to patients are inevitably incurred. In order to eliminate undesired risks, we propose that deep brain activity should be measured using the noninvasive scalp electroencephalography (EEG) technique. However, the deeper the neuronal activity is located, the noisier the corresponding scalp EEG signals are. Thus, the present study aims to evaluate whether deep brain activity could be observed from EEG recordings. In the experiment, a three-layer cylindrical head model was constructed to mimic a human head. A single dipole source (sine wave, 10 Hz, altering amplitudes) was embedded inside the model to simulate neuronal activity. When the dipole source was activated, surface potential was measured via electrodes attached on the top surface of the model and raw data were recorded for signal analysis. Results show that the dipole source activity positioned at 66 mm depth in the model, equivalent to the depth of deep brain structures, is clearly observed from surface potential recordings. Therefore, it is highly possible that deep brain activity could be observed from EEG recordings and deep brain activity could be measured using the noninvasive scalp EEG technique.
      Citation: Functional Materials Letters
      PubDate: Mon, 10 Nov 2014 06:38:46 GMT
      DOI: 10.1142/S1793604715400032
  • Strontium-substituted Ba(Ce,Zr)O3−δ oxides for proton
           conducting membranes
    • Authors: Wojciech Zając, Emil Hanc
      Abstract: Functional Materials Letters, Ahead of Print. This paper is focused on Ba1-xSrx(Ce0.75Zr0.25)0.9Nd0.1O2.95 proton-conducting oxides, for which the effect of substitution of barium by strontium in a full range of compositions is studied. Crystal lattice symmetry, proton conductivity and stability in CO2 atmosphere are discussed. Substitution of barium by strontium reduces toxicity and does not deteriorate chemical stability, however, crystal lattice of the strontium-substituted perovskites is more distorted, causing reduction of proton conductivity more than one order of magnitude. Balance between opposite tendencies can be found at low Sr content, e.g., 25 at.%.
      Citation: Functional Materials Letters
      PubDate: Fri, 07 Nov 2014 03:54:07 GMT
      DOI: 10.1142/S1793604714400141
  • Red-emitting AlN:Mn2+ phosphors prepared by combustion synthesis
    • Authors: Zhongqi Shi, Yongyong Zou, Ruifeng Jing, Kuo Zhang, Guanjun Qiao, Hongjie Wang
      Abstract: Functional Materials Letters, Ahead of Print. Red-emitting Mn2+-doped AlN (AlN:Mn2+) phosphors were successfully prepared by a highly effective combustion synthesis method. The phase purity, morphology, element-composition and luminescence properties of the synthesized phosphors were investigated. X-ray diffraction (XRD) results show that the Mn2+-doped into the AlN host did not induce a second phase and distort the structure significantly. Scanning electron microscopy (SEM) images display that the phosphors have an irregular shape with a particle size in the range of 1–5 μm. X-ray photoelectron spectroscopy (XPS) spectrum indicates that Mn ions are divalent state. The synthesized AlN:Mn2+ phosphors exhibit a strong red emission centered at ~ 600 nm, which is ascribe to the 4T1(4G)–6A1(6S) transition of Mn2+ under ultraviolet excitation. The emission intensity reaches its maximum when Mn2+-doped concentration is 3 mol%.
      Citation: Functional Materials Letters
      PubDate: Fri, 07 Nov 2014 03:54:05 GMT
      DOI: 10.1142/S1793604715500253
  • Adsorptive performance for methylene blue of magnetic Ni@activated carbon
    • Authors: Panfeng Wang et al
      Abstract: Functional Materials Letters, Ahead of Print. Owing to the unique microporous structure and high specific surface area, activated carbon (AC) can act as a good candidate for functional materials. In this paper, Ni@AC magnetic nanocomposites with excellent magnetic response are synthesized by the hydrothermal method. All Ni@AC nanocomposites present ferromagnetism and Ni nanoparticles exist in the pores of AC. The saturation magnetization (Ms) increases with the increasing content of Ni, while the specific surface area and pore volume decrease. The S-50 sample possesses the parameters of the specific surface area of 1156.8 m2 ⋅ g-1 and Ms of 3.5 emu/g. Furthermore, the methylene blue (MB) removal analysis indicates that 99% MB can be adsorbed in 50 min. The as-prepared Ni@AC nanocomposites present good adsorptive capacity of MB and can be separated easily from water by magnetic separation technique.
      PubDate: Thu, 30 Oct 2014 03:41:01 GMT
      DOI: 10.1142/S1793604715500241
  • Comparison of photovoltaic performance of TiO2 nanoparticles based thin
           films via different routes
    • Authors: Yajun Ji
      Abstract: Functional Materials Letters, Ahead of Print. Well crystallized TiO2 nanoparticles were prepared by hydrothermal and sol–gel routes, respectively. The morphologies, structures, crystallinity and optical properties of resulted TiO2 nanoparticles-based thin films via the two methods were examined by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and reflectance spectra. In addition, comparison of photovoltaic performance of TiO2 nanoparticles-based thin films by the two methods was performed. It is found that the maximum energy conversion efficiency of 4.06% was achieved based on the obtained electrode via hydrothermal, which is much better than that of the sol–gels route. The uniform film structure with improved dye absorption capability, increased diffused reflectance property and relatively low charge recombination rates for injected electrons are believed to be responsible to the superior photoelectrochemical properties of dye-sensitized solar cells (DSSC) via hydrothermal route.
      PubDate: Fri, 24 Oct 2014 09:28:48 GMT
      DOI: 10.1142/S179360471550023X
  • Luminescence properties and first principles calculations of Dy3+
           activated Sr3B2O6 phosphors
    • Authors: Lihan Cai et al
      Abstract: Functional Materials Letters, Ahead of Print. A novel white-light-emitting Sr3B2O6:Dy3+ phosphor was prepared by solid-state reactions and its luminescence properties were investigated. The excitation spectrum of obtained phosphor monitored at 479 nm covers a very broad spectral region from 320 nm to 460 nm with peaks at 323, 349, 363, 386, 427 and 456 nm. Under excitation at 349 nm, the phosphor exhibits a blue emission centered at 479 nm and a yellow emission centered at 574 nm. The optimal doping concentration of Dy3+ is obtained to be 7 mol%, and the concentration quenching is observed when the concentration of Dy3+ exceeds 7 mol%. This concentration quenching is due to the enhanced energy exchange among Dy3+ ions. The CIE chromaticity coordinate (0.289, 0.302) of Sr3-0.07B2O6:0.07 Dy3+ located in the white-light region can be achieved. Theoretical calculations of electronic properties for Sr3B2O6:Dy3+ phosphor in the framework of the density functional theory (DFT) were carried out. Our results suggest that the Sr3B2O6:Dy3+ phosphor is a promising single-component white-light-emitting material.
      PubDate: Tue, 21 Oct 2014 03:47:38 GMT
      DOI: 10.1142/S1793604715500228
  • Preparation of nanoporous graphene and the application of its
           nanocomposite membrane in propylene/propane separation
    • Authors: Hai-Xiang Sun et al
      Abstract: Functional Materials Letters, Ahead of Print. Chemically reduced graphene oxide containing hydroxyl groups and a wide size distribution of nanopores was prepared by a facile one-pot hydrothermal method. The resulting material was characterized by transmission electron microscopy (TEM), Raman spectroscopy, surface area measurement and attenuated total reflection infrared spectroscopy (ATR-FTIR), respectively. It was found that this reduced graphene oxide exhibited more clear nanopores and hydroxyl groups in the basal plane. Then the morphologies of the nanocomposite membrane incorporated into the nanoporous graphene were investigated through scanning electron microscopy (SEM), and the permeation test also was performed. Notably, the results showed that the nanocomposite membrane had a homogenous morphology and a better performance (separation factor 11.09) than polymer membrane in the separation of propylene/propane. This work demonstrates that nanoporous graphene exhibits great potential in the field of olefin/paraffin separation.
      PubDate: Tue, 21 Oct 2014 03:47:38 GMT
      DOI: 10.1142/S1793604715500198
  • Transport properties of Bi2Se3 thin films grown by magnetron sputtering
    • Authors: Z. T. Wei et al
      Abstract: Functional Materials Letters, Ahead of Print. Epitaxial growth of Bi2Se3 thin films is of great current interest due to the advantages in spintronics and thermoelectrical applications. In this paper, Bi2Se3 thin films on Si (111) substrate have been prepared via magnetron sputtering deposition with post-annealing treatment and their microstructures and electrical transport properties were studied. Good quality with highly c-axis oriented films could be obtained after post-annealing treatment. The annealing temperature (Ta) obviously affected the phase structures and electrical properties. The crystallinity and the lattice parameters c of the Bi2Se3 thin-films increased with increasing Ta. The relative atomic ratio of Se/Bi decreased with increasing Ta and large number of Se vacancies was discovered in films with Ta = 350°C. The resistivity of films decreased monotonously and showed weakly metallic resistivity with the increase of Ta. Non-saturated high-field linear magnetoresistance and weak antilocalization were found in films with higher Ta.
      PubDate: Tue, 21 Oct 2014 03:47:38 GMT
      DOI: 10.1142/S1793604715500204
  • Graphene modified Li-rich cathode material Li[Li0.26Ni0.07Co0.07Mn0.56]O2
           for lithium ion battery
    • Authors: Xiangjun Li et al
      Abstract: Functional Materials Letters, Ahead of Print. Lithium and Mn rich solid solution materials Li[Li0.26Ni0.07Co0.07Mn0.56]O2 were synthesized by a carbonate co-precipitation method and modified with a layer of graphene. The graphene-modified cathodes exhibit improved rate capability and cycling performance as compared to the bare cathodes. Electrochemical impedance spectroscopy (EIS) analyses reveal that the improved electrochemical performances are due to acceleration kinetics of lithium-ion diffusion and the charge transfer reaction of the graphene-modified cathodes.
      PubDate: Tue, 21 Oct 2014 03:47:37 GMT
      DOI: 10.1142/S179360471440013X
  • Electrochemical studies on nanometal oxide-activated carbon composite
           electrodes for aqueous supercapacitors
    • Authors: Mui Yen Ho et al
      Abstract: Functional Materials Letters, Ahead of Print. In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge–discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+Na+ and can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode–electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.
      PubDate: Tue, 21 Oct 2014 03:47:37 GMT
      DOI: 10.1142/S1793604714400128
  • Uniform Bi2O2CO3 hierarchical nanoflowers: solvothermal synthesis and
           photocatalytic properties
    • Authors: Feng Cao et al
      Abstract: Functional Materials Letters, Ahead of Print. Well-defined flowerlike Bi2O2CO3 nanostructures were fabricated by a simple one-pot solvothermal method with high yield. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy, nitrogen sorption, photoluminescence spectra and UV–visible diffuse reflectance spectroscopy. The photocatalytic properties of the as-prepared samples were further investigated by photocatalytic decomposition of Rhodamine B (RhB) dye, and it was found that the Bi2O2CO3 nanoflowers showed a good photocatalytic activity under UV light. The excellent photocatalytic performance of Bi2O2CO3 flowerlike nanostructures is related to its special nanostructure and morphology, indicates its potential application in photocatalysis and nanosensors.
      PubDate: Tue, 21 Oct 2014 03:47:36 GMT
      DOI: 10.1142/S1793604715500216
  • Wollastonite hybridizing stearic acid as thermal energy storage material
    • Authors: Dawei Xu et al
      Abstract: Functional Materials Letters, Ahead of Print. This paper reported on the preparation of a novel stearic acid (SA)/wollastonite (W) composite as a form-stable phase change material (PCM) for thermal energy-storage (TES) by vacuum impregnation, and especially investigated the effect of the size grade of W on the thermal properties of the SA/W composite. Samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle-size analysis, and differential scanning calorimetry (DSC). Natural W (Wr) was classified into four size grades by wet screening. The results indicate that no chemical reaction took place between SA and W, and the SA load in the SA/W composite increased with an increase in the length/diameter (L/D) ratio of the W. The SA/W composite with a W L/D ratio of 22.5 exhibited latent heats of melting and freezing of 58.64 J/g and 56.95 J/g, respectively, which was higher than those of the composite incorporating natural W. We believe that the as-prepared form-stable PCM composite could provide a potential means of TES for the concentrated solar power.
      PubDate: Tue, 14 Oct 2014 02:22:03 GMT
      DOI: 10.1142/S1793604714400116
  • Synthesis and photocatalytic property of porous metal oxides nanowires
           based on carbon nanofiber template
    • Authors: Weiqiang Fan et al
      Abstract: Functional Materials Letters, Ahead of Print. A series of porous metal oxides nanowires (Fe2O3, Co3O4, NiO and CuO) have been successfully synthesized, where commercial carbon nanofibers were used as the template. The obtained samples were systematically characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis diffuse reflectance (UV–Vis DR) spectra and transmission electron microscope (TEM). According to the photodegradation data, the porous metal oxides nanowires exhibit significantly photocatalytic activity for degrading tetracycline (TC). Furthermore, the porous Fe2O3 nanowires show the best photocatalytic performance among all the samples.
      PubDate: Fri, 10 Oct 2014 05:49:44 GMT
      DOI: 10.1142/S1793604715500186
  • Low-cost, flexible graphene/polyaniline nanocomposite paper as binder-free
           high-performance supercapacitor electrode
    • Authors: Li Wang et al
      Abstract: Functional Materials Letters, Ahead of Print. Nanopolyaniline coated graphene (GNP) was synthesized and flexible composite paper based on as-prepared GNP composite was fabricated by rolling process. Uniform PANI nanocoating prevents the graphene sheets from re-stacking during paper fabrication under high pressure. The composite paper was directly used as the supercapacitor without adding any binder and a specific capacitance of 255 F g-1 was achieved with high rate retention.
      PubDate: Fri, 10 Oct 2014 05:49:44 GMT
      DOI: 10.1142/S1793604714400104
  • Electrical properties modulation of thin film solar cell using gold
           nanostructures at textured FTO/p–i–n interface
    • Authors: A. Gentile et al
      Abstract: Functional Materials Letters, Ahead of Print. We report about the modulation of the electrical properties of thin film solar cells due to the incorporation of size-selected Au nanostructures (NSs) at a textured FTO/p–i–n interface. By increasing the Au NSs size, the analyses of current-voltage characteristics show lower Schottky barrier heights and the gradual reduction of the open-circuit voltages (VOC). The optical measurements show higher parasitic absorption by larger Au NSs that reduces the amount of radiation transmitted by the transparent to absorber layer. This process decreases the number of photo-generated carriers and may explain the VOC reduction related to the devices with larger Au NSs at the interface. So, the correlation between materials properties and device performances was established.
      PubDate: Wed, 01 Oct 2014 10:07:01 GMT
      DOI: 10.1142/S1793604715500174
  • Fabrication of ordered mesoporous carbon film supporting vanadium oxides
           for electrochemical supercapacitor
    • Authors: Chunxia Zhao et al
      Abstract: Functional Materials Letters, Ahead of Print. Ordered mesoporous carbon film supporting vanadium oxide nanoparticles has been synthesized via ultrasound-assistant impregnation method with ordered mesoporous carbon C-FDU15 film as the host and V2O5 sol as the guest precursor. The hybrids exhibit type IV sorption isotherms with H2 hysteresis loop, indicating the well-retained characteristics of ordered mesoporous structure. The capacitance of the materials is enhanced with V2O5 loading. Particularly, the hybrids with 32.26 wt.% V2O5 loading yield an important capacitance of 128 F/g in 1 mol/L KNO3 electrolyte under a potential range from -0.6 V to 0.6 V. The improved specific capacitance of the hybrids is proposed to be the combination of the double-layer capacitance of ordered porous structure and the pseudocapacitance derived from V2O5.
      PubDate: Wed, 01 Oct 2014 10:06:48 GMT
      DOI: 10.1142/S1793604715500162
  • Nanoporous WO3–Fe2O3 films; structural and photo-electrochemical
    • Authors: Renata Solarska et al
      Abstract: Functional Materials Letters, Ahead of Print. We investigated the structure and photo-electrochemical properties for water splitting of tungsten trioxide-ferric oxide thin films formed by spray pyrolysis. While annealing at 600°C produces films consisting of a mixture of monoclinic WO3 and hematite α-Fe2O3, the heating at a temperature above 1000°C affords formation of ferric tungstate Fe2WO6. Both kinds of films exhibit optical absorption range comparable or exceeding that of α-Fe2O3. Another important feature is a decreased rate of charge recombination of the mixed-oxide Fe2O3-WO3 with respect to the ferric oxide photo-anodes.
      PubDate: Wed, 24 Sep 2014 08:11:23 GMT
      DOI: 10.1142/S1793604714400062
  • Blue shift in the optical bandgap of tin oxide thin films by controlling
           oxygen-to-argon gas flow ratio
    • Authors: Meenakshi et al
      Abstract: Functional Materials Letters, Ahead of Print. Tin oxide (SnO2) thin films were deposited by radio-frequency (RF) magnetron sputtering on silicon and glass substrates at different oxygen-to-argon gas-flow ratio (O2-to-Ar = 0%, 10%, 20%, 30% and 50%). All films were deposited at room temperature and fixed working pressures, 10 mTorr. X-ray diffraction (XRD) measurement suggests that all films were crystalline in nature except film deposited only in argon environment. The transparency of all of the films was more than 85% in the visible range except the film deposited only in the argon environment. Atomic force microscopy results showed that the surface of all the films were highly flat and smooth. The optical bandgap, estimated by Tauc plot was increased with oxygen environment. Blue shift was observed in the absorption edge and was accounted to decrease in the oxygen vacancies and dangling bonds.
      PubDate: Tue, 16 Sep 2014 08:45:02 GMT
      DOI: 10.1142/S1793604715500149
  • Electric and thermoelectric properties of CdTe/PbTe epitaxial
    • Authors: Michal Szot et al
      Abstract: Functional Materials Letters, Ahead of Print. The electric and thermoelectric properties of novel, CdTe/PbTe layered nanocomposite material are investigated. The molecular beam epitaxy (MBE) method was used for preparation of samples with well controlled distances (from 20 to 70 nm) between the layers of CdTe nanograins embedded in PbTe thermoelectric matrix as well as with number of these layers from 2 to 10. The Hall effect measurements performed in temperature range from 4–300 K revealed that carrier mobility is strongly affected by scattering on CdTe grain boundaries. The observation of Shubnikov-de Haas oscillations confirms high quality of the samples and allows determination of effective mass of conducting electrons m* = 0.04m0. The measurements of the room temperature Seebeck coefficient together with electrical conductivity lead to the power factors which are comparable to those reported in PbTe/CdTe polycrystalline solid solutions.
      PubDate: Tue, 16 Sep 2014 08:45:02 GMT
      DOI: 10.1142/S1793604714400074
  • Facile synthesis of CuO nanoparticles as anode for lithium ion batteries
           with enhanced performance
    • Authors: Linlin Wang et al
      Abstract: Functional Materials Letters, Ahead of Print. Particle size effects on the electrochemical performance of the CuO particles toward lithium are essential. In this work, a low-cost, large-scale production but simple approach has been developed to fabricate CuO nanopaticles with an average size in ~130 nm through thermolysis of Cu(OH)2 precursors. As anode materials for lithium ion batteries (LIBs), the CuO nanoparticles deliver a high reversible capacity of 540 mAh g-1 over 100 cycles at 0.5 C. It also exhibits a rate capacity of 405 mAh g-1 at 2 C. These results suggest that the facile synthetic method of producing the CuO nanoparticles can enhance cycle performance, superior to that of some different sizes of the CuO nanoparticles and many reported CuO-based anodes.
      PubDate: Tue, 16 Sep 2014 08:45:02 GMT
      DOI: 10.1142/S1793604714400086
  • Origin of the high tunability of BaTiSnO3 thin films deposited by
    • Authors: Manuel Mascot et al
      Abstract: Functional Materials Letters, Ahead of Print. Ba(Sn0.02Ti0.98)O3 thin films (BTS) were prepared by sol–gel route and deposited by spin-coating on commercial Pt/Ti/SiO2/Si substrates. By modifying the annealing conditions from 750°C at 1 h to 950°C at 15 min, the relative tunability nr at 100°C in the paraelectric state increased from 45 to 70% while the DC dielectric permittivity ε′(0) increased as well. The evolutions of ε′(E) and nr(E) are explained from Devonshire thermodynamic formalism. The very high value of tunability of 70% is explained by the grain size increase of our BTS thin films and the decrease of the dead layer effect when the annealing conditions are optimized.
      PubDate: Tue, 16 Sep 2014 08:45:02 GMT
      DOI: 10.1142/S1793604715500150
  • Electronic origin of the step-like character of the discharge curve for
           NaxCoO2-y cathode
    • Authors: Janina Molenda et al
      Abstract: Functional Materials Letters, Ahead of Print. This paper shows electronic approach to an explanation of the step-like character of the discharge/charge curve of Na/Na+/NaxCoO2-y battery. On a basis of comprehensive experimental studies of physicochemical properties of NaxCoO2-y cathode material (XRD, electrical conductivity, thermoelectric power, electronic specific heat) supported by calculations performed using the Korringa–Kohn–Rostoker method with the coherent potential approximation to account for chemical disorder, it has been shown that the observed step-like character of the discharge curve reflects the variation of the chemical potential of electrons (Fermi level) in the density of states of NaxCoO2-y, which is anomalously perturbed by a presence of the oxygen vacancy defects and sodium ordering.
      PubDate: Tue, 16 Sep 2014 08:45:01 GMT
      DOI: 10.1142/S1793604714400098
  • Synthesis and electro-magnetic properties of flower-like Fe2O3-Ag
           nanocomposite using direct subsidence loading method
    • Authors: Xing Zhou et al
      Abstract: Functional Materials Letters, Ahead of Print. Novel flower-like Fe2O3/Ag nanocomposites were synthesized by a simple direct subsidence loading methocccd. The composition and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SEAD) techniques. The Ag nanoparticles which loaded on the surface of petals exhibit spherical morphology. Further, the magnetic and electrical conductive properties reveal the well controllable performance. Room temperature magnetic measurement of the flower-like nanocomposites demonstrated its ferromagnetic properties and the saturation magnetization (Ms) decreased from 0.6 to 0.11 emu/g.
      PubDate: Tue, 16 Sep 2014 08:45:01 GMT
      DOI: 10.1142/S1793604715500137
  • Electrocatalytic oxidation of ethanol in acid medium: enhancement of
           activity of vulcan-supported Platinum-based nanoparticles upon
           immobilization within nanostructured zirconia matrices
    • Authors: Iwona A. Rutkowska et al
      Abstract: Functional Materials Letters, Ahead of Print. Composite electrocatalytic materials that utilize carbon (Vulcan) supported Pt or PtRu nanoparticles dispersed within thin films of zirconia (ZrO2) are considered here for oxidation of such a biofuel as ethanol in acid medium. The systems were characterized using electrochemical techniques as well as transmission electron microscopy. The enhancement of activity was clearly evident upon comparison of the respective voltammetric and chronoamperometric current densities recorded (at room temperature in 0.5 mol dm-3H2SO4 containing 0.5 mol dm-3 ethanol) using the Vulcan supported Pt and PtRu catalysts in the presence and absence of zirconia. In all cases, the noble metal loading was the same, 100 μg cm-2. Apparently, the existence of large population of hydroxyl groups (originating from zirconia) in the vicinity of Pt-based catalyst, in addition to possible specific interactions between zirconia and the ruthenium component of PtRu, facilitated the oxidative removal (from Pt) of the passivating (e.g., CO) reaction intermediates (adsorbates). By utilizing carbon supported, rather than bare or unsupported, Pt or PtRu nanoparticles (dispersed within the semiconducting zirconia), the overall charge distribution at the electrocatalytic interface was improved.
      PubDate: Fri, 05 Sep 2014 02:56:47 GMT
      DOI: 10.1142/S1793604714400050
  • Resistive switching effect of Ag/MoS2/FTO device
    • Authors: Bai Sun et al
      Abstract: Functional Materials Letters, Ahead of Print. The electric-pulse-driven resistance change of metal/oxides/metal structure, which is called resistive switching effect, is a fascinating phenomenon for the development of next generation non-volatile memory. In this work, an outstanding bipolar resistive switching behavior of Ag/MoS2/fluorine-doped tin oxide (FTO) device is demonstrated. The device can maintain superior reversible stability over 100 cycles with an OFF/ON-state resistance ratio of about 103 at room temperature.
      PubDate: Mon, 25 Aug 2014 01:56:49 GMT
      DOI: 10.1142/S1793604715500101
  • Using woven carbon fiber fabric to construct gradient porous structure for
           passive direct methanol fuel cells
    • Authors: Wei Yuan et al
      Abstract: Functional Materials Letters, Ahead of Print. The passive direct methanol fuel cell (DMFC) is a promising candidate power source for portable applications but has to deal with many technical challenges before practical use. This study presents a preliminary investigation on the use of a woven carbon fiber fabric (WCFF) for constructing a gradient porous structure based on the traditional design. The WCFF, carbon paper and carbon-black micro porous layer (MPL) combine into a carbon-based assembly swhich acts as a mass-transfer-controlling medium at the anode of a passive DMFC. Results show that this novel setup is able to significantly improve the cell performance and facilitate high-concentration operation. A maximum power density of 16.4 mWcm-2 is obtained when two layers of the WCFF are used at a methanol concentration of 8M. This work provides an effective method for using concentrated methanol with no need for major change of the fuel cell configuration.
      PubDate: Mon, 25 Aug 2014 01:56:49 GMT
      DOI: 10.1142/S1793604715500095
  • Facile fabrication of ZnO nanorods/ZnO nanosheet–spheres hybrid
           photoanode for dye-sensitized solar cells
    • Authors: Te Bai et al
      Abstract: Functional Materials Letters, Ahead of Print. Zinc oxide (ZnO) nanorods (ZNRs) and hierarchical ZnO nanosheet–spheres (ZNSs) were prepared through a simple aqueous chemical growth process and a low-temperature solid-phase method, respectively. The prepared ZNRs and ZNSs were mixed to obtain a composite structure by using a circumference oscillator. After structure and morphology characterizations via X-ray diffraction and scanning electron microscopy, the mixture of ZNRs and ZNSs was used as a photoanode in dye-sensitized solar cells (DSSCs). Photovoltaic performance and optimal mixture ratio were investigated. The results indicated that the photovoltaic properties of DSSCs depended on the microstructures, morphologies and mixture ratios of the electrodes. In addition, the mixture of ZNRs and ZNSs (molar ratio of 1:12) yielded an overall light conversion efficiency of 6.02%, with a fill factor of 65.0%, a short-circuit current of 13.49 mA/cm2, and an open-circuit voltage of 0.69 V. These values are higher than those of pure ZNRs or pure ZNSs.
      PubDate: Mon, 25 Aug 2014 01:56:48 GMT
      DOI: 10.1142/S1793604715500125
  • Graphene-wrapped CuInS2 composites for efficient dye-sensitized solar
    • Authors: Lei Zhou et al
      Abstract: Functional Materials Letters, Ahead of Print. Graphene-wrapped CuInS2 composites were synthesized via a facile hydrothermal approach. The as-synthesized products were characterized by scanning electron microscope and transmission electron microscopy and the reduction of GO were confirmed by Raman spectroscopy. Graphene-wrapped CuInS2 composites exhibit excellent electrocatalytic activity for the triiodide reduction due to the improved conductivity and the synergetic catalysis of CuInS2 and graphene. The graphene-wrapped CuInS2 composites were exploited as counter electrode for dye-sensitized solar cells and therefore achieved a power conversion efficiency of 6.4%, which is comparable to that of Pt CE (6.9%).
      PubDate: Mon, 25 Aug 2014 01:56:48 GMT
      DOI: 10.1142/S1793604715500113
  • Preparation of Y2O3:Eu3+, Tb3+ nanopowders with tunable luminescence by
           ammonium bicarbonate co-precipitation method
    • Authors: Hui Shi et al
      Abstract: Functional Materials Letters, Ahead of Print. Y2O3:Eu3+, Tb3+ nanopowders were prepared by co-precipitation method with NH4HCO3 as precipitant. The nanopowders with different calcined temperatures and Eu3+/Tb3+ doped ratio were characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results showed that the nanopowders calcined at 1100°C for 2 h had a uniform distribution, high purity and good dispersibility. The particle size was in the range of 60–80 nm. The excitation spectra of Eu3+/Tb3+ co-doped phosphors were wide. The phosphors could emit the green light at the peak of 543 nm and the red light at the peak of 611 nm simultaneously under 276 nm or 300 nm excited. Because of the energy transfer between Tb3+ and Eu3+, the 543 nm emission of Tb3+ ion was weakened while the 611 nm emission of Eu3+ enhanced. The emissive colors of Y2O3:Eu3+, Tb3+ nanopowders could be adjusted from yellow-green to orange-red by changing the Eu3+/Tb3+ doping ratio.
      PubDate: Wed, 13 Aug 2014 02:03:30 GMT
      DOI: 10.1142/S179360471550006X
  • Development of quasi-two-dimensional Nb2O5 nanoflakes with
           thickness-depended electro-chemical properties
    • Authors: Serge Zhuiykov et al
      Abstract: Functional Materials Letters, Ahead of Print. Quasi-two-dimensional (Q2D) Nb2O5 nanoflakes were synthesized by combined sol–gel/exfoliation method with the average thickness of 10–25 nm. Their structural, surface- and electro-chemical properties were closely studied and analyzed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), conductive atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques.
      PubDate: Wed, 13 Aug 2014 02:03:29 GMT
      DOI: 10.1142/S1793604715500071
  • Basalt fiber reinforced porous aggregates-geopolymer based cellular
    • Authors: Xin Luo et al
      Abstract: Functional Materials Letters, Ahead of Print. Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress–strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress–strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.
      PubDate: Wed, 13 Aug 2014 02:03:29 GMT
      DOI: 10.1142/S1793604715500058
  • Enhanced thermoelectric properties of n-type Bi2Te2.7Se0.3 by indium and
           sodium co-doping
    • Authors: Xingkai Duan et al
      Abstract: Functional Materials Letters, Ahead of Print. Bi(1.98-x)In0.02NaxTe2.7Se0.3 (x = 0, 0.02, 0.04, 0.06) and Bi2Te2.7Se0.3 alloys were prepared by vacuum melting and hot pressing methods. The phase structure of the bulk samples were characterized by X-ray diffraction. Effects of indium and sodium co-substitutions for bismuth on the electrical and thermal transport properties were investigated in the temperature range of 298–473 K. Indium and sodium co-doping can enhance the carrier concentration, and accordingly the electrical conductivity can be improved effectively. The Seebeck coefficients of the co-doped samples have not been derogated strongly. The power factors are enhanced for the Bi(1.98-x)In0.02NaxTe2.7Se0.3 (x = 0.02) within the whole testing temperature range. The Bi(1.98-x)In0.02NaxTe2.7Se0.3 (x = 0.02) samples have the lower thermal conductivity due to reduction in lattice thermal conductivity, which leads to a great improvement in the thermoelectric figure of merit ZT. The highest ZT of the sample can reach 0.87 at 398 K.
      PubDate: Wed, 13 Aug 2014 02:03:28 GMT
      DOI: 10.1142/S1793604715500083
  • Harvesting uniform and high bright Sm complex via microwave ultrasound
    • Authors: Jing Tao et al
      Abstract: Functional Materials Letters, Ahead of Print. The uniform ball-like luminescence down-shifting (LDS) Sm(TTA)3Phen materials have been synthesized by microwave ultrasonic method. Microwave ultrasonic plays a synergistic effect of microwave with ultrasonic, including thermal effect, dipole vortex and air bombard make the particles aggregation reach to the lowest energy. Through this method, we successfully synthesised 1–4 μm ball-like uniform Sm(TTA)3Phen clusters. The Sm(TTA)3Phen can transfer violet light to red-orange flourescence with a feature large Stokes shift and completely avoid self-absorption losses.
      PubDate: Wed, 06 Aug 2014 07:46:45 GMT
      DOI: 10.1142/S1793604715500046
  • Sol–gel synthesis, structural and electrical properties of Li2CoSiO4
           cathode material
    • Authors: Michał Świętosławski et al
      Abstract: Functional Materials Letters, Ahead of Print. Polyanionic cathode materials for lithium-ion batteries start to be considered as potential alternative for layered oxide materials. Among them, Li2CoSiO4, characterized by outstanding capacity and working voltage, seems to be an interesting substitute for LiFePO4 and related systems. In this work, structural and electrical investigations of Li2CoSiO4 obtained by sol–gel synthesis were presented. Thermal decomposition of gel precursor was studied using EGA (FTIR)-TGA method. Chemical composition of the obtained material was confirmed using X-ray diffraction and energy-dispersive X-ray spectroscopy. The morphology of β-Li2CoSiO4 was studied using transmission electron microscopy. High temperature electrical conductivity of Li2CoSiO4 was measured for the first time. Activation energies of the electrical conductivity of two Li2CoSiO4 polymorphs (β and γ) were determined. The room temperature electrical conductivity of those materials was estimated as well.
      PubDate: Mon, 21 Jul 2014 01:33:10 GMT
      DOI: 10.1142/S1793604714400013
  • Oxygen storage-related properties of substituted BaLnMn2O5+δ A-site
           ordered manganites
    • Authors: Konrad Świerczek et al
      Abstract: Functional Materials Letters, Ahead of Print. In this work, we present results showing modification of the oxygen storage-related properties of perovskite-type oxides based on BaYMn2O5+δ, having A-site layer-type cation order. Y3+ is the lightest among suitable cations, which allows to obtain such the structural order, and at the same time, it provides the highest theoretical oxygen storage capacity. However, substitution of Y3+ by Sm3+ cations may be beneficial, and BaY0.5Sm0.5Mn2O5+δ material shows enhanced reduction kinetics. Furthermore, partial substitution of Ba2+ by Sr2+ increases reversible oxygen storage capacity, but at the same time slows down the reduction speed. In addition, for higher concentration of strontium, it is not possible to obtain single phase materials.
      PubDate: Mon, 21 Jul 2014 01:33:10 GMT
      DOI: 10.1142/S1793604714400049
  • Understanding sodium versus lithium intercalation potentials of electrode
           materials for alkali-ion batteries
    • Authors: M. Elena Arroyo-De Dompablo
      Abstract: Functional Materials Letters, Ahead of Print. Differences in average voltages for the alkali ion intercalation (Li, Na) in a variety of electrode materials are investigated. The average Li and Na insertion potentials in the cavities of □ReO3-perovskite, ramsdellite-□Ti2O4, layered-□2A2Ti3O7 (A = Li, Na) and NASICON-□Na3Ti2(PO4)3 have been calculated by first principles calculations at the density functional theory level. The results identify the type of site occupied by the inserted ion as the relevant structural parameter. Occupation of large sites (c.n. = 12, 8) might yield Na insertion voltages higher than Li ones. On the other extreme, occupation of tetrahedral sites raises the Li insertion voltage as much as 0.8 V above the Na one. For octahedral sites the higher polarizing character of Li ions vs. Na ions acts as a key-factor to bring the Li intercalation voltage above that of Na intercalation.
      PubDate: Mon, 21 Jul 2014 01:33:09 GMT
      DOI: 10.1142/S1793604714400037
  • Synthesis of Sb2S3 films on conducting substrate and its application In
           hybrid solar cell devices
    • Authors: Yange Zhang et al
      Abstract: Functional Materials Letters, Ahead of Print. Antimony sulfide (Sb2S3) films on indium-doped tin oxide (ITO) glass substrates are easily synthesized by a solvothermal method from Sb ultrathin films and S powder as antimony and sulfur source, respectively. The crystalline Sb2S3 films were characterized using X-ray powder diffraction (XRD) and Raman spectroscopy. The Sb2S3 films are composed of micro-flakes of Sb2S3. The composite of Sb2S3 film and ITO substrate were used to fabricate the solar cell device (ITO/Sb2S3:P3HT/Au), and I–V measurement of the device was performed. Under the optimized condition, the solar conversion efficiency is 0.0026% at 1 sun illumination.
      PubDate: Mon, 21 Jul 2014 01:33:09 GMT
      DOI: 10.1142/S1793604715500034
  • Characterization of NASICON-type Na solid electrolyte ceramics by
           impedance spectroscopy
    • Authors: E. Kazakevičius et al
      Abstract: Functional Materials Letters, Ahead of Print. Na solid electrolytes are cheaper than the ones of Li and could be of interest to apply in secondary batteries and gas sensors. In the present work, the NASICON-type Na1.3Ti1.7Al0.3(PO4)3 compound has been synthesized by Pechini method and the phase purity of the compound was confirmed by XRD. Ceramics of the compound were prepared in several different sintering temperatures and the morphology of the samples was examined by SEM. The investigation of the electrical properties was performed in 10 Hz to 3⋅109 Hz and 300–500 K frequency and temperature ranges by means of impedance spectroscopy. The impedance spectra were analyzed and observed dispersions were related to microstructure of the ceramics.
      PubDate: Mon, 21 Jul 2014 01:33:09 GMT
      DOI: 10.1142/S1793604714400025
  • Enhanced open circuit voltage in photovoltaic effect of polycrystalline La
           and Ni co-doped BiFeO3 film
    • Authors: Zeng-Wei Peng et al
      Abstract: Functional Materials Letters, Ahead of Print. Photovoltaic (PV) effect of polycrystalline Bi0.975La0.025Fe0.975Ni0.025O3 (BLFNO) film grown on Pt(111)/Ti/SiO2/Si(001) substrate using sol–gel method has been investigated. The BLFNO film possesses good ferroelectric property and large twice-remanent polarization. It is found that PV response exhibited a strong dependence on the potential of top indium tin oxide (ITO) and bottom Pt electrode. The open circuit voltage is -0.67 V when the potential of ITO electrode is higher than that of Pt electrode and 0.45 V when the potential of ITO electrode is lower than that of Pt electrode. This can be interpreted by the variation of barrier heights at both ITO/BLFNO and BLFNO/Pt interfaces.
      PubDate: Fri, 11 Jul 2014 06:27:23 GMT
      DOI: 10.1142/S1793604715500022
  • Resistive switching of multiferroic BiCoO3 nanoflowers
    • Authors: Bai Sun et al
      Abstract: Functional Materials Letters, Ahead of Print. Multiferroic BiCoO3 nanoflowers were synthesized by a hydrothermal process. The BiCoO3 nanoflowers show superior bipolar resistive switching characteristics. The typical current–voltage (I–V) characteristics of the Ag/BiCoO3/Ag structures exhibit an extreme change in resistance between high resistance state (HRS) or "OFF" state and low resistance state (LRS) or "ON" state with ON/OFF ratio ~ 105.
      PubDate: Thu, 10 Jul 2014 01:24:44 GMT
      DOI: 10.1142/S1793604715500010
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