Subjects -> PHYSICS (Total: 857 journals)
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ELECTRICITY AND MAGNETISM (10 journals)

Showing 1 - 10 of 10 Journals sorted alphabetically
Advanced Electromagnetics     Open Access   (Followers: 15)
IEEE Electromagnetic Compatibility Magazine     Full-text available via subscription   (Followers: 14)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 1)
IEEE Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 1)
IEEE Transactions on Electromagnetic Compatibility     Hybrid Journal   (Followers: 30)
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control     Hybrid Journal   (Followers: 8)
International Journal of Bioelectromagnetism     Open Access  
International Journal of Electromagnetics and Applications     Open Access   (Followers: 3)
Journal of Electroceramics     Hybrid Journal  
Magnetochemistry     Open Access  
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Journal of Electroceramics
Journal Prestige (SJR): 0.427
Citation Impact (citeScore): 1
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-8663 - ISSN (Online) 1385-3449
Published by Springer-Verlag Homepage  [2467 journals]
  • Effects of ZBS addition on crystallization, microstructure and dielectric
           properties of low temperature co-fired Mg2SiO4-CaTiO3 ceramics

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      Abstract: Abstract The 0.9Mg2SiO4-0.1CaTiO3 (MSCT) ceramics with 60ZnO-20B2O3-20SiO2 glass (ZBS) and LiF compound additives were prepared by solid-state reaction method. The effects of different ZBS contents on the phase, densification temperature, surface morphology and dielectric properties of MSCT ceramics were studied. The results show that ZBS can inhibit the reaction between LiF and CaTiO3, which improve the surface morphology and reduce the sintering temperature of MSCT ceramics. The sample of MSCT with 2wt%ZBS-1.5wt%LiF sintered at 900 °C for 90 min shows excellent microwave dielectric properties: εr = 9.26, Q × f = 68,580 GHz (at 15.5 GHz) and τf = -1.49 ppm/ °C. There is no obvious element diffusion at the co-firing interface between dielectrics and Ag electrodes, indicating it is a promising candidate for LTCC applications.
      PubDate: 2023-01-19
       
  • Phase transition and electrical properties of high performance, high
           temperature Bi(mg,Ti)O3-PbTiO3-PbZrO3 relaxor ferroelectric ceramics

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      Abstract: Abstract Traditional Pb(Mg1/3Nb2/3)O3-PbTiO3 based relaxor ferroelectrics have attracted much attention. However, the relatively low Tm restricts their application in the high temperature range. In the present study, a novel (0.8-x)Bi(Mg1/2Ti1/2)O3-xPbTiO3-0.2PbZrO3 ((0.8-x)BMT-xPT-PZ) relaxor ferroelectric based on the high temperature BMT-PT piezoelectrics was designed. All samples exhibit pure perovskite structures and the phase structures show a gradual transition from relaxor rhombohedral (R) to normal tetragonal (T) phases via the morphotropic phase boundary (MPB) in the composition range x = 0.36–0.39. The dielectric relaxation behavior can be observed in all samples although a spontaneous normal-relaxor ferroelectric transformation is observed in the T phase region. The x = 0.38 sample exhibits the optimal overall electrical properties with the d33 value of 325 pC/N, the kp value of 0.38, the Tm value of 290 oC. The results indicate that the present studied ternary system has a good potential as high temperature relaxor ferroelectrics.
      PubDate: 2023-01-17
       
  • Actuating performance for functionally graded piezoelectric materials with
           interdigitated electrodes

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      Abstract: Abstract In this article, the actuating performance for functionally graded piezoelectric materials (FGPM) using the \(d_{33}\) mode actuation is investigated. The material properties vary continuously across the thickness direction, according to a fraction volume power law distribution, so that top and bottom surfaces consist of pure PZTG and the mid surface is composed of pure aluminium. The percolation phenomenon is taken into account. The optimization of the interdigitated electrode (IDE) design for FGPM is performed using finite element analysis. Several design parameters (electrodes number, width and spacing) are considered to improve the produced displacement for a cantilever plate, and the use of multilayered IDE is intended. Results are discussed for several distributions of the components in the FGPM thickness. A comparison with the \(d_{31}\) mode actuation is presented.
      PubDate: 2023-01-07
       
  • Synergistic effect of impure/pure graphene oxide and TiO2 fillers on the
           dielectric properties of poly (vinylidene fluoride- hexafluoropropylene)
           for electroadhesive high load bearing applications

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      Abstract: Poly (vinylidene fluoride- hexafluoroproylene) PVDF-HFP has been employed as a host polymer because of its strong chemical resistance, mechanical and dielectric properties and low cost. However, further changes employing other polymers, nanomaterials, additives and fillers to improve the properties of the host polymers are of significant interest. TiO2 has gained a lot of attention because of its high k dielectric and photo catalytic capabilities. Graphene oxide (GO) has received a lot of attention because of its larger mechanical strength, dielectric behavior and other qualities. Using the doctor blade coating process, varied amounts of TiO2 and GO were successfully integrated into PVDF-HFP to form composite films. The XRD result reveals that TiO2/GO has been successfully incorporated into the PVDF-HFP polymer matrix, while FTIR, SEM experiments have demonstrated the effectiveness of TiO2/GO fillers on PVDF-HFP film. AC impedance spectroscopy reveals the dielectric behavior and resistivity of polymer nanocomposite film. The film has been tested for its loading bearing capacity during electroadhesion with different applied voltages. The maximum load bearing capacity based on electroadhesion has been estimated. Graphical abstract
      PubDate: 2023-01-07
       
  • Structural and dielectric properties of microwave dielectric materials
           xBa(Zn1/3Ta2/3)O3 - (1-x)La(Zn1/2Ti1/2)O3

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      Abstract: Abstract The structural, vibrational and microwave dielectric properties of xBa(Zn1/3Ta2/3)O3 - (1-x)La(Zn1/2Ti1/2)O3 [x = 1, 0.7, 0.5, 0.3 and 0] are investigated. The materials are synthesized by the solid-state reaction technique. The crystal structure of the materials is obtained from the Rietveld refinement of the X-ray diffraction (XRD) profile. All other materials except Ba(Zn1/3Ta2/3)O3 (x = 1) are crystallized in monoclinic P21/n symmetry. The crystal structure of Ba(Zn1/3Ta2/3)O3 is trigonal with P-3m1 space group. The vibrational properties of the materials obtained from Raman spectroscopy are correlated with the structural parameters. The microwave dielectric constant εr is maximum for x = 0.5 whereas the quality factor Q.f is maximum for x = 1. The effects of vibrational and structural parameters on the microwave dielectric properties are discussed in detail. The dielectric relaxation and the Ac conductivity of the materials are also studied using the alternating current impedance spectroscopy in the frequency range from 50 Hz to 5 MHz.
      PubDate: 2023-01-04
       
  • Structure and electrical properties in CuO-modified BCZT lead-free
           piezoelectric ceramics

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      Abstract: Abstract Ba0.85Ca0.15Zr0.1Ti0.9O3-x wt% CuO (BCZT-xCu) lead-free piezoelectric ceramics were designed and synthesized using a traditional solid-state reaction method to improve both the relaxor behavior and the electrical properties of BCZT lead-free piezoelectric ceramics. The Cu2+ diffuses into the BCZT lattice and forms ABO3 perovskite solid solution. Additionally, X-ray diffraction patterns and Raman spectra reveal that the introduction of CuO causes phase transition from the O-T phase coexistence to the O phase in BCZT-xCu. SEM displays that BCZT-xCu has a well microstructure at CuO doping amount between 0.5 wt% and 1 wt%. With the increasing CuO content, the orthorhombic-tetragonal (TO-T) phase transition shifted towards higher temperature, while Curie temperature (Tc) shifted towards lower temperature. Moreover, the dielectric diffusivity γ increases from 1.63 to 1.92 as x increases. Results indicate that optimal electrical properties, namely d33 = 315 pC/N, kp = 34%, εr = 3213, tanδ = 2.71%, Pr = 7.45 µC/cm2 and Ec = 2.75 kV/cm are achieved in the 1 wt% CuO added ceramic sintered at 1250°C for 2 h.
      PubDate: 2022-12-09
       
  • Electric field-induced strain mechanism in multi-cationic quenched fired
           BiFeO3-based piezoceramics

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      Abstract: Abstract Piezoceramic composition (1-z) (0.67Bi1.05FeO3–0.33BaTiO3)–zBi(Mg0.5Zr0.5)O3 (z = 0.00−0.10) were framed in this work. Regular firing technique succeeding by quenching method was applied. Effect of Bi(Mg0.5Zr0.5)O3, abbreviated as BMZ, modification on structural and electrical properties were systematically analyzed. A large-field piezoelectric coefficient (Smax/Emax = d33*) of 560 pm/V at 4 kV/mm and relatively small hysteresis (~ 28%) were obtained. The possible enhancement in strain, d33 and Pr values near the optimal compositions z = 0.060, 0.080 can be ascribed to the augmented anharmonicity of lattice vibrations that may facilitate the flexiblity (at unit cell level) of these narrow compositions and triggers the enrichment of piezoelectric properties. A large piezoactuation constant with relatively low hysteresis loss and high working temperature (Tm around 415 οC) without unwanted depolarization temperature Td made the investigated piezomaterial promising for the ceramic actuators’ applications. Unlike BNT-based systems, where mixed ergodic relaxor (ER) and nonergodic relaxor (NR) states are supposed to generate high strains, in the present BF-based ceramics, based on obtained results, BMZ-modified BF-BT materials are hypothesized to spontaneously switch from a high-temperature ER state to a ferroelectric state without transitioning to an intermediary NR state.
      PubDate: 2022-12-06
       
  • Improving bending strength of LTCC materials with low dielectric loss by
           structural design

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      Abstract: Abstract The flake alumina filler is added to improve the bending strength in BaZrO3 (BZ)/BaO-MgO-ZnO-SiO2-B2O3 (BBSMZ) glass for the application of low temperature co-fired ceramics. The effects of flake alumina filler for BaZrO3/BaO-MgO-ZnO-SiO2-B2O3 on phase, microstructure, dielectric and mechanical property are studied. With the increase of flake Al2O3 content, flake Al2O3 phase appears, BaZrO3, BaZr(BO3)2, BaZn2Si2O7 phase decreases, dielectric constant decreases and dielectric loss increases. By adding flake Al2O3, the mechanical strength of the material increases. Under the same sintering conditions, the bending strength (205 MPa) of the laminated sample increased by nearly 60% compared with the same content flake alumina block sample (124 MPa), and increased by 162% compared with the sample without flake alumina (78 MPa). BZ-BBSMZ-5 wt% flake Al2O3 ceramic sintered satisfactorily at 940 °C with tanδ = 4.82*10–4 (10 GHz), εr = 11.66. The bending strength of the sample is 205 Mpa.
      PubDate: 2022-10-12
      DOI: 10.1007/s10832-022-00296-5
       
  • A critical review on crystal structure mechanisms, microstructural and
           electrical performances of Bi0.5Na0.5TiO3—SrTiO3 perovskites

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      Abstract: Abstract The global demand for Bi0.5Na0.5TiO3 (BNT) based perovskite materials with wide-ranging applications in the sensors, detectors, capacitors, random access memories, and environmental fields is on the increase. The Sr2+ doped BNT system has been extensively investigated in the past decade due to its excellent structural, electrical and microstructural applications. This review encompasses the fundamental state-of-the-art development of BNT-based ceramics, focusing on the underlying SrTiO3 (ST) composition and enhanced crystal structure mechanisms. The diffuse phase transition related to the ferroelectric nature of the sample is specifically demonstrated. BNT-ST in various forms like single crystals, thin films, multi-layers, and polycrystals for enhanced piezoelectric and ferroelectric activities were discussed in detail. Finally, these systems' key challenges and future directions are also included. Indeed, this review will propagate more exhaustive research on non-toxic and cost-effective pathways to produce BNT-based components with dynamic properties, which can be applied in several industrial applications with outstanding performance.
      PubDate: 2022-09-28
      DOI: 10.1007/s10832-022-00295-6
       
  • Preparation of LSGM electrolyte via fast combustion method and analysis of
           electrical properties for ReSOC.

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      Abstract: Abstract In this work, we prepared La1 − xSrxGa1−yMgyO3 (LSGM) by the fast combustion method and assessed the electrical properties with respect to the composition and sintering temperature (1200, 1300, and 1400 °C by 6 h) as an electrolyte material for the reversible solid oxide cells (ReSOCs). For the preparation of samples, two different fuels, such as tartaric acid (TA) and citric acid (CA), with corresponding nitrate salts as precursors, were adopted for the fast combustion method (at 500 °C for 10 min). From the X-ray diffractograms, two main phases corresponding to LSGM orthorhombic (space group Imma) and LSGM-cubic (space group Pm-3 m) were identified. From the literature, both structures are reported as high oxygen ion conductive species, but normally they are not reported to appear together. Additionally, in some cases, an isolating (secondary) phase of LaSrGaO4 in a low concentration < 1.98% was observed. The scanning electron microscopy (SEM) studies on samples sintered at 1200 and 1300 °C revealed the smaller grain size and irregular morphology. The SEM micrographs depicted a well-defined superficial morphology with less porosity for the samples sintered at 1400 °C. For comparative analysis, the conductivity (S.cm− 1) was measured at varying temperatures (300–800 °C) for the samples sintered at 1300 and 1400 °C. Because of the large number of insulating phases produced by the incomplete sintering process, the samples sintered at 1300 °C had lower conductivities. A higher conductivity of 0.125 S.cm− 1 was observed for La0.80Sr0.20Ga0.80Mg0.20O3 (LSGM), which was obtained using the citric acid (sintered at 1400 °C), which is in the range of earlier reported similar studies. The observed variation in the conductivity with respect to different phases of LSGM, the influence of the secondary phase, and the wt% of the constituents of LSGM are discussed.
      PubDate: 2022-09-22
      DOI: 10.1007/s10832-022-00294-7
       
  • Effect of grain size on crystal structure and electric properties of
           Bi(Ni2/3Ta1/3)O3-PbTiO3 ferroelectric ceramics

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      Abstract: Abstract The effect of grain size on crystal structure and the ferroelectric, dielectric, and piezoelectric properties of 0.38Bi(Ni2/3Ta1/3)O3-0.62PbTiO3 ceramics was studied herein. By controlling the sintering time, 0.38Bi(Ni2/3Ta1/3)O3-0.62PbTiO3 ceramics with different grain sizes were prepared by the conventional solid-state reaction. It was found that the crystal structure of the ceramics changed slightly with the increase of grain size, from a pure tetragonal perovskite structure to a combination of tetragonal and rhombohedral phases. Both the Curie temperature TC and the depolarization temperature Td of the ceramics decreased with increasing grain size. However, the degree of dielectric relaxation first increased and then decreased, with the relaxation factor γ ranging from 1.35 to 1.87. The remnant polarization Pr and coercive field EC also first increased and then decreased, whereas the strain increased with the increase of grain size. The high field strain coefficient d*33 and piezoelectric coefficient d33 both increased with the increase of grain size. However, in this ceramic system, the electromechanical coupling coefficient kp and mechanical quality factor Qm changed independently of the variation in grain size.
      PubDate: 2022-09-06
      DOI: 10.1007/s10832-022-00293-8
       
  • Effect of Cu2+ substitution on structural, electrical and dielectric
           properties of bismuth vanadate by impedance spectroscopic studies

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      Abstract: Abstract Polycrystalline samples of Bi4V2(1-x)Cu2xO11-3× were prepared by solid state reaction method. Thrust of the work is to stabilize high temperature conducting γ-phase at room temperature. XRD and DSC analysis indicates orthorhombic ‘α’ phase for x ≤ 0.08 to tetragonal γ-phase transition for x = 0.1, at room temperature. Variations of real and imaginary impedance as well as complex electrical modulus with frequency are reported. Experimental impedance spectroscopic data was theoretically fitted and equivalent circuits are proposed. Nyquist plots revealed contribution from grain as well as interface. Variations of impedance, dielectric permittivity and AC conductivity as a function of frequency at selected temperatures are reported. The AC conductivity was fitted with Jonscher’s power law and the power law exponent (η) was found to be < 1, indicating that the conduction process follows CBH mechanism. The dielectric behaviour was found to follow UDR model. Cu2+ ions was observed to introduce defects and oxygen vacancies, space charge accumulation, reduction in dielectric permittivity and increase in the conductivity as high as up to 0.45 S·cm−1 for the expected γ-phase.
      PubDate: 2022-08-06
      DOI: 10.1007/s10832-022-00290-x
       
  • Tunning the dielectric and energy storage properties of high entropy
           ceramics (Bi0.2Na0.2K0.2La0.2Sr0.2)(Ti1-xScx)O3 by Sc-doping at B-site in
           perovskite structure

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      Abstract: Abstract The (Bi0.2Na0.2K0.2La0.2Sr0.2)(Ti1-xScx)O3 (BNKLST-xSc) high entropy ceramics (HECs) have been successfully synthesized via a citrate acid method. The effects of Sc-doping on the lattice structure, microstructural morphology, dielectric and energy-storage properties of HECs are comprehensively investigated. The results indicate that although Sc3+ doped at B-site does not alternate the perovskite structure of BNKLST with a single phase, it results in lattice expansion and weakened bonding in TiO6 octahedron. The dielectric constant of BNKLST-xSc is reduced while the dielectric relaxation is enhanced with increasing Sc content x, due to the enhanced structural inhomogeneity in nano-regions. In addition, the lattice structure of BNKLST-0.2Sc exhibits ultra-high thermal stability at 30–300 °C, which achieves the maximum energy storage density of 1.094 J/cm3 with an outstanding efficiency better than 80%, accompanying by the mechanical and dielectric losses as low as ~ 10–3. It is suggested that BNKLST-0.2Sc could be promising dielectric materials in capacitors and energy-storage devices with an excellent combination of ultrahigh power density, high energy density, thermal stability as well as low mechanical and dielectric losses.
      PubDate: 2022-08-04
      DOI: 10.1007/s10832-022-00292-9
       
  • Structural, FTIR, optical and photoluminescence investigation of Zn1-xRExO
           nanoparticles for optical and power operation devices

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      Abstract: Abstract Structural, morphological, FTIR, optical and photoluminescence (PL) measurements of Zn1-xRExO nanoparticles with RE = Y, La and x (0.00 ≤ x ≤ 0.20) are reported. The wurtzite structure is confirmed for all samples and the lattice parameters, Zn–O bond length, porosity, crystallite size, lattice strain and residual stress are increased by increasing x to 0.20, but they are higher for La samples than Y. The grain sizes are 180, 330, and 460 nm for the pure, Y and La samples. The addition of RE to ZnO generally shifts FTIR absorption peaks, Debye temperature, and elastic modulus to higher values, but the shift is higher for La samples than Y. Although excitonic energy is constant for all samples, the energy gap Eg was increased by increasing x to 0.20, but it is higher for La samples than Y. Furthermore, the dielectric lattice constant, density of charge carriers, and electrical conductivity are increased by increasing x to 0.10, followed by a decrease to 0.20. The opposite behavior is true for dielectric loss and optical conductivity. The PL intensity shows four continuous visible peaks of near UV, blue, green, and red. Interestingly, the intensity of blue emission is greater than that of near UV, such that [(Iblue/IUV)] > 1]. Furthermore, for x > 0.10 samples, there is another lowest intensity IR emission peak centred at 824 nm (1.507 eV). These results are well explained and strongly recommend the RE doped samples for the applications of optoelectronic and high-power operating devices. To our knowledge, the present investigation probably has never been reported elsewhere.
      PubDate: 2022-08-02
      DOI: 10.1007/s10832-022-00291-w
       
  • Tensors symmetry of crystalline nonlinear piezoelectric materials

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      Abstract: Abstract The new technologies such as the fifth generation of telecommunications (5G) and the internet of things (IoT) present a set of demanding technical requirements at device level that can be reached through devices based on piezoelectric materials using nonlinear effects to increase their performance. However, in the literature can not be found a physics formulation for the unified nonlinear effects of these materials that allow an easy implementation in FEM simulators. Thus, in this work we use the stress-charge formulation to obtain the transformation laws, the unique components of the higher order tensors and the equations of state, which unify the nonlinear phenomena of the piezoelectric effect reported experimentally and, which can be used to increase the performance of the devices and extend the range of applications based on these materials. In addition, the methodology for their implementation on the main FEM simulators is presented.
      PubDate: 2022-06-27
      DOI: 10.1007/s10832-022-00289-4
       
  • Effect of metal electrodes on the steady-state leakage current in PZT thin
           film capacitors

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      Abstract: Abstract The ferroelectric Ir/PZT/Pt and Au/PZT/Pt capacitor structures are studied by the electron beam induced current (EBIC) technique and the steady-state current–voltage dependencies. EBIC data reveal the change in the local field at the PZT/metal interfaces caused by migration of oxygen vacancies \({V}_{o}^{**}\) under an action of applied electric field. Ir/PZT and Pt/PZT interfaces block \({V}_{o}^{**}\) movement causing their accumulation near the cathode interface. An electrons injection from the metal cathode to the PZT leads to formation of induced p–n junction. The steady-state leakage current in this case is well described by modified equation for the p-n diode, which considers an action of the counter electric field caused by electrons injection. In the case of transparent for oxygen vacancies Au/PZT cathode oxygen vacancies leave the PZT bulk and current–voltage dependence demonstrates a region of negative differential conductivity at high electric fields. The proposed p–n junction formalism can be used for engineering of PZT-based devices.
      PubDate: 2022-06-25
      DOI: 10.1007/s10832-022-00288-5
       
  • Effect of Co2+ substitutions on microstructure and dielectric properties
           of Bi1.5MgNb1.5O7 cubic pyrochlore

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      Abstract: Abstract The attractive bismuth-based cubic pyrochlores possess large dielectric constant, high dielectric tunability, and extremely low dielectric loss. The Bi1.5Mg1-xCoxNb1.5O7 (Co-BMN, x = 0.0–0.5) cubic pyrochlore ceramics were prepared by solid-state reaction. All the Co-BMN ceramics maintained the cubic pyrochlore phase with a preferential (111) orientation. The forbidden (442) diffraction plane was found in Co-BMN pyrochlores. The crystallization of the Co-BMN ceramics was promoted by Co2+ doping modification. The Co-BMN at x = 0.3 achieved the maximum of cell volume, force constant of A-O stretching, and binding energy of Co2+. The dielectric constant of Co-BMN significantly increased due to the larger polarizability of Co2+. The increasing dielectric constant of Co-BMN pyrochlores (x ≤ 0.3) with increasing Co2+ doping was attributed to the displacive disorder of A-site and O’ ions. Co-BMN with moderate Co2+ doping (x ≤ 0.4) presented a low dielectric loss (< 0.0007). The temperature coefficient of dielectric constant of Co-BMN pyrochlores (x ≤ 0.4) increased from -382 ppm/oC to -84 ppm/oC after Co2+ doping. However, high concentration of Co2+ resulted in deterioration of dielectric properties of Co-BMN.
      PubDate: 2022-06-07
      DOI: 10.1007/s10832-022-00287-6
       
  • Transport properties of CuxCo4Sb11.7Te0.3 prepared by solid-state reaction

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      Abstract: Abstract The Skutterudite compounds have been extensively studied worldwide over the past several years for their potential advanced thermoelectric applications in the intermediate temperature range. However, most methods for synthesis of CoSb3 materials require a long-duration heating process and complex equipments. In this study, a simple solid-state reaction method was used to prepare copper-tellurium co-doped CoSb3 ( CuxCo4Sb11.7Te0.3, x = 0-0.4) bulk thermoelectric materials. The obtained samples show enhanced thermoelectric properties compared to Cu-undoped sample. Especially in the case of Cu-doped CoSb3, the compound Cu0.4Co4Sb11.7Te0.3 exhibits a maximal Seebeck coefficient of 234.2 µVK− 1 at 617 K, the sample Cu0.1Co4Sb11.7Te0.3 reaches a power factor of 2012.35 mWm− 1 K− 2 at 715.7 K. Moreover, phonon scattering appears to be enhanced due to the significant reduction in grain size of the samples prepared by the solid-state reaction method, resulting in a minimum thermal conductivity of 1.67 Wm− 1 K− 1. A dimensionless figure of merit (ZT) of 0.68 was obtained for Cu0.3Co4Sb11.7Te0.3 at 716 K. Thus, the solid-state reaction method is a feasible strategy for the preparation of Skutterudite thermoelectric materials.
      PubDate: 2022-06-06
      DOI: 10.1007/s10832-022-00286-7
       
  • Structure–property correlation in (1-y)Bi0.9Ca0.1FeO3-(y)PbTiO3 (0.0
           < y < 1.0) solid solutions

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      Abstract: Abstract The importance of using divalent ion doped BiFeO3 ceramics in-place of pure BiFeO3 informing solid solutions with other ferroelectric materials is emphasized. The phase stability for the (1-y)Bi0.90Ca0.10FeO3-(y)PbTiO3 system in the complete composition range show occurrence of interesting structure modulations. The changes in the crystal unit cell also seem to have significant effects on the microscopic structure. The SEM studies indicate the formation of more than one type of grains in the system. Such coexistence of one type of grains is found to show relaxor type characteristics both in dielectric and magnetic properties. Suitable models are used to explain the origin of the observed bi-relaxor type characteristics. The low temperature ac-magnetic studies suggest stabilization of a predominant spin-glass type characteristics in samples with 0.30 < y < 0.50.
      PubDate: 2022-05-03
      DOI: 10.1007/s10832-022-00285-8
       
  • Oxygen vacancy-induced Al2TiO5 –based multifunctional ceramic
           composites: Electrochemical and optical properties

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      Abstract: Abstract In this study, Al2TiO5 –based multifunctional ceramics were prepared using the spark plasma sintering method within a temperature range of 1573–1773 K. The influence of the sintering temperature on the microstructure, phase composition, and electrochemical and optical properties of the Al2O3-TiO2-Al2TiO5 ceramics was evaluated. The results showed that ceramic composites sintered at T = 1773 K possessed the lowest porosity and optical reflectance (5%) in the visible, UV and infrared wavelength ranges. They were characterized by an average crystallite size of approximately 35 nm and the bandgap of 2.2 eV. Considerable changes in the electronic band structure and density of states inside the bandgap lead to enhanced charge carrier separation and reduced charge transfer resistance (RCT = -1.7).
      PubDate: 2022-04-25
      DOI: 10.1007/s10832-022-00284-9
       
 
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