 Subjects -> ELECTRONICS (Total: 207 journals)
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- Impact of oxygen-containing carbonyl and ether groups on dielectric
properties of poly(oxa)norbornene cyclic olefins
Authors: Chao Wu, Ajinkya A. Deshmukh, Lihua Chen, Rampi Ramprasad, Gregory A. Sotzing, Yang Cao
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Flexible dielectric polymers that can withstand high electric field and simultaneously have high dielectric constant are desired for high-density energy storage. Here, we systematically investigated the impact of oxygen-containing ether and carbonyl groups in the backbone structure on dielectric properties of a series of cyclic olefin. In comparison to the influence of the –CF3 pendant groups that had more impact on the dielectric constant rather than the band gap, the change of the backbone structure affected both the dielectric constant and band gaps. The one polymer with ether and carbonyl groups in the backbone has the largest band gap and highest discharge efficiency, while it has the lowest dielectric constant. The polymer without any ether groups in the backbone has the smallest band gap and lowest discharge efficiency, but it has the highest dielectric constant. Polymers that have no dipolar relaxation exhibit an inversely correlated dielectric constant and band gap. Enhancing the dipolar relaxation through rational molecular structure design can be a novel way to break through the exclusive constraint of dielectric constant and band gap for high-density energy storage.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-31T07:00:00Z
DOI: 10.1142/S2010135X23410059
- Photocatalytic water splitting kinetics of CMV model
Authors: J. H. Hu, C. L. Wang
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The photocatalytic water splitting kinetics has been analyzed in this paper. The experimental data are taken from the published works and fitted with different theoretical models. From the results, we find that the photocatalytic kinetics of water splitting can be described by Capelas-Mainardi–Vaz (CMV) model very well. This suggests that the water splitting kinetics can be regarded as a fractional first-order kinetics of the chemical reaction. Also, we notice that photocatalytic water splitting is not always completely a monotone kinetics process.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-31T07:00:00Z
DOI: 10.1142/S2010135X23500157
- Achieving excellent temperature-stable dielectric properties of
Bi[math]Na[math]TiO3-based lead-free ceramics via doping AgNbO3
Authors: Li-na Liu, Xiao-ming Chen, Xing-xing Wang, Han-li Lian
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The lead-free ceramics (1 [math])(0.94Bi[math]Na[math]Ba[math]TiO3-0.06BiAlO3)-[math]AgNbO3 (denoted as BNBTA-[math]AN) were synthesized via a solid-state sintering method. The effect of AgNbO3 doping amount on dielectric properties of the ceramics was studied systematically. X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscope were used to detect the structure of the ceramics. Temperature-dependent dielectric spectra, frequency-dependent dielectric constant and alternating current (ac) electric conductance at various temperatures were measured. The doping of AgNbO3 greatly reduces dielectric constant around Curie temperature and thus enhances the temperature stability of the dielectric constant. The ceramic BNBTA-0.03AN exhibits excellent temperature-stable dielectric properties with temperature coefficient of capacitance (TCC) [math] 15% between 55[math]C and 418[math]C with temperature window 363[math]C and small changes of dielectric constant and dielectric loss from 100 Hz to 1 MHz at different temperatures. The obtained ceramics are expected to be used in high-temperature capacitors due to its excellent temperature stability.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-31T07:00:00Z
DOI: 10.1142/S2010135X23500169
- Structure and ferroelectric properties of P(VDF-TrFE) films prepared under
different conditions — Effect of filtration of the copolymer solution
Authors: B. Ploss, D. Smykalla, S. Engel
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Vinylidene fluoride-trifluoroethylene copolymer films of molar ratio 70/30 with thickness of about 1 [math]m have been deposited from solution in ethyl methyl ketone to a glass substrate with an aluminum electrode by spin coating. The solution has been filtrated through a PTFE membrane filter with pore size 0.2 [math]m directly before spin coating or it has been used as is (unfiltrated). After deposition of a top electrode, the samples have been polarized by hysteresis loops with an electric field amplitude of about 100 V/[math]m. In samples, annealed at temperature 145[math]C for 3 h, a high remanent polarization of about 7.5 [math]C/cm2 has been achieved, without significant differences between samples fabricated of filtrated or unfiltrated solution. Spherulitic lamella are growing in films fabricated of filtrated solution when they are heated above the melting temperature to 159[math]C for 3 min before the further annealing process at 145[math]C. These films show substantially lower remanent polarization below 4 [math]C/cm2. Pyroelectric images recorded with a pyroelectric laser scanning microscope show that the spherulites have very small pyroelectric activity, i.e., the spherulites consist of flat-on lamella. In contrast, no spherulitic lamella are growing in films fabricated of unfiltrated solution heated above the melting temperature, melted and annealed under the same conditions. An explanation for this observation is that filtrating changes the structure of the copolymer in solution from polymer coil to rod. Copolymer rods deposited on a substrate will crystallize in flat-on lamella when heated above the melting temperature, in contrast to copolymer coils which crystallize in edge-on lamella.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-25T07:00:00Z
DOI: 10.1142/S2010135X23410060
- Probing atomic-scale structure of dielectric ceramics with scanning
transmission electron microscopy
Authors: Min Zhang, Rui Wei, Jinquan Zeng, Yuan-Hua Lin
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
High performance dielectric capacitors are ubiquitous components in the modern electronics industry, owing to the highest power density, fastest charge-discharge rates, and long lifetime. However, the wide application of dielectric capacitors is limited owing to the low energy density. Over the past decades, multiscale structures of dielectric ceramics have been extensively explored and many exciting developments have been achieved. Despite the rapid development of energy storage properties, the atomic structure of dielectric materials is rarely investigated. In this paper, we present a brief overview of how scanning transmission electron microscopy (STEM) is used as a tool to elucidate the morphology, local structure heterogeneity, atomic resolution structure phase evolution and the correlation with energy storage properties, which provides a powerful tool for rational design and synergistic optimization.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-25T07:00:00Z
DOI: 10.1142/S2010135X23430014
- Establishment of magneto-dielectric effect and magneto-resistance in
composite of PLT and Ba-Based U-type hexaferrite
Authors: Kanika Aggarwal, Madan Sharma, Shubhpreet Kaur, Vishal Arora, Indu Sharma, Rakesh Kumar, Anupinder Singh
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
We are examining the behavior of a composite made of ferroelectrics with strong dielectric properties and ferrites with magnetic properties due to the rising need for materials for multipurpose devices. Many application avenues will be favored by the pairing of these materials’ individual qualities with one another. Perovskite and [math]-type hexaferrite composite materials have been chosen for this study based on their magnetic and dielectric properties. The composites, (1[math]) PLT[math] (Ba[math]Nd[math] ) 4 Co2 Fe[math] O[math] where [math] = 0.52, 0.54, 0.56, 0.58 are prepared by solid state reaction method and phase formation was examined. Consideration has been given to the magnetic, dielectric, and magneto-dielectric properties. This work has established the link between the electric and magnetic domains while applying electric and magnetic forces to the materials. The magneto-dielectric research revealed magneto-electric coupling in all of the samples. However, the sample shows the maximum coupling for [math] = 0.54 with MDR% values of 93.17%, which might be because this sample appears to have a high magneto-resistance (161%).
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-25T07:00:00Z
DOI: 10.1142/S2010135X23500133
- Microstructure, domain structure, ferroelectric and piezoelectric
properties of textured bismuth-containing ceramics
Authors: E. I. Sitalo, O. A. Bunina, V. G. Smotrakov, N. V. Malomyzheva, N. A. Boldyrev
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
In this report, the processes of texture formation in grain-oriented ferroelectric ceramics based on layer-structured ferroelectric Bi4Ti3O[math](LSBT) prepared by hot forging method are considered. The microstructural and X-ray methods revealed the axial textured formation in ferroelectric ceramic that are used to estimate the orientation factor of ceramics. For the first time, the domain structure changes when poling the anisotropic ferroelectric ceramics are investigated. The anisotropy of electromechanical, piezoelectric and ferroelectric properties of ferroelectric ceramics due to the crystal texture existence in it is studied. The aim of this study is to study the processes of crystalline texture formation in polycrystalline BLSF and to establish the dependence of the electrophysical properties of ceramics on the degree of texturing. Ceramics were textured using the hot stamping (HS) method developed at the Research Institute of Physics. The mechanism of the method is that the workpiece is subjected to uniaxial pressure and free radial deformation occurs due to the plastic flow of the material until the workpiece fills the free volume of the mold, which is created by placing the workpiece in the mold with a gap. The study of the microstructure of ceramics showed that an increase in the firing temperature in the range 950-1050[math]C causes a sharp decrease in porosity and increases the density to 7.95 g/cm3, which is 98% of theoretical. An X-ray analysis was performed and microstructural studies were carried out, which revealed the formation of an axial texture in ceramics. The features of the switching processes of textured ceramics are revealed. The characteristics of the polarization switching of ceramics in the directions parallel and perpendicular ([math]) of the pressure axis during hot processing were obtained from the dielectric hysteresis [math]([math]) loops, i.e., axis axial texture. The [math]-cut ceramics are characterized by a more complete polarization switching, which is associated with the additional orientation of the (001) crystallographic planes in the textured material, as well as the presence of a threshold switching field. In the temperature range from -196 to + 600[math]C, the anisotropy of the electro physical properties of ceramics due to the presence of a crystalline texture in it was studied. The dielectric constant, electrical conductivity, piezoelectric and elastic coefficients were measured for sections of ceramics of different orientations relative to the axis of the texture. The anisotropy of the dielectric constant and electrical conductivity manifests itself weakly at room temperature and increases sharply when approaching the Curie temperature. In the temperature range +20–400[math]C, the high thermal stability of the piezoelectric module [math], measured by the quasistatic method, was established.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-19T07:00:00Z
DOI: 10.1142/S2010135X2350011X
- Preparation and energy storage properties of [math]001[math]-textured
NaNbO3-based ceramics
Authors: Zhengu Chen, Fan Chang, Gengguang Luo, Li Ma, Ju Chen, Jinge Pei, Zhenyong Cen, Qin Feng, Fujita Toyohisa, Nengneng Luo
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Dielectric materials with high energy storage density ([math]) and efficiency ([math]) are expected for energy storage capacitors. In this work, [math]001[math]-textured Na[math]Bi[math]NbO3 (NBN) ceramics were prepared by a templated grain growth technique. The effects of microstructure and orientation degree on dielectric properties, polarization and energy storage performance were investigated. The textured ceramic with an optimized orientation degree (70%) showed a high [math] of 2.4 J/cm3 and [math] of 85.6%. The excellent energy storage properties of textured ceramic originate from the co-effect of interfacial polarization and clamping effect. The results indicate that texture development is a potential candidate to optimize the energy storage properties of functional ceramics.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-10T07:00:00Z
DOI: 10.1142/S2010135X23410011
- High-accuracy characterization of pyroelectric materials: A noncontact
method based on surface potential measurements
Authors: Reinhard Schwödiauer, Simona Bauer-Gogonea, Martin Kaltenbrunner, Volodymyr Tkachenko, Simonetta Grilli
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The characterization of pyroelectric materials is essential for the design of pyroelectric-based devices. Pyroelectric current measurement is the commonly employed method, but can be complex and requires surface electrodes. Here, we present noncontact electrostatic voltmeter measurements as a simple but highly accurate alternative, by assessing thermally-induced pyroelectric surface potential variations. We introduce a refined model that relates the surface potential variations to both the pyroelectric coefficient and the characteristic figure of merit (FOM) and test the model with square-shaped samples made from PVDF, LiNbO3 and LiTaO3. The characteristic pyroelectric coefficient for PVDF, LiNbO3 and LiTaO3 was found to be 33.4, 59.9 and 208.4 [math]C m[math]K[math], respectively. These values are in perfect agreement with literature values, and they differ by less than 2.5% from values that we have obtained with standard pyroelectric current measurements for comparison.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-06T07:00:00Z
DOI: 10.1142/S2010135X23410023
- High piezoelectricity performance in PSBZT ceramic for ultrasonic
transducer
Authors: Shengpeng Han, Guicheng Jiang, Yan Zhu, Yingchun Liu, Hongjun Zhang, Lang Bian, Danqing Liu, Ye Sun, Limei Zheng, Bin Yang, Wenwu Cao
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Lead zirconate titanate (PZT) ceramics possess great potential for practical applications and thus improving their piezoelectric properties is crucial. Pb[math]Sm[math]Ba[math]Zr[math]Ti[math]O3 (PSBZT) ceramics with high Curie temperature and excellent piezoelectric properties were fabricated via a conventional solid-state method, and the effect of Ba[math] doping on the structural, dielectric, piezoelectric and ferroelectric properties was studied in detail. It is shown that doping of Ba[math] significantly enhanced the piezoelectric properties of PSZT, the maximum [math]533 pC/N and [math][math]361[math]C at [math] = 0.02 were acquired. Furthermore, PSZT and PSBZT ceramics were used to prepare single element ultrasonic transducers, and their performance were compared and evaluated. The results demonstrate that the PSBZT ceramic-based transducer possesses better sensitivity and bandwidth than the PSZT ceramic-based transducer.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-05-06T07:00:00Z
DOI: 10.1142/S2010135X23500121
- History and recent progress in ferroelectrets produced in Brazil
Authors: Ruy Alberto Pisani Altafim, Ruy Alberto Corrêa Altafim
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
More than 30 years ago, a group of researchers in Tampere–Finland developed a thin foamed polymeric material for capacitive sensors. Such soft-voided films exhibited electrical charging characteristics, forming a powerful combination, which resulted in a smart-material with ferroelectric properties. The discovery of the electro-thermo mechanical film (ETMF) has sparked the curiosity of the electret community, leading to the development of several studies. At that time, ETMF became known as cellular electrets and, later, as ferroelectrets or piezoelectrets regarding their electromechanical properties. This paper provides a timeline review of the research on ferroelectrets produced in Brazil, between the years 1990 and 2020, towards demonstrating how the interest in the electret electrical charging mechanism has resulted in the use of ferroelectrets with well-controlled cavities for ultrasound applications.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-25T07:00:00Z
DOI: 10.1142/S2010135X23410072
- Composite materials ferropiezoelectric ceramics-polymer for hydroacoustic
receivers
Authors: V. G. Smotrakov, V. V. Eremkin, E. I. Sitalo, N. V. Malomyzheva, N. A. Boldyrev
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The purpose of this work is to study the processes of interfacial interactions, their influence on the piezoelectric properties in highly elastic composite structures, to establish the patterns that determine the volume-sensitive piezoelectric characteristics of composites and to create effective piezoelectric materials for hydroacoustic receiving devices. In the process of this work, the development of a method for obtaining anisotropic ferropiezoelectric ceramics, the development of methods for the preparation of perfect ceramic powders and composite materials based on thermoplastic fluoropolymers and the study of composite materials based on lead–calcium titanate were carried out. As a result of the study, the dependences of the hydrostatic parameters of the composites on the degree of filling, particle size distribution, piezoelectric anisotropy of the active phase and the elastic properties of the polymer matrix were established. Composite materials were based on ceramics of the PT–CT system and thermoplastic fluoropolymers F-2ME, F-62, F-2N with a degree of filling with a ceramic phase from 30 to 60% vol. The dependences of the hydrostatic piezoelectric moduli [math] and [math], and the quality factor [math] on the degree of filling of the composite for polymers F-62 and F-2ME with different average sizes of ceramic particles are plotted. It has been established that the maximum values [math] = 119.1⋅10[math]V⋅m/N and the quality factor [math] = 6074⋅10[math] m2/N are achieved for a polymer with a higher elastic compliance (F-62) at a degree of filling of 60% vol. and the use of granular filler.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-21T07:00:00Z
DOI: 10.1142/S2010135X23500078
- Ferroelectricity in biological building blocks: Slipping on a banana
peel'
Authors: Syed A. M. Tofail
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Ferroelectricity in biological system has been anticipated both theoretically and experimentally over the past few decades. Claims of ferroelectricity in biological systems have given rise to confusion and methodological controversy. Over the years, a “loop” of induced polarization in response to a varying applied electrical field and a consequent polarization reversal has prompted many researchers to claim ferroelectricity in biological structures and their building blocks. Other observers were skeptical about the methodology adopted in generating the data and questioned the validity of the claimed ferroelectricity as such, “loop” can also be obtained from linear capacitors. In a paper with somewhat tongue-in-cheek title, Jim Scott showed that ordinary banana peels could exhibit closed loops of electrical charge which closely resemble and thus could be misinterpreted as ferroelectric hysteresis loops in barium sodium niobate, BNN paraphrasing it as “banana”. In this paper, we critically review ferroelectricity in biological system and argue that knowing the molecular and crystalline structure of biological building blocks and experimenting on such building blocks may be the way forward in revealing the “true” nature of ferroelectricity in biological systems.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-17T07:00:00Z
DOI: 10.1142/S2010135X23410047
- Preparation and acoustic properties of high-temperature acoustic emission
sensor based on La3Ga5SiO[math] crystal
Authors: Jingxiang Si, Changhong Yang, Rui Guo, Yifan Wu, Xiujuan Lin, Shifeng Huang
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
With the rapid development of modern industries, the high-temperature piezoelectric sensors that can work in extreme environments are in great demand. In this work, langasite (La3Ga5SiO[math], LGS), as a high-temperature piezoelectric crystal with stable electro-elastic performance, is used as core element, and air and porous Al2O3 are selected as backing layers respectively to prepare two kinds of high-temperature acoustic emission (AE) sensors. The detection sensitivities at 25-500[math]C are analyzed by the ball falling test and Hsu–Nielsen experiment. Under the condition of 25–500[math]C, the received amplitude signals by both sensors are maintained above 90 dB stimulated by the ZrO2 ceramic ball dropping. In the Hsu–Nielsen experiment, as the temperature rising from 25[math]C to 500[math]C, the signal amplitude of sensor with air backing layer decays from 447 mV to 365 mV, while the signal amplitude varies from 270 mV to 203 mV for the sensor with porous Al2O3 backing layer. Significantly, compared with the bandwidth of the air-backing sensor (37–183 kHz), the sensor with porous Al2O3 backing layer broadens bandwidth to 28–273 kHz. These results show that both these AE sensors have strong and stable response ability to AE signals at high-temperature of 500[math]C. Therefore, piezoelectric AE sensor based on LGS has great potential application in the field of high-temperature structural health monitoring.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-17T07:00:00Z
DOI: 10.1142/S2010135X23420018
- Ferroelectric and piezoelectric properties of lead-free
Li[math](K[math]Na[math])[math]NbO3 thin films
Authors: Xinyu Bu, Changhong Yang, Mengjia Fan, Wenxuan Wang, Xiujuan Lin, Shifeng Huang
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Lead-free (K[math]Na[math])NbO3 (KNN) and Li[math](K[math]Na[math])[math]NbO3 (LKNN) thin films were fabricated by a sol-gel method. The effects of Li substitution on crystal structure, microstructure and electrical properties of KNN film were systematically studied. Li doping can enhance the ferroelectric and piezoelectric properties of KNN film. Compared with pure KNN film, the LKNN film possesses larger remanent polarization ([math] [math] 9.3 [math]C/cm2) and saturated polarization ([math] [math] 41.2 [math]C/cm2) and lower leakage current density ([math] 10[math]A/cm2 at 200 kV/cm). Meanwhile, a typical butterfly shaped piezoelectric response curve is obtained in the LKNN film with a high piezoelectric coefficient ([math] [math] 105 pm/V). Excellent fatigue resistance ([math] 109 switching cycles) and aging resistance ([math] 180 days) demonstrate the long-term working stability of LKNN film. These findings indicate that KNN-based lead-free piezoelectric films have a broad application prospect in microelectromechanical systems (MEMS).
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-17T07:00:00Z
DOI: 10.1142/S2010135X23500091
- High recoverable energy storage density of Na[math]Bi[math]TiO3 lead-free
ceramics modified by Bi(Mg[math]Hf[math])O3
Authors: Kaiyuan Wang, Wenhua Li, Xingui Tang, Siyuan Zhang, Yansong Zhang, Jia Hu, Zhihao Shen, Yanping Jiang, Xiaobin Guo
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Enhancing the availability and reliability of dielectric ceramic energy storage devices is of great importance. In this work, (1-[math])Na[math]Bi[math]TiO3–[math]Bi(Mg[math]Hf[math])O3 (NBT–[math]BMH) lead-free ceramics were created utilizing a solid-state reaction technique. All NBT–[math]BMH ceramics have a single perovskite structure. With increasing BMH doping, the grain size shrinks drastically, which greatly enhances the breakdown electric field (310 kV/cm at [math] = 0.25). Additionally, the relaxation behaviors of NBT–[math]BMH ceramics with high BMH content are more remarkable. Among all designed components, the NBT–0.25BMH ceramic exhibits the best energy storage performance with a high [math] of 4.63 J/cm3 and an [math] of 75.1% at 310 kV/cm. The NBT–0.25BMH ceramic has exceptional resistance to fluctuations in both frequency (5–500 Hz) and temperature (30–100[math]C). Charge–discharge test shows that the NBT–0.25BMH ceramic has a quick discharge rate ([math] 110 ns). With these properties, the NBT–0.25BMH ceramic may have applications in microdevices as well as in ultra-high power electronic systems.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-07T07:00:00Z
DOI: 10.1142/S2010135X2350008X
- Domain wall state diagram for SrTiO3/BaTiO3 superlattice structures
Authors: Yimei You, Fengjuan Yang, Pingping Wu
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The domain wall structure of ferroelectric/paraelectric superlattices can be much more complex due to the influence of the superlattice stacking structure, the in-plane strain induced by the substrate and environmental temperature. In this study, we employed a phase field model to investigate the domain wall state of the SrTiO3/BaTiO3 superlattice structure. The domain wall thickness for the SrTiO3/BaTiO3 layer was measured using a hyperbolic function. Based on the simulation results, here, we show a domain wall state diagram to distinguish the hard and soft domain states. The polarization profiles across hard/soft domain walls were illustrated and analyzed. Our simulation results offer a useful concept for the control of the domain wall state in the ferroelectric superlattice.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-03T07:00:00Z
DOI: 10.1142/S2010135X22430032
- Structure and electrical properties of La2O3-doped
(K,Na,Li)(Nb,Ta)O3-(Bi,Na)TiO3 ceramics
Authors: Bingsen Wang, Junjun Wang, Jiaqi Li, Miao Yang, Minghao Huang, Tianyi Ma, Yu Tian, Fengmin Wu
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
In this paper, Lead-free based on 0.97(K[math]Na[math]Li[math])(Nb[math]Ta[math])O3–0.03Bi[math]Na[math]TiO3 with additives La2O3 (1, 2, 3, 4 wt.%) was prepared by the solid reaction method, and the effect of La dopant on the structural and electrical properties is investigated. The result indicates La dopant considerably decreases the optical band gap compared to the undoped composition. On the other hand, La doping leads to the higher dielectric property in a wider temperature, providing possibilities and directions for the subsequent development of ferroelectric photovoltaic materials with electrical properties and low optical band gap in a dramatical manner.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-04-03T07:00:00Z
DOI: 10.1142/S2010135X23500108
- Large piezoelectric anisotropy and high hydrostatic piezoelectric activity
due to an appreciable orientation effect and porosity in novel 2–2–0
composites
Authors: Vitaly Yu. Topolov, Andrey V. Krivoruchko, Natalia V. Prutsakova
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
The polarization orientation effect and porosity effect on the piezoelectric properties and related parameters are studied in 2–2-type composites based on domain-engineered relaxor-ferroelectric [011]-poled single crystals. The parameters, which are of great interest, are an anisotropy of the piezoelectric coefficients [math], an anisotropy of the energy-harvesting figures of merit [math] and the hydrostatic piezoelectric coefficient [math]. An orientation of the main crystallographic axes in each polydomain single-crystal layer is described by angles [math] and [math]. Diagrams built for the first time show the ([math]) regions, where a large anisotropy of [math] (or [math]) is achieved, and where inequality [math] 1000 pC/N holds. A large local max [math] = 1930 pC/N is achieved in a 2–2–0 PZN–0.065PT-based composite at the longitudinal piezoelectric coefficient [math] = 2290 pC/N and figure of merit [math] = 1.02[math]10[math] Pa[math]. The aforementioned large parameters are to be of value in piezoelectric sensing, energy harvesting and hydroacoustics.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-03-27T07:00:00Z
DOI: 10.1142/S2010135X23500066
- Effects of Mn-doping on the structure and electrical properties of
Sm-PMN-PT piezoceramics
Authors: Chaofeng Wu, Wen Gong, Jinfeng Geng, Jianye Cui, Lipeng Mi, Jingkai Nie, Qiang He, Jiajiu Li, Fang-Zhou Yao
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
MnO2-modified Pb[math]Sm[math](Mg[math]Nb[math])[math]Ti[math]O3 ceramics were prepared via a solid-state reaction approach. Results of detailed characterizations revealed that the addition of MnO2 has influence on the grain size, and all samples exhibit a pure perovskite structure. As the content of manganese increases, the volume of tetragonal phase increases. The ceramics with 1.5 mol.% MnO2 show a high electro-strain of 0.151% at 2 kV/mm. Therefore, this study provides a new insight into the role of MnO2 addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-03-16T07:00:00Z
DOI: 10.1142/S2010135X23500042
- High quality crystal growth and characterization of ferroelectric
Ba[math]Ca[math]TiO3 single crystal
Authors: Lei Liu, Fangyi Yin, Guiyuan Zhao, Limei Zheng, Xiuwei Fu, Zhitai Jia, Xutang Tao
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
B[math]Ca[math]TiO3 (BCT) single crystal has been widely studied as a promising lead-free ferroelectric material. In this work, high-quality BCT crystal was successfully grown by the Czochralski (CZ) method. The as-grown crystal is crack-free and shows black coloration. It possesses a high dielectric stability over a wide temperature range, while the dielectric loss is rather small below 90[math]C. Furthermore, it possesses excellent ferroelectric properties with residual polarization strength ([math]) and coercive field ([math][math]) of 17.93 [math]C/cm2 and 8.47 kV/cm, respectively. Besides, BCT crystal shows large electromechanical coupling factors, with [math][math], [math], [math] and [math] of 0.535, 0.254, 0.714 and 0.721, respectively. The piezoelectric coefficients [math], [math] and [math] are measured to be − 36.5, 130 and 246 pC/N, respectively.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-03-08T08:00:00Z
DOI: 10.1142/S2010135X23500054
- A comparative study on rigid and flexible magnetoelectric composites:
Review
Authors: Vaishnavi Khade, Madhuri Wuppulluri
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-03-04T08:00:00Z
DOI: 10.1142/S2010135X23400015
- Investigation of electrophysical, photo- and gas-sensitive properties of
ZnO-SnO2 sol–gel films
Authors: Irina A. Gulyaeva, Alexandra P. Ivanisheva, Maria G. Volkova, Victoria Yu. Storozhenko, Soslan A. Khubezhov, Ekaterina M. Bayan, Victor V. Petrov
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Thin nanocomposite films based on tin dioxide with a low content of zinc oxide (0.5–5 mol.%) were obtained by the sol–gel method. The synthesized films are 300–600 nm thick and contains pore sizes of 19–29 nm. The resulting ZnO–SnO2 films were comprehensively studied by atomic force and Kelvin probe force microscopy, X-ray diffraction, scanning electron microscopy, and high-resolution X-ray photoelectron spectroscopy spectra. The photoconductivity parameters on exposure to light with a wavelength of 470 nm were also studied. The study of the photosensitivity kinetics of ZnO–SnO2 films showed that the film with the Zn:Sn ratio equal to 0.5:99.5 has the minimum value of the charge carrier generation time constant. Measurements of the activation energy of the conductivity, potential barrier, and surface potential of ZnO–SnO2 films showed that these parameters have maxima at ZnO concentrations of 0.5 mol.% and 1 mol.%. Films with 1 mol.% ZnO exhibit high response values when exposed to 5–50 ppm of nitrogen dioxide at operating temperatures of 200[math]C and 250[math]C.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-02-23T08:00:00Z
DOI: 10.1142/S2010135X22450023
- Ferroelastic and 90[math] ferroelectric domains in Bi2WO6 single crystals
Authors: Xianghan Xu, Fei-Ting Huang, Sang-Wook Cheong
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
High-quality single crystals of Bi2WO6 are grown using a flux method. With different flux growth recipes, we aim to control the crystallization temperature to be lower and higher than the ferroelectric transition temperature, resulting in mono-domain and multi-domain Bi2WO6 crystals, respectively. Abundant ferroelastic orthorhombic twin domains are observed in the multi-domain crystals under an optical microscope. PFM studies unveil the 90[math] polarization change across those ferroelastic domain walls, as well as the absence of 180[math] ferroelectric domains in the as-grown multi-domain crystals, indicating a high energy cost of 180[math] ferroelectric domains. Moreover, a 45[math] tilt of the 90[math] ferroelectric domain walls is discovered, and this tilt creates a new type of charged 90[math] ferroelectric walls, which have not been observed in other bulk ferroelectrics.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-02-22T08:00:00Z
DOI: 10.1142/S2010135X22430020
- Microstructure regulation and failure mechanism study of BaTiO3-based
dielectrics for MLCC application
Authors: Yan Gu, Faqiang Zhang, Wanghua Wu, Zhifu Liu
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
Most widely used dielectrics for MLCC are based on BaTiO3 composition which inevitably shows performance degradation during the application due to the migration of oxygen vacancies ([math]). Here, the BaTiO3, (Ba[math]Ca[math])TiO3, Ba(Ti[math]Mg[math])O3, (Ba[math]Ca[math])(Ti[math]Mg[math])O3, (Ba[math]Ca[math]Dy[math])(Ti[math]Mg[math])O3 ceramics (denoted as BT, BCT, BTM, BCTM and BCDTM, respectively) were prepared by a solid-state reaction method. The core-shell structured grains ([math]200 nm) featured with 10-20 nm wide shell were observed and contributed to the relatively flat dielectric constant-temperature spectra of BTM, BCTM and BCDTM ceramics. The TSDC study found that the single/mix doping of Ca[math], especially the Mg[math], Mg[math]/Ca[math] and Mg[math]/Ca[math]/Dy[math] could limit the emergence of during the sintering and suppress its long-range migration under the electric-field. Because of this, the highly accelerated lifetimes of the ceramics were increased and the value of BCDTM is 377 times higher than that of BT ceramics. The [math] junction model was built to explain the correlation mechanism between the long-range migration of and the significantly increased leakage current of BT-based dielectrics in the late stage of HALT.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-01-21T08:00:00Z
DOI: 10.1142/S2010135X23500029
- Optimization design of autofocusing metasurface for ultrasound wave
application
Authors: Zhaoxi Li, Shenghui Yang, Mengqing Zhou, Chenxue Hou, Dongdong Chen, Chunlong Fei, Di Li, Yi Quan, Yintang Yang
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
In this paper, two optimized autofocusing metasurfaces (AFMs) with different desired focal distances are designed by using particle swarm optimization (PSO) algorithm. Based on the finite element simulation software COMSOL Multiphysics, the performance of ultrasound transducer (UT) with AFM at different design parameters in Airy distributions ([math]) and the bottom thickness ([math]) of AFM are simulated and analyzed. Based on the simulation data, the artificial neural network model is trained to describe the complex relationship between the design parameters of AFM and the performance parameters of UT. Then, the multiobjective optimization function for AFM is determined according to the desired performance parameters of UT, including focal position, lateral resolution, longitudinal resolution and absolute sound pressure. In order to obtain AFMs with the desired performance, PSO algorithm is adopted to optimize the design parameters of AFM according to the multiobjective optimization function, and two AFMs are optimized and fabricated. The experimental results well agree with the simulation and optimization results, and the optimized AFMs can achieve the desired performance. The fabricated AFM can be easily integrated with UT, which has great potential applications in wave field modulation underwater, acoustic tweezers, biomedical imaging, industrial nondestructive testing and neural regulation.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-01-18T08:00:00Z
DOI: 10.1142/S2010135X23500017
- Insulator-to-metal transition in RCoO3 (R = Pr, Nd)
Authors: Sujoy Saha, Sadhan Chanda, Alo Dutta, T. P. Sinha
Abstract: Journal of Advanced Dielectrics, Ahead of Print.
We report a straightforward tool to investigate insulator-metal transition in RCoO3 ([math] = Pr, and Nd) nanoparticles prepared by a sol–gel technique. Thermogravimetric analysis (TGA) of the as-prepared gel is performed to get the lowest possible calcination temperature of RCoO3 nanoparticles. The Rietveld refinement of the powder X-ray diffraction (XRD) patterns for both samples shows that the samples crystallize in the orthorhombic (Pnma) phase at room temperature. The particle size of the sample is determined by scanning electron microscopy. Ac conductivity of the materials is analyzed in the temperature range from 303 K to 673 K and in the frequency range from 42 Hz to 1.1 MHz. The insulator-to-metal transition of PrCoO3 and NdCoO3 is analyzed by ac impedance spectroscopy. DC resistivity measurement is also done to cross check the insulator-metal transition in RCoO3 system.
Citation: Journal of Advanced Dielectrics
PubDate: 2023-01-12T08:00:00Z
DOI: 10.1142/S2010135X23500030
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