Dielectric and ferroelectric materials Research Papers (original) (raw)

2025, 2012 IEEE International Conference on Condition Monitoring and Diagnosis

High voltage cable terminations are widely used in power system networks. A proper design of cable termination is essential in reducing the electric field distribution around the end of high voltage cable. However, if there are defects exist at cable termination structure, the electric field can be enhanced significantly and can be the source of electrical discharges. Therefore, it is important to understand the effect of defects on the electric field distribution at cable terminations. In this work, a 132 kV XLPE outdoor cable termination has been modelled using finite element analysis (FEA) method. The model has been used to simulate the electric field distribution in the cable termination in the presence of defects. Defects that have been considered are void defect in porcelain, stress cone and fluid, sharp pin on the porcelain surface and delamination defect between the insulator and the stress cone. The effect of different void location, material dielectric constant and porcelain radius on the electric field magnitude at cable termination have also been investigated. From the results obtained in this work, a better understanding of the electric field distribution at the cable termination with defects can be attained.

2025, Bulletin of the American Physical Society

at Riverside -Relaxor ferroelectric crystals (or simply relaxors) show high dielectric constants and low dielectric losses over a broad range of temperatures. There is consensus that the dielectric properties of the relaxors are due to the formation of polar nanoregions (PNR) below the Burns temperature. Each PNR possesses a net polarization that has many equivalent orientations. The gradient in the polarization leads to charge accumulation on the PNR surfaces. Such charge accumulation produces electric fields, which in turn affect the direction of the polarizations themselves. Knowledge of the electric field and of the polarization distributions is critical to understand the dielectric properties of these systems. Here, we present results on the calculated probability distribution of the electric fields and of the polarizations in the relaxors. Comparison to results obtained from neutron scattering experiments is provided.

2025, Bulletin of the American Physical Society

The American Physical Society Sorting Category: 11.1.1 (E)

2025, Bulletin of the American Physical Society

Submitted for the MAR06 Meeting of The American Physical Society Composition dependence of the diffuse scattering in relaxor (1x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (0 ≤ x ≤ 0.40) M. MATSUURA, K. HIROTA, ISSP The University of Tokyo, P. M. GEHRING, NIST Center for Neutron Research, ZUO-GUANG YE, W. CHEN, Department of Chemistry Simon Fraser University, G. SHIRANE, Deapartment of Physics Brookhaven National Laboratory -We have studied composition dependence of diffuse scattering in the relaxor sys 10, 20, 30, and 40% by neutron diffraction. The addition of ferroelectric PbTiO 3 (PT) modifies the "butterfly" and "ellipsoidal" diffuse scattering patterns observed in pure PMN (x = 0), which are associated with the presence of randomly oriented, polar nanoregions (PNR). The spatial correlation length ξ derived from the width of the diffuse scattering increases from 12.6 Å for PMN (x = 0) to 350 Å for PMN-20%PT, corresponding to an enlargement of the PNR. The integrated diffuse scattering intensity, which is proportional to χ ′′ , grows and reaches a maximum at x = 20%. Beyond x =30% PT, a concentration very close to the morphotropic phase boundary (MPB), no diffuse scattering is observed below T C , and well-defined critical behavior is observed. By contrast, the diffuse scattering for x ≤ 20% persists to low temperatures, where the system retains an average cubic structure (T C = 0). We can simulate the wave vector dependence of the diffuse scattering by assuming that it arises from the condensation of a soft transverse-optic (TO) phonon.

2025, arXiv (Cornell University)

Recently, a new orthorhombic phase has been discovered in the ferroelectric system (1x)Pb(Zn 1/3 Nb 2/3 )O3-xPbTiO3 (PZN-xPT) for x= 9%, and for x= 8% after the application of an electric field. In the present work, synchrotron x-ray measurements have been extended to higher concentrations, 10% ≤ x ≤15%. The orthorhombic phase was observed for x= 10%, but, surprisingly, for x ≥11% only a tetragonal phase was found down to 20 K. The orthorhombic phase thus exists only in a narrow concentration range with near vertical phase boundaries on both sides. This orthorhombic symmetry (MC-type) is in contrast to the monoclinic MA-type symmetry recently identified at low temperatures in the Pb(Zr1-xTix)O3 (PZT) system over a triangle-shaped region of the phase diagram in the range x= 0.46-0.52. To further characterize this relaxor-type system neutron inelastic scattering measurements have also been performed on a crystal of PZN-xPT with x= 15%. The anomalous soft-phonon behaviour ("waterfall" effect) previously observed for x= 0% and 8% is clearly observed for the 15% crystal, which indicates that the presence of polar nanoregions extends to large values of x.

2025, Bulletin of the American Physical Society

The American Physical Society

2025, Bulletin of the American Physical Society

We have performed inelastic neutron scattering studies of the low-energy phonon and spin-wave modes in the multiferroic BiFeO3. The low-energy phonon and spin wave dispersion relations along different directions have been mapped out over a broad temperature range from 100K to 750K. The temperature dependence of the intensities, dispersion relations, and lifetimes (inverse energy width) of these phonon and spin wave modes will be presented. Possible interactions between the lattice and spin dynamics will also be discussed. This work is supported by the Office of Basic Energy Sciences, DOE.

2025, Bulletin of the American Physical Society

2025, arXiv (Cornell University)

2025, Bulletin of the American Physical Society

Inelastic neutron scattering was used to measure both acoustic and optic phonons polarized along (110)(T2 mode) in the relaxor ferroelectric compound PZN-4.5 PT. In the low temperature rhombohedral phase, a single domain state was... more

2025, Proceedings of the National Academy of Sciences of the United States of America

PbZr 1-x Ti x O 3 (PZT) and Pb(Mg 1/3 Nb 2/3 ) 1-x Ti x O 3 (PMN-xPT) are complex lead-oxide perovskites that display exceptional piezoelectric properties for pseudorhombohedral compositions near a tetragonal phase boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are relaxors because the dielectric permittivity is frequency dependent and exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and correlates with a greater than 100% enhancement of the longitudinal piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing dielectric, structural, lattice dynamical, and piezoelectric measurements on PZT and PMN-xPT, two nearly identical compounds that represent weak and strong random electric field limits, we show that quenched (static) random fields establish the relaxor phase and identify the order parameter.

2025, Physical Review Letters

Complementary diffuse and inelastic synchrotron X-ray scattering measurements of lead zirconatetitanate (PZT) single crystals with composition near the morphotropic phase boundary (x=0.475) are reported. In the temperature range 293 K < T < 400 K a highly anisotropic quasielastic diffuse scattering is observed. Above 400 K this scattering disappears. Its main features can be reproduced by model of inhomogeneous lattice deformations caused by inclusions of a tetragonal phase into a rhombohedral or monoclinic phase. This observation supports the idea that PZT at its morphotropic phase boundary is essentially structurally inhomogeneous.

2025, Physical Review B

Room-temperature dispersion relations of the phonon modes associated with lead ion vibrations in ferroelectric PbTiO 3 single crystal have been investigated using inelastic neutron scattering. Both transverse acoustic and transverse optic modes propagating in the direction perpendicular to the spontaneous polarization show considerable splitting due to tetragonal anisotropy. The results of an earlier inelastic neutron scattering study are revised, and it is shown that the present picture is compatible with recent results obtained from Raman and Brillouin spectroscopy.

2024, IEEE Transactions on Dielectrics and Electrical Insulation

Recent work on ceramic-polymer composites for piezoelectric and pyroelectric applications is presented with special regard to the production and characterisation of new composite materials as well as two new applications of these composite materials. One of these composites is made using ceramic powders obtained using the sol-gel technique. This technique allows a better control of the stoichiometry as well as a lower temperature of crystallisation as compared with the conventional mixed oxides route. A better control of powder morphology also produces ceramic grains in the sub-micron range enabling the production of nanocomposites with electroactive properties. A second type of composite is reported using high temperature polymer PEEK, thus extending the temperature range of common electroactive composite materials. Finally the use of these materials is demonstrated in two piezoelectric applications, an angular acceleration accelerometer and an acoustic emission sensor.

2024, Journal of Advanced Dielectrics

In this paper, we will show the possibility of studying physical properties and irreversible phenomena that occur in blood by applying the dielectric Kluitenberg's nonequilibrium thermodynamic theory. Namely, we shall use some recent extensions of this theory that allow to infer its main characteristic parameters from experimental measures. Applying these results to the study of normal and diabetic blood we show, by comparing them, that it is possible to determine the difference, in some details, of the amount of particular phenomena occurring inside them and give a biological meaning to these phenomena. Moreover, observing a correspondence between a particular value of the frequency for which state coefficients are equal and glucose levels we introduce an alternative diagnostic method to measure the values of the glucose in the blood by determining only this frequency value. The thermodynamic description will be completed by determining the trend of the entropy production.

2024, Acta Crystallographica Section A Foundations and Advances

2024, Ceramics International

One of the most important lead-free piezoelectric compounds that has been studied extensively belongs to alkali niobate family, the sodium-potassium niobium (KNN) compound. In this study, KNN/PVDF composite was fabricated through hot compression molding of the components and its mechanical, thermal and electrical properties were studied. For this purpose, KNN was first synthesized by solid-state reaction during two-step calcination and its structural evolution was studied using XRD. Composite samples were prepared at different KNN to PVDF weight ratios. The powder mixture was then formed into disks by hot compression molding. The microstructure of the composite samples was investigated by SEM. The prepared samples were perfectly dense with a density in the range of 97.44% to 99.11% of the theoretical density. The thermal properties of the prepared composites were evaluated by thermogravimetric analysis and it was observed that final weight loss due to material degradation was reduced with increasing KNN weight percent. In addition, samples with higher KNN contents showed increased Young's modulus and yield strength values in compression. In order to investigate the electrical properties, the dielectric constant, diel9 11:38 ectric loss factor, piezoelectric charge and voltage coefficients and electric polarization were studied. The results showed that the dielectric constant increased with KNN content. The same trend was observed in the piezoelectric charge coefficient and the dielectric loss factor of the PVDF/KNN composites. At 80 wt% KNN, the composite showed a distinct ferroelectric behavior with a remanent polarization of 0.255 μC/cm 2 and 20.5 kV/cm coercivity. According to the results of the present study, hot compression molding is an effective method for producing KNN/PVDF composites with improved mechanical and thermal properties compared to its constituents.

2024, Journal of Advanced Dielectrics

The BNT ceramic sample might be a good replacement for PZT piezoelectric in industrial applications, especially in energy harvesting from crystal vibrations. In order to enhance the performance of BNT ceramic, the solid solution was chosen by substitution with Ba þ2 at Morphtropic Phase Boundary (MPB). The BNT-xBT powders with x ¼ 1, 0.07, 0.06 and 0 were prepared by the hydrothermal method with average particle size (65-150 nm) at (90 C/72 h). The ceramic disc was sintered at (1150 C/4 h) and showed excellent relative density of about 96%. The results of X-ray diffraction (XRD) confirmed the MPB for x ¼ 0:06 and 0.07, while the BNT had a rhombohedral structure and BT had a tetragonal structure. The dielectric measurements showed that BNT, BNT-7BT, BNT-6BT behave as the relaxator ferroelectric and showed a strong dependence on frequency, especially in the MPB region while BT behaves as a normal ferroelectric. Both the Curie temperature and depolarization temperature decrease at the MPB region and showed strong dependency on frequency.

2023, Acta Crystallographica Section A Foundations and Advances

Lacunar spinel is a class of compounds that are derivative of the spinel family, AB2X4, with some vacancies at the A-site. They are very interesting both crystallographically and with respect to the physical properties as several members exhibit structural phase transition from F-43m to R3m and long-range magnetic ordering at low-temperature.[1,2] Having R3m (C3v symmetry) space group along with long-range magnetism make these compounds interesting in the aspect of spintronics, as they may host Néel-type skyrmions.[3] One such very well-studied compound is GaV4S8 that hosts skyrmion with individual size of 22 nm. [3] Here, we report a study on a different member of the lacunar spinel family, GaMo4Se8 that is expected to have smaller skyrmions size. We performed high-resolution powder neutron diffraction across the structural phase transition (TS = 51 K). Through Rietveld refinement, it is found out that there are two coexisting low-temperature crystal structures with space group R3m (major phase) and Imm2 (minor phase) (Fig.1), which is very unique only for GaMo4Se8.[4] We propose an explanation for the coexisting of both crystal structures through mode-crystallographic and bond-valence sum analysis and postulate that the large strain in the rhombohedral structure is alleviated by the formation of the orthorhombic phase with larger displacive distortion amplitude. Furthermore, we have carried out magnetization measurements and performed magnetic critical behavior analysis. We find that the magnetic transition in GaMo4Se8 is close to a tricritical mean-field model, and the analysis of the magnetic phase diagram using magneto-entropic map revealed a positive phasefield which might be an indication of the presence of complex magnetic structures such as cycloid or skyrmions states. Figure 1. The percentage change in cubic (F-43m), rhombohedral (R3m), and orthorhombic (Imm2) phases of GaMo4Se8 as a function of temperature. The Mo4 tetrahedron (green color) corresponding to each phase is shown along with the possible distortion direction (red color arrow).

2023, Ceramics International

Nd 5.5 WO 11.25-δ , (Nd 5/6 La 1/6) 5.5 WO 11.25-δ and Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ mixed oxides have been prepared using mechanochemical activation (MA) of Nd 2 O 3-WO 3 , Nd 2 O 3-La 2 O 3-WO 3 , Nd 2 O 3-MoO 3-WO 3 mixtures in a highpower planetary ball mill. Genesis of these tungstates structural properties was studied by XRD, SEM, TEM with EDX analysis, 1 H NMR, IR and Raman spectroscopy. X-ray diffraction has revealed that MA results in formation of a pure fluorite structure already after milling. High-density ceramic pellets have been obtained after sintering at 1350°C. Transport properties of Nd 5.5 WO 11.25-δ mixed oxide were improved by the partial substitution of Nd with La in (Nd 5/6 La 1/6) 5.5 WO 11.25-δ and W with Mo in Nd 5.5 W 0.5 Mo 0.5 O 11.25-δ samples. For all samples the electrical conductivity values measured in a humid atmosphere (up to~10 −3 S/cm at 550°C) exceed those measured in a dry atmosphere indicating the proton character of conductivity.

2023, Journal of Materials Science Letters

Ceramic-polymer composites are useful for a variety of applications. Composite piezoelectrics are particularly interesting as transducers for future medical devices and as capacitor material. Piezoelectric ceramics offer a number of advantages [1] as a transducer material, but their usefulness is limited by their high acoustic impedance (Z ~ 30 x l 0 6 kgm 2 sec-l) and very high dielectric constant [1-4]. Piezoelectric polymers (e.g. polyvinylidene fluoride; PVDF) do not have

2023, Bulletin of the American Physical Society

Tennessee-Recently there have been significant advances in the efficiencies of traditional thermoelectric compounds gained via the creation of thermoelectric nanocomposites possessing substantially reduced thermal conductivity relative to their bulk counterparts [1,2]. The dramatic reduction in the heat transport of these nanocomposites is often attributed to the increased interface scattering of phonons or induced surface/boundary modes; however notably little work has been put worth into exploring the detailed changes in the phonon density of states in many of these functional nanocomposite samples. Here we present inelastic neutron scattering measurements exploring the phonon density of states in a series of Si1-xGex thermoelectric nanocomposites. The evolution of the phonon spectral weight distribution and linewidths as a function of Ge-doping will be discussed and compared to the known bulk phonon density of states in this system.

2023, Physical Review B

We present a quantitative analysis of the phonon lineshapes obtained by neutron inelastic scattering methods in the relaxor ferroelectric Pb(Mg 1/3 Nb 2/3)O3 (PMN). Differences in the shapes and apparent positions of the transverse acoustic (TA) and transverse optic (TO) phonon peaks measured in the (300) and (200) Brillouin zones at 690 K are well described by a simple model that couples the TA and soft TO modes in which the primary parameter is the wave vector and temperature-dependent TO linewidth Γ(q, T). This mode-coupling picture provides a natural explanation for the uniform displacements of the polar nanoregions, discovered by Hirota et al., as the PNR result from the condensation of a soft TO mode that also contains a large acoustic component.

2023, Journal of Advanced Dielectrics

A brief review is presented that summarizes recent neutron diffuse scattering measurements on single crystal PbMg1/3Nb2/3O3 (PMN) and PbZn1/3Nb2/3O3 (PZN) doped with PbTiO3 (PT). Emphasis is placed on results that suggest that the short-range, polar correlations observed in these systems are connected to the anomalous relaxor dielectric properties, and in particular to the large values of the piezoelectric coefficient d33 near the morphotropic phase boundary.

2023, Phase Transitions

X-ray and neutron scattering studies of the lead-based family of perovskite relaxors PZN-xPT and PMN-xPT have documented a highly unusual situation in which the near-surface region of a single crystal can exhibit a structure that is different from that of the bulk when cooled to low temperatures. The near-surface region, or "skin" can also display critical behavior that is absent in the crystal interior, as well as a significantly different lattice spacing. By varying the incident photon energy, and thus the effective penetration depth, x-ray measurements indicate a skin thickness of order 10 µm to 50 µm for PZN-xPT samples with 0 ≤ x ≤ 8%. Neutron residual stress measurements on a large PMN single crystal reveal a uniform lattice spacing within the bulk, but an increased strain near the surface. The presence of this skin effect has led to incorrect phase diagrams for both the PZN-xPT and PMN-xPT systems and erroneous characterizations of the nature of the relaxor state.

2023, Applied Physics Letters

We report neutron diffuse scattering measurements on a single crystal of 68%Pb(Mg1∕3Nb2∕3)O3-32%PbTiO3. Strong diffuse scattering is observed at low temperatures. An external field applied along the [001] direction affects the diffuse scattering in the (HK0) plane significantly, suggesting a redistribution occurs between polar nanoregions of different polarizations perpendicular to the field. By contrast, the [001] field has no effect on the diffuse scattering in the (H0L) and (0KL) zones.

2023, Composites Science and Technology

Solvent cast and compression molded composite films based on poly(vinylidene fluoride-trifluoroethylene), containing pristine and silylated BaTiO 3 particles, were poled, and their electromechanical response (d 33), their dielectric properties, and the crystalline structure of the embedded BaTiO 3 particles, probed by X-ray diffraction, were recorded during one week. Their d 33 was also measured after long-term aging (>3years). During this time the d 33 decreased for all composites. The d 33 of solvent cast

2023

M. Paściaka,∗ T. R. Welberryb, J. Kuldac, S. Leonid, and J. Hlinkaa† a Institute of Physics of the Czech Academy of Sciences Na Slovance 2, 182 21 Prague 8, Czech Republic bResearch School of Chemistry, Australian National University, Canberra ACT 0200, Australia cInstitut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France dCardiff University, School of Chemistry, Park Place, CF10 3AT, Cardiff, UK

2023, Journal of Advanced Dielectrics

A study of dielectric properties of composite films on the base of poly(vinylidene fluoride-trifluoroethylene) copolymer P(VDF-TrFE) and ferroelectric ceramics of barium lead zirconate titanate (BPZT) solid solution is presented in this work. The composite films containing up to 50 vol.% of BPZT grains with size [Formula: see text]1[Formula: see text][Formula: see text]m were prepared by the solvent cast method. Frequency dependences of real and imaginary components of the complex permittivity were determined. The concentration dependence of the dielectric constant was discussed.

2023, Solid State Ionics

The effect of dielectric constant of the PbTiO 3 dispersoid on the conductivity of Na 2 SO 4 has been probed. At the Curie temperature, 490°C, PbTiO 3 undergoes ferroelectric to paraelectric phase transition followed by a sharp change in the dielectric constant. The Na 2 SO 4-PbTiO 3 composites have been prepared at two different temperatures, namely 600 and 900°C. Compositions containing 5, 10, 20, 30, 40, 50 m% PbTiO 3 have been investigated using Impedance Spectroscopy, Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and Rietveld analysis. The series of compositions prepared at 900°C exhibit a maxima in the conductivity for 20 m% PbTiO 3. The composites prepared at 600°C exhibit a peak in the conductivity at 20 m% PbTiO 3 in addition to the percolation threshold at 40 m% PbTiO 3. The enhancement in the conductivity by a factor of 40 at 300°C has been observed for the system prepared at 600°C while an enhancement in the conductivity by a factor of 8 at 300°C has been observed for the system prepared at 900°C. Further, the transition temperature of Na 2 SO 4 remains unaltered for both series. A slight nonlinearity has been observed in the vicinity of the transition temperature of the dispersoid.

2023, Journal of Advanced Dielectrics

The current paper presents results of dielectric response, pyroelectric behavior and conductivity study of lead-free ferroelectric barium orthovanadate ( Ba 3( VO 4)2 or Ba 3 V 2 O 8) ceramic, for a wide range of temperature and frequency. An X-ray diffraction study suggests the formation of a single-phase compound in trigonal crystal system. The SEM micrograph of gold-coated pellet sample shows well-defined and homogeneous morphology. Detailed studies of dielectric parameters (εr and tan δ) of the compound as a function of temperature and frequency reveal their independence over a wide range of temperature and frequency. The nature of Polarization versus electric field (P–E) hysteresis loop of Ba 3 V 2 O 8 at room temperature suggests its ferroelectric nature. The temperature dependence of pyroelectric coefficient and figure of merits of the sample support its dielectric response. The nature of variation of dc conductivity with temperature confirms the Arrhenius and negative temper...

2023, Physica B: Condensed Matter

Submitted for the MAR06 Meeting of The American Physical Society Composition dependence of the diffuse scattering in relaxor (1x)Pb(Mg 1/3 Nb 2/3)O 3-xPbTiO 3 (0 ≤ x ≤ 0.40) M.

2023, Journal of Advanced Dielectrics

2023, Ceramics International

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2023, RSC Advances

Strontium hafnium oxide (SrHfO3) has great potential as a high-k gate dielectric material, for use in memories, capacitors, CMOS and MOSFETs.

2023, MRS Proceedings

ABSTRACTPbZr0.53Ti0.4703 doped with 0.6% at. of Gd2O3 has been produced following the traditional solid state reaction technique. The ferro-paraelectric transition temperature is reduced from 386 °C to 352 °C. Remnant polarization and coercive field measurements were made from the hysteresis loops obtained at 23 °C and at different applied electric fields up to a maximum of 17 kV/cm. Piezoelectric performance was studied in the 4 Hz to 4 MHz frequency range at 25 °C and the radial electromechanical coupling factor was determined. A detailed electrical conductivity study in the 30-450 °C temperature range is performed in a wide frequency interval. The different participating transport mechanisms are elucidated and the corresponding activation energies were determined by fitting the experimental data. In particular, in the 30 to 300 °C temperature interval, the ac conductivity follows Jonscher universal relaxation law.

2023, Journal of Advanced Dielectrics

2023, Physica B: Condensed Matter

The copper substituted tungsten bronze ceramics with generic formulaBa 5 CaCu X Ti 2x Nb 8 O 30 (x=0.0, 0.02, 0.04, 0.06 and 0.08) were successfully synthesized for the first time by solid state reaction method. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were utilized to examine the different structural parameters and elemental compositions. XRD study depicted the single phase tetragonal structure having space group P4bm. The crystallite size was observed to be in the range 14.4-30.23 nm. The coexistent of ferroelectricity and magnetism was established by P-E and M-H measurements. The P-E loop study indicated an increase in the coercive field (11.805-23.736 kVcm-1) while the M-H study depicted adecrease in the magnetization (7.65 x10-4-7.65 x10-4 emu/g) with the incorporation of Cu 2+ ions. Raman spectrum depicted that there is shift in the position of Raman modes with the substitution of copper which revealed one-mode behavior in the synthesized ceramics.

2023

We have synthesized Sr and La substituted Pb (1-x-3y/2) Sr x La y (Zr z , Ti (1−z))O 3 ceramics with x=0.06, y=0.01, 0.03, 0.05, z=0.56 by solid-oxide route. Compacted discs were sintered at optimized temperature of 1280°C for 2 h and its phase formation was confirmed by XRD analysis. Rietveld refinement confirmed that for the composition with y=0.03 coexistence of tetragonal and rhombohedral phases comparatively closer to MPB. Dielectric and ferroelectric properties of discs were investigated thoroughly as a function of La content. Among the three compositions, ceramics with y=0.03 (PSLZT) exhibit higher piezoelectric voltage coefficient (g 33) of 30 mV.m/N which is relatively high compared to commercial PZT compositions. This composition was further utilized to fabricate free-standing piezoelectric thick films of 100 μm thickness using tape casting method with optimized slurry formulation. Warpage free PZT thick films with Pt electrodes were achieved with better density by co-sintering at 1060°C for 2 h. Free standing thick films were characterized for their structural, microstructural, ferroelectric and piezoelectric properties and compared with bulk ceramic properties. The relative dielectric constant of 1250 with loss tangent of 0.02-0.03, remnant polarization of about 19 μC cm −2 , piezoelectric charge coefficient of 300-325 pC/N and piezoelectric voltage coefficient up to 27 mV.m/N have been observed. These results indicate piezoelectric voltage coefficient of PSLZT free standing thick films is comparable to that of its bulk ceramic counterpart.

2023, International Journal of Advances in Scientific Research

PZT-PVDF composites were prepared using different particle size of PZT and a hot press apparatus has been used for making samples. The structural and compositional analysis of the composite sample was done by using Scanning Electron Microscope (SEM) and Energy Dispersive Analysis of X-rays (EDAX) respectively. The grain size of the ball milled PZT powder was analyzed using powder X-Ray Diffraction (XRD). The samples were poled at a fixed temperature for about an hour under different poling fields. The dielectric constant (?r) and the piezoelectric properties like piezoelectric strain coefficient (d33) and voltage coefficient (g33) of composite have been analyzed.

2023, Journal of Materials Science Research

The effects of Dy 2 O 3 on the phase composition, microstructure, and the dielectric property, especially, dielectric constant, of AlN ceramics sintered at low-temperature (1650 o C), were investigated systematically. X-ray diffraction (XRD) was employed to indentify the phase compositions of the ceramics during the sintering. Scanning electronic microscopy (SEM) was used to observe the microstructures of the AlN ceramics. The results show that the dielectric constant changes with the amount of Dy 2 O 3. When the amount of Dy 2 O 3 is less than 0.93 wt.%, the dielectric constant increases with the increased amount of Dy 2 O 3. The dielectric constant of the AlN ceramics is higher than 200 when the amount of Dy 2 O 3 is 0.93 wt.%. However, when the amount of Dy 2 O 3 is more than 0.93 wt.%, the dielectric constant decreases with the increased amount of Dy 2 O 3. The dielectric constant of the AlN ceramics with 1.87 wt.% Dy 2 O 3 is only about 15, which closed to the theoretical value of pure AlN ceramics. The analysis illuminated that the grain phases changed from Al 2 O 3-rich aluminate to AlDyO 3 which existed at triple pockets with the increased amount of Dy 2 O 3 , the former can improve the dielectric constant greatly due to ion relaxation polarization.

2022, Journal of Physics and Its Applications

In order to enhance insight of layered structure, we perform numerical calculation to obtain the dynamic electric susceptibility in bi-layers ferroelectrics. Since susceptibility is a parameter which gives response to the external field, then determination of this parameter is important. A lattice model is employed to slice bilayer structure into several lattices. Then, Landau-Khalatnikov equation of motion is used in each lattice to construct a matrix equation of equation of motion. The solution is obtained by applying entire-cell effective medium. We find that the homogeneity of dynamic polarization is different from homogeneity of the single individual layer due to the existence of interlayer interaction. As a result, the electric susceptibility is also altered. It is also noticed that there is a relation between the homogeneity of dynamic polarization and the value of electric susceptibility near resonant frequency. The higher the homogeneity, the bigger the values of susc...

2022, Materials Research Bulletin

2022, Scientific Reports

In ferroelectrics, manifestation of a strong electromechanical coupling is attributed to both engineered domain morphology and phase transformations. However, realization of large sustainable and reversible strains and polarization rotation has been limited by fatigue, nonlinearity and hysteresis losses. Here, we demonstrate that large strain and polarization rotation can be generated for over 40 × 10 6 cycles with little fatigue by realization of a reversible ferroelectric-ferroelectric phase transition in [011] cut Pb(In 1/2 Nb 1/2)O 3-Pb(Mg 1/3 Nb 2/3)O 3-PbTiO 3 (PIN-PMN-PT) relaxor ferroelectric single crystal. Direct tuning of this effect through combination of stress and applied electric field, confirmed both macroscopically and microscopically with x-ray and Raman scattering, reveals the local symmetry while sweeping through the transition with a low applied electric field (<0.2 MV/m) under mechanical stress. The observed change in local symmetry as determined by x-ray scattering confirms a proposed polarization rotation mechanism corresponding to a transition between rhombohedral and orthorhombic phases. These results shed more light onto the nature of this reversible transformation between two ferroelectric phases and advance towards the development of a wide range of ferroic and multiferroic devices.