Diffuse Phase Transition Research Articles

Deep insights into the Cu- and W-doped Na0.5Bi0.5TiO3 solid solution: A study focusing on optical, dielectric and electrical properties

Na0.5Bi0.5TiO3 ceramic is among the most promising dielectric materials for several advanced electronic devices due its exceptional features. However, its high oxygen ionic conductivity and wide band-gap energy limit its use for commercial applications. Here, a new Lead-free solid solution 0.995(Na0.5Bi0.5TiO3)-0.005(BiCu0.75W0.25O3), abbreviated 0.995NBT-0.005BCW, was investigated to enhance the electrical and optical performance of NBT ceramic. 0.995NBT-0.005BCW was successfully elaborated by the solid-state technique. The structural, optical, dielectric and electric properties were investigated systematically. The incorporation of BCW into NBT improved the long-range order of the structure, facilitated the poling process, enhanced the electrical properties of the pure NBT and led to the local lattice distortion, generating new electronic levels inside the NBT bandgap. The calculated band gap value ∼3 eV suggests its suitability in power electronic devices. The variation of dielectric constant and dielectric loss with temperature (370–800 K) at different frequencies (100–106 Hz) showed diffused phase transition. The study of dc-conductivity suggests that the substitution of Cu2+ for Ti4+ would formCuTi″, which transforms Cu2+ to Cu+. Our compound is a novel material with interesting properties and offers exciting possibilities for engineering and manufacturing applications.

Rigidity of dipolar coupled H2O molecular network in external electric field

We have performed the first study of the effect of an external electric field on the quantum paraelectric state of the electric dipolar lattice of polar water molecules confined within nano-sized cages of beryl crystal lattice. The complex dielectric permittivity ε* = ε'+iε" of a water subsystem in hydrous beryl is measured at frequencies 1 Hz-1 MHz in the temperature interval 10–300 K both in zero and 7 kV/cm external field. For comparison, we measure dielectric response of conventional quantum paraelectric KTaO3. In KTaO3, the application of electric field of several kV/cm suppresses quantum fluctuations and leads to a shallow maximum of ε′(T) around 15 K that could indicate a diffuse phase transition. In hydrous beryl, however, a bias electric field of up to 7 kV/cm has no effect on the dielectric response of the water molecules network. This result is confirmed by Monte Carlo simulations. We attribute the enhanced rigidity of the water dipolar subsystem to the strong long-range dipole-dipole interaction between separate H2O molecules. The field that could affect the polarization state of the dipoles is estimated to be of the order of 100 kV/cm.

Effect of the DC-bias electric field on the phase transition characteristics in PMN ceramics

Relaxor ferroelectrics play an important role for technological applications, mainly for using in the fabrication of actuators, transducers and sensors. Therefore, there has been an increasing interest of the scientific community in the investigation of the physical properties of such system in order to better elucidate the observed intriguing and unsolved phenomena. In this work, relaxor Pb(Mg1/3Nb2/3)O3 (PMN) ceramic system was prepared and the dielectric properties have been studied in details as a function of frequency, temperature and magnitude of the DC-bias electric field. Results reveal that the temperature dependence of the dielectric permittivity can be successfully described in the whole analyzed temperature range (100–400 K) by using a macroscopic statistical model, which describe the dielectric response in relaxor systems with diffuse phase transition (DPT). By using this phenomenological model, the temperature and DC-bias electric field dependences of the dielectric permittivity have been also revisited, from the analysis of the DPT behavior, promoting a careful discussion on the nature of the phase transition in relaxors materials. The calculated sizes of the polar nanoregions (PNRs) suggest the development of a structural disorder in the studied system, which promote the high diffuse ferroelectric transition as the amplitude of the DC-bias electric field increases.

Excellent strain properties in (K,Na)NbO3-based piezoceramics induced by lamination composite strategy

To reconcile the contradiction between piezoelectric property and its temperature stability, the preparation of composite piezoceramics using multiple components has become an emerging direction. Herein, (K,Na)NbO3-based piezoceramics are adopted to prepare high-performance laminated composite ceramics inspired by the lamination composite strategy, and sintered in the reducing atmosphere to meet the development of multilayer piezoelectric actuators with base metal internal electrodes. By adjusting the composition ratio, a high inverse piezoelectric coefficient d33* of 1065 pm/V (@ 2 kV/mm) is obtained in the two-component composite ceramics, which fluctuated less than ± 6% in the range of 25–160 °C. In the three-component composite ceramics, a higher d33* value of 1326 pm/V (@ 2 kV/mm) is achieved and maintained > 90% until 150 °C. The electric-field-induced strain performances of laminated composite ceramics significantly exceed those of their basic components, which is related to the piezoresponse gain provided by the internal interfaces. The excellent temperature stabilities come from the more diffused phase transition temperature range formed by the complementation of multiple components. The combination of ultrahigh strain performance, high temperature stability, and good fatigue resistance, together with sintering in the reducing atmosphere, constitutes an important step to promote the application of (K,Na)NbO3-based multilayer piezoelectric actuators.

Enhanced Energy Storage Performance and Efficiency in Bi0.5(Na0.8K0.2)0.5TiO3-Bi0.2Sr0.7TiO3 Relaxor Ferroelectric Ceramics via Domain Engineering.

Dielectric materials are highly desired for pulsed power capacitors due to their ultra-fast charge-discharge rate and excellent fatigue behavior. Nevertheless, the low energy storage density caused by the low breakdown strength has been the main challenge for practical applications. Herein, we report the electric energy storage properties of (1 - x) Bi0.5(Na0.8K0.2)0.5TiO3-xBi0.2Sr0.7TiO3 (BNKT-BST; x = 0.15-0.50) relaxor ferroelectric ceramics that are enhanced via a domain engineering method. A rhombohedral-tetragonal phase, the formation of highly dynamic PNRs, and a dense microstructure are confirmed from XRD, Raman vibrational spectra, and microscopic investigations. The relative dielectric permittivity (2664 at 1 kHz) and loss factor (0.058) were gradually improved with BST (x = 0.45). The incorporation of BST into BNKT can disturb the long-range ferroelectric order, lowering the dielectric maximum temperature Tm and inducing the formation of highly dynamic polar nano-regions. In addition, the Tm shifts toward a high temperature with frequency and a diffuse phase transition, indicating relaxor ferroelectric characteristics of BNKT-BST ceramics, which is confirmed by the modified Curie-Weiss law. The rhombohedral-tetragonal phase, fine grain size, and lowered Tm with relaxor properties synergistically contribute to a high Pmax and low Pr, improving the breakdown strength with BST and resulting in a high recoverable energy density Wrec of 0.81 J/cm3 and a high energy efficiency η of 86.95% at 90 kV/cm for x = 0.45.

Effect of Disorder in the Structure of a Ferroelectric Composite Material xPbSe·(1 – x)PbSeO3 on the Smearing of the Phase Transition

This paper analyzes the experimental and theoretical studies of the problem of a diffuse phase transition (PTC) in a composite material xPbSe⋅(1 – x)PbSeO3, in which x varies from 0 to 1. The decrease in stability in the virtual cubic phase of lead selenide (PbSe) is achieved by oxidizing it with atmospheric oxygen and forming a ferroelectric disordered monoclinic phase of lead selenite (PbSeO3). The mechanism of lead selenide oxidation by air oxygen is studied by X-ray diffractometry, optical reflection in the infrared region of the spectrum, X-ray emission analysis (the chemical shift method), nuclear magnetic resonance, studies of AC and DC conductivity, differential scanning calorimetry, and other methods. The reason for the smearing of the phase transition in the xPbSe⋅(1 – x)PbSeO3 composite, in which x varies from 0 to 1, is analyzed based on the previously obtained experimental results of its detection.

Microscopic origin and relevant grain size effect of discontinuous grain growth in BaTiO3-based ferroelectric ceramics

Barium titanate [BaTiO3 (BT)]-based ceramics are typical ferroelectric materials. Here, the discontinuous grain growth (DGG) and relevant grain size effect are deeply studied. An obvious DGG phenomenon is observed in a paradigmatic Zr4+-doped BT-based ceramic, with grains growing from ∼2.2–6.6 to ∼121.8–198.4 μm discontinuously near 1320 ℃. It is found that fine grains can get together and grow into large ones with liquid phase surrounding them above eutectic temperature. Then the grain boundary density (Dg) is quantitatively studied and shows a first-order reciprocal relationship with grain size, and the grain size effect is dependent on Dg. Fine grains lead to high Dg, and then cause fine domains and pseudocubic-like phase structure because of the interrupted long-range ferroelectric orders by grain boundary. High Dg also causes the diffusion phase transition and low Curie dielectric peak due to the distribution of phase transition temperature induced by internal stress. Local domain switching experiments reveal that the polarization orientation is more difficult near the grain boundary, implying that the grain boundary inhibition dominates the process of polarization orientation in fine-grain ceramics, which leads to low polarization but a high coercive field. However, large-grain ceramics exhibit easy domain switching and high & similar ferroelectricity. This work reveals that the grain boundary effect dominates the grain size effect in fine-grain ceramics, and expands current knowledge on DGG and grain size effect in polycrystalline materials.

Investigation of local structure and phase transformation in Ce-doped barium titanate and correlation with electrical properties

ABSTRACT BaTiO3-based materials are used as the replacement for lead-based perovskite materials for its wide dielectric applications. But the substitution of different doping elements in pure BaTiO3 drastically affects the microstructure, phase transition behavior and electrical properties. In the present work, local structure, phase transformation and dielectric behavior of BaCexTi1-xO3 (BCT) ceramics were studied for compositions x = 0.02, 0.05 and 0.1. A diffuse phase transition from orthorhombic to cubic via tetragonal in BCT with increasing Ce content was observed. An increase in particle size with Ce doping concentration was observed in FESEM images. Spherical and cuboid-shaped particle in the order of 80–150 nm was observed in transmission electron microscopic (TEM) images. RAMAN spectra confirm the tetragonal to cubic phase transition. Local structural and phase transformation behavior was obtained from laboratory-based PDF and XRD, respectively. Change in PDF was observed due to an increase in Ce doping. Dielectric properties decreased for Ce mole fraction of x = 0.1.

Ultrahigh thermal stability of dielectric permittivity in 0.6Bi(Mg1/2Ti1/2)O3–0.4Ba0.8Ca0.2(Ti0.875Nb0.125)O3

0.6Bi(Mg1/2Ti1/2)O3–0.4Ba0.8Ca0.2(Nb0.125Ti0.875)O3 ceramics with a pseudo-cubic structure and re-entrant dipole glass behavior have been investigated via x-ray diffraction and dielectric permittivity–temperature spectra. It shows excellent dielectric–temperature stability with small variations of dielectric permittivity (±5%, 420–802 K) and dielectric loss tangent (tanδ < 2.5%, 441–647 K) in a wide temperature range. Three dielectric anomalies are observed from 290 to 1050 K. The low-temperature, weakly coupled re-entrant relaxor behavior was described using the Vogel–Fulcher law and the new glass model. The mid- and high-temperature dielectric anomalies are characterized by isothermal impedance and electrical modulus. The activation energy of both dielectric relaxation and conductivity follows the Arrhenius law in the temperature ranges of 633–753 and 833–973 K, respectively. The ultrahigh thermal stability of dielectric permittivity is attributed to the weak coupling of polar clusters, the formation of diffuse phase transition, and the local phase transition of calcium-containing perovskite. The results provide new insights into the defects behavior and the modification way of re-entrant relaxor behavior.

Development of high-temperature stable dielectric material

Temperature stability is one of the important parameters for the capacitor to work in various temperature ranges. BaTiO3-based materials are one of the popular choices as X7R, X8R, X9R, and X8T (class II) materials in capacitors due to the high value and temperature stability of their dielectric permittivity. Several studies have revealed that the property and performance of these materials can be tailored by doping different elements at A and B sites. In this work, Ba(1-x) Srx Zr 0.1Ti0.9O3 + 2 wt% MgO (x = 0,0.02,0.04) was synthesized via the solid-state reaction method. Liquid phase sintering was adopted to assist in the formation of dense microstructures. For this purpose, MgO was used as a sintering aid. We studied the structural, morphological, dielectric, and energy storage properties of these composites. The powder X-ray diffraction pattern confirmed the formation of cubic phase in Ba(1-x) Srx Zr0.1Ti0.9O3. FESEM micrograph of these compositions revealed that the sample had been properly sintered and possesses a dense microstructure. In dielectric measurement, the εr -T and tanδ -T curves have been plotted for different compositions at different frequencies. The result showed stable dielectric properties with the variation of temperature in all composites, which is characteristic of temperature-stable dielectric materials. For all the compositions, it has been found that there is a decrease in dielectric constant with the frequency, which is due to a decrease in polarisations of the atoms or molecules with the increase in frequency. The flatness of the dielectric curve confirms that the studied material is highly preferable for Class II dielectric-type capacitors. The broadening of the dielectric peak is observed for all the compositions because of the diffusive phase transition. The variation of capacitance or ∊r in terms of TCC is –33 to +22% for a wide range of temperatures from −55 °C to +150 °C.

Effect of Sr-doping on structural, morphological and dielectric properties of BaTi0.93Sn0.07O3 ferroelectric ceramics

In this report, we studied the Ba1-xSrxTi0.93Sn0.07O3 (x = 0.00, 0.10, 0.20, and 0.30) Perovskite ceramics produced by solid-state reaction (SSR) method and investigated their structural, morphological and dielectric properties by XRD, SEM, and LCR meter respectively. The Rietveld refinement of the XRD pattern confirms the samples crystallize in the Perovskite structure and transform from tetragonal for x = 0.0 to the co-existence of both cubic (Pm-3m) and tetragonal (P4mm) phases near room temperature for x ≥ 0.10. The Williamson-Hall (W–H) method has been used to determine the crystallite size and microstrains from the XRD peaks analysis, which showed the crystallite size value decreases with increased doping with Sr. The surface morphology shows the formation of ceramic grains with well-defined grain boundaries, as well as a decrease in grain size with an increase in the doping ratio. Moreover, the elemental ratio of doped ions was confirmed by EDS. The dielectric properties (έ, and tanδ) were studied as a function of temperature (20–150 °C) and a frequency (20 kHz - 3 MHz). The values of the dielectric constant έ decrease with the higher the frequency used. A diffuse phase transition was observed when doped with Sr. Where doping with Sr causes outstanding stability of έ values, which is evident by the flattening the dielectric constant curve, addition to increasing the dielectric constant values over range studied temperatures.

Mitigation of Thermal Instability for Electrical Properties in CaZrO3-Modified (Na, K, Li) NbO3 Lead-Free Piezoceramics.

Lead-free ceramics 0.96(Na0.52K0.48)0.95Li0.05NbO3-0.04CaZrO3 (NKLN-CZ) are prepared by using the solid-state procedure and two-step synthesis technique. The crystal structure and thermal stability of NKLN-CZ ceramics sintered at 1140-1180 °C are investigated. All the NKLN-CZ ceramics are ABO3-type perovskite phases without impure phases. With the increase in sintering temperature, a phase transition occurs in NKLN-CZ ceramics from the orthorhombic (O) phase to the concomitance of O-tetragonal (T) phases. Meanwhile, ceramics become dense because of the presence of liquid phases. In the vicinity of ambient temperature, an O-T phase boundary is obtained above 1160 °C, which triggers the improvement of electrical properties for the samples. The NKLN-CZ ceramics sintered at 1180 °C exhibit optimum electrical performances (d33 = 180 pC/N, kp = 0.31, dS/dE = 299 pm/V, εr = 920.03, tanδ = 0.0452, Pr = 18 μC/cm2, Tc = 384 °C, Ec = 14 kV/cm). The relaxor behavior of NKLN-CZ ceramics was induced by the introduction of CaZrO3, which may lead to A-site cation disorder and show diffuse phase transition characteristics. Hence, it broadens the temperature range of phase transformation and mitigates thermal instability for piezoelectric properties in NKLN-CZ ceramics. The value of kp for NKLN-CZ ceramics is held at 27.7-31% (variance of kp < 9%) in the range from -25 to 125 °C. The results indicate that lead-free ceramics NKLN-CZ is one of the hopeful temperature-stable piezoceramics for practical application in electronic devices.

Phase diagrams of zirconium dioxide systems with yttrium and scandium oxides

The literature data on the study of phase equilibria in systems zirconia with yttria and scandia are analysed. Possible schemes of low-temperature phase equilibria in ZrO2-Y2O3 and ZrO2-Sc2O3 systems are presented taking into account the third law of thermodynamics. The coordinates of non-variant transformations in these systems are tabulated. A sign of non-equilibrium states is the observation of non-diffusion processes of ordering of solid solutions. The modified cryoscopy method is used to calculate the distribution coefficients of scandia and yttria during the crystallization of the ZrO2 melt. The possibilities for the existence of a set of ordered phases in the ZrO2-Y2O3 system and diffuse phase transition in the cubic modification of zirconia are discussed.

L1-Theory for Hele-Shaw flow with linear drift

The main goal of this paper is to prove [Formula: see text]-comparison and contraction principles for weak solutions of PDE system corresponding to a phase transition diffusion model of Hele-Shaw type with addition of a linear drift. The flow is considered with a source term and subject to mixed homogeneous boundary conditions: Dirichlet and Neumann. The PDE can be focused to model for instance biological applications including multi-species diffusion-aggregation models and pedestrian dynamics with congestion. Our approach combines DiPerna-Lions renormalization type with Kruzhkov device of doubling and de-doubling variables. The [Formula: see text]-contraction principle allows afterwards to handle the problem in a general framework of nonlinear semigroup theory in [Formula: see text], thus taking advantage of this strong theory to study furthermore existence, uniqueness, comparison of weak solutions, [Formula: see text]-stability as well as many further questions.

Synergistic effects of Zn B-site substitution in lead-free Ba0.95Ca0.05Ti0.92Sn0.08O3 ferroelectric ceramics for enhancing piezoelectric properties in energy harvesting applications

In this study, lead-free (Ba0.95Ca0.05)(Ti0.92Sn0.08)O3 (BCTS) and (Ba0.95Ca0.05)(Ti0.912Sn0.08Zn0.008)O3 (BCTS-Zn) ceramics with large piezoelectric properties were prepared via the conventional solid-state reaction. The effect of Zn B-site substitution on the structural, dielectric, ferroelectric, energy storage, electrocaloric and piezoelectric properties of BCTS ceramics were systematically investigated. X ray diffraction analysis and Raman spectroscopy of BCTS and BCTS-Zn ceramics confirm the formation of pure phase structure with the coexistence of orthorhombic, tetragonal and pseudo cubic phases at room temperature. The introduction of Zn into BCTS lattice resulted in a denser microstructure with larger average grain size which contributed in the enhancement of the dielectric constant maximum by ⁓35%. Furthermore, the substitution of Ti4+ with a small amount of Zn2+ (0.008) induced a shift in TR-O, TO-T and TT-C transitions towards higher temperatures in addition to an increase in the diffused phase transition character. Moreover, with Zn substitution, an amelioration in the maximum energy storage efficiency is observed from ⁓83% in BCTS ceramic to ⁓88% in BCTS-Zn ceramic. The electrocaloric properties were investigated using the direct and indirect methods. The highest value of the electrocaloric temperature change ΔT = 0.361 K at 319 K was calculated for BCTS ceramic using Maxwell approach with a relatively low electric field of 17.55 kV/cm. For BCTS-Zn ceramic, the enhancement of the piezoelectric properties (d33 = 420 pC/N, g33 = 23.02 mV/mN, FoM = 9.66 pm2/N) is attributed to the synergistic effect of the (O-PC-T) multiphase coexistence, large average grain size and high density of the ceramic. This study reveals that B site Zn substitution in BCTS lattice is an effective approach to improve the piezoelectric properties of the ceramic for energy harvesting applications.

Investigation of relaxor and diffuse dielectric phase transitions of Ba1-XBixTi0.8Fe0·2O3 materials

Different doping elements have been used to enhance the dielectric properties of BaTiO3 ceramic. In this work, the effect of substitution of Ba by Bi in A site and Ti by Fe in B site on structural, dielectric and electrical properties of Ba1-xBixTi0.80Fe0·20O3 ceramics at (x = 0.00, 0.05, 0.10 and 0.15) was investigated by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy (SEM), Mössbauer spectroscopy as well as dielectric measurements. The Rietveld refinement results revealed that the prepared compounds crystallize in both tetragonal (P4mm) and hexagonal (P63/mmc) phases for x = 0.00 and 0.05 while at x = 0.10 and 0.15, the hexagonal phase disappears and only the tetragonal phase is fitted. The Raman spectra confirmed the disappearance of hexagonal phase in benefit of tetragonal phase as the Bi3+ substitution increases. Based on Mössbauer analyses results, all the samples are in paramagnetic state at room temperature and the Fe is oxidized under Fe3+ without the presence of Fe2+ or Fe4+ ions. The dielectric measurements as function of temperature are studied and tree broad and relaxor phase transitions were detected: from rhombohedral to orthorhombic phase TR-O and to tetragonal ferroelectric phase TO-T then to cubic paraelectric phase Tm. These phase transitions were displaced to the lower temperature with increasing of Bi3+ substitution. The values of ε′r increase gradually with increasing of Bi3+contents which confirmed the enhancement of dielectric properties of BaTi0·80Fe0·20O3 by Bi substitution on Ba site. The diffuse phase transitions were described by fitting the modified Uchino relation. The Cole–Cole analyses showed that both the grain and grain boundaries resistivity values are higher for Bi3+ substituted samples which are responsible to the dielectric properties improvement.

Structure, morphological and dielectric properties of BZT-BST ceramics

Barium zirconate titanate (BZT), a relaxor ferroelectric ceramic based on barium titanate (BT), has received substantial research. In this study, Ba(Zr0.2Ti0.8)O3 and Ba0.85Sr0.15TiO3 were separately prepared by solid state method and thereafter they were mixed in the following ratio (1-x){Ba(Zr0.2Ti0.8)O3} – x{Ba0.85Sr0.15TiO3} (x = 0, 0.1, 0.2) (BZT-BST) to make ceramic composite using high energy ball mill. The structure, morphology, and dielectric properties of these composites have been systematically studied. The crystal structure of the BZT-BST composite was determined by X-ray diffraction technique. The XRD pattern shows a well-developed tetragonal perovskite crystal structure. Without a second phase, all samples exhibit the perovskite structured BZT diffraction peaks. Permittivity measurements show that the relative permittivity (εr) of the composite increases as the amount of BST increases from × = 0 to × = 0.1, but then decreases at × = 0.2, indicating a broad transition in dielectric constant. The observed Curie temperatures (Tc) for all the compositions mentioned are 31 °C, 36 °C, and 43 °C, of ​​which the dielectric maximum for each composition is found to be ∼ 5000, 6100, and 3810 at the frequency of 1 kHz. It can be seen that the relative permittivity (εr) of all three BZT-BST compositions decreases gradually with increasing frequency. At low frequency, there are several different polarizations mechanisms. However, at high frequencies, only electronic displacement polarization exists. Morphological analysis of the sintered samples by Field emission scanning electron microscopy (FESEM) shows that the pure BZT ceramics have numerous pores. The compactness of BZT-BST ceramics was significantly enhanced by the addition of BST. The grain size of BZT-BST ceramics increases with increasing BST content. Pure BZT ceramics exhibit ferroelectric diffusion phase transition characteristics with weak relaxation behaviour. BZT-BST composites exhibit increasing relaxation behaviour with increasing BST content. These may be the most promising candidate materials for capacitor applications.

Features of Ca1-xYxF2+x solid solution heat capacity behavior: diffuse phase transition

Features of Ca1-xYxF2+x solid solution heat capacity behavior: diffuse phase transition

Achieving ultrabroad temperature stability range with high dielectric constant and superior energy storage density in KNN–based ceramic capacitors

Multilayer ceramic capacitors (MLCCs) had become an important component of many electronic devices on account of its miniaturization, high capacitance and reliability. To satisfy the requirements of MLCCs, the temperature–insensitivity and dielectric properties of the dielectric ceramics were urgent to be enhanced. In our work, (1–x)K0.5Na0.5NbO3–xBi(Li0.5Nb0.5)O3 (abbreviated to KNN–xBLN) were successfully synthesized by traditional solid state reaction method. On the one hand, the doping BLN induced the diffused phase transition and broadened the dielectric anomaly peaks, which improved the temperature insensitivity of KNN-based ceramics. On the other hand, the nanosized grains and dense microscopy boosted the breakdown electric field. Ultimately, the KNN–0.175BLN samples presented the excellent dielectric properties with high dielectric constant (1735) and low dielectric loss (1.9%) at room temperature with a wide temperature stability range (–62 – 300 °C), which exhibited the wider temperature stability range than X9R specification. Meanwhile, the x = 0.175 samples also achieved a high recoverable energy storage density of 3.71 J/cm3 under the breakdown electric field of 360 kV/cm. The designed KNN–based dielectric materials were expected to be applicable to the energy storage capacitor with standed high operating temperature.

Effect of sintering temperature on microstructure, dielectric and ferroelectric properties of BaTiO3 ceramics

BaTiO3 ceramic powders are prepared by the solid phase reaction method. BaTiO3 ceramic powders are sintered at different temperatures for 3 h. The tetragonal phase of BaTiO3 powder is confirmed by XRD. It was found that as the sintering temperature increased, the grain size, density, and dielectric constant of BaTiO3 ceramics increased. All the BaTiO3 ceramic samples sintered at various temperatures for 3 h show the diffuse phase transition and the diffuseness parameter and curie-Weiss constant are also calculated. BaTiO3 ceramic samples sintered at 1200 °C show well-grown grain boundaries. The ferroelectric nature of sintered BaTiO3 ceramic samples studied using P-E hysteresis measurements.