Showing papers on "Ferroelectric ceramics published in 2018"

Ultrahigh piezoelectricity in ferroelectric ceramics by design

Abstract: Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d33 of up to 1,500 pC N-1 and dielectric permittivity e33/e0 above 13,000 in a Sm-doped PMN-PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.

Chemical heterogeneity and approaches to its control in BiFeO3–BaTiO3 lead-free ferroelectrics

Abstract: 1 mol% MnO2 was used to improve electrical resistivity of lead-free 0.75BiFeO3–0.25BaTiO3 (75BFBT) ferroelectric ceramics; the materials were perovskite structured with major rhombohedral (R3c) phase. The method of incorporation of MnO2 was found to exert a significant influence on the structure, microstructure and electrical properties. Chemical heterogeneity in the form of core–shell grain microstructures was observed when MnO2 was added into the undoped calcined powder, in contrast to the relatively homogeneous materials that resulted from adding MnO2 into the precursor oxide mixture prior to calcination. Compositionally graded regions were detected across the grains consisting of a BF-rich core and BF-depleted shell. The occurrence of core–shell type microstructures led to various characteristic features including a high cubic phase fraction, contrast between ordered ferroelectric domain configurations in the rhombohedral core and the relatively featureless pseudo-cubic shell, constrained ferroelectric domain switching, and two distinct anomalies in dielectric permittivity at temperatures of 485 and 635 °C. The latter features are attributed to separate phase transitions in the relaxor ferroelectric shell and normal ferroelectric core regions respectively. The application of a thermal quenching procedure caused the formation of ferroelectric domain structures throughout the microstructure and resulted in dramatically enhanced ferroelectric switching behaviour. For example, the remnant polarisation of the as-sintered 75BFBT ceramic increased from 0.06 to 0.31 C m−2 after air-quenching. These effects are tentatively attributed to nanoscale phase segregation in the shell region of the as-sintered ceramics, resulting from thermodynamic immiscibility between the BF and BT solid solutions.

Ultrahigh recoverable energy storage density and efficiency in barium strontium titanate-based lead-free relaxor ferroelectric ceramics

Abstract: Recently, dielectrics for energy storage have been attracting increasing attention due to their ultrahigh power density. However, the widespread application of dielectrics remains limited by their low energy density. In this work, lead-free single-phase relaxor (1 − x)Ba0.55Sr0.45TiO3-xBiMg2/3Nb1/3O3 [(1 − x)BST-xBMN] (x = 0, 0.05, 0.07, and 0.10) bulk ceramics were prepared by a conventional solid-state reaction process. The dielectric properties, the relaxor behavior, and the energy storage properties were explored in detail. With increasing BMN content, the observed increase in activation energy (Ea) and the decrease in freezing temperature (Tf) indicate that the coupling between polar nano-regions (PNRs) gradually weakened, leading to the decrease in remanent polarization (Pr) and the increase in energy storage efficiency (η). For the composition x = 0.07, the breakdown strength (BDS) significantly increased from 240 kV cm of pure BST to 450 kV cm. Finally, large Wrec (4.55 J cm3) and high η (81.8%) were achieved in 0.93BST-0.07BMN ceramics. The results demonstrate that the (1 − x)BST-xBMN ceramics have superior potential for use in advanced pulsed power capacitors.

Tunable Luminescence Contrast in Photochromic Ceramics (1 – x)Na0.5Bi0.5TiO3–xNa0.5K0.5NbO3:0.002Er by an Electric Field Poling

Abstract: A binary solid solution of Er3+-doped (1 – x)Na0.5Bi0.5TiO3–xK0.5Na0.5NbO3 (x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) ferroelectric ceramics has been developed, and a reversible photochromic (PC) reaction and its associated luminescence modulation are realized via alternating the 405 nm light irradiation and thermal stimulation (200 °C). The basic crystal structure, domain structure, ferroelectricity, and dielectric behavior of the ceramics were measured. A moderate luminescence contrast ΔRt over 50% is obtained in the fresh samples. Meanwhile, a greatly enhanced luminescence contrast ΔRt is obtained via an electric poling for compositions x = 0.02, 0.04, 0.06. For example, ΔRt is promoted from 53.4 to 85.3% for x = 0.02. However, the luminescence contrast ΔRt of compositions x = 0.08, 0.10, 0.12 is depressed after poling. The mechanisms of enhanced PC reaction and luminescence contrast ΔRt are discussed and proposed. The present study may open a window for enhancing the PC reaction.

Boosting Photovoltaic Output of Ferroelectric Ceramics by Optoelectric Control of Domains

Abstract: Photo-ferroelectric single crystals and highly oriented thin-films have been extensively researched recently, with increasing photovoltaic energy conversion efficiency (from 0.5% up to 8.1%) achieved. Rare attention has been paid to polycrystalline ceramics, potentially due to their negligible efficiency. However, ceramics offer simple and cost-effective fabrication routes and stable performance compared to single crystals and thin-films. Therefore, a significantly increased efficiency of photo-ferroelectric ceramics contributes toward widened application areas for photo-ferroelectrics, e.g., multisource energy harvesting. Here, all-optical domain control under illumination, visible-range light-tunable photodiode/transistor phenomena and optoelectrically tunable photovoltaic properties are demonstrated, using a recently discovered photo-ferroelectric ceramic (K0.49Na0.49Ba0.02)(Nb0.99Ni0.01)O2.995. For this monolithic material, tuning of the electric conductivity independent of the ferroelectricity is achieved, which previously could only be achieved in organic phase-separate blends. Guided by these discoveries, a boost of five orders of magnitude in the photovoltaic output power and energy conversion efficiency is achieved via optical and electrical control of ferroelectric domains in an energy-harvesting circuit. These results provide a potentially supplementary approach and knowledge for other photo-ferroelectrics to further boost their efficiency for energy-efficient circuitry designs and enable the development of a wide range of optoelectronic devices.

Large Flexoelectriclike Response from the Spontaneously Polarized Surfaces in Ferroelectric Ceramics.

Abstract: Nonpoled ferroelectric ceramics are thought to be nonpolar because of randomly oriented grains and the formation of ferroelectric domains in the grains. Here, we discover the surfaces ($\ensuremath{\sim}\mathrm{several}\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ thick) of ferroelectric ceramics are spontaneously polarized. Because the orientations of ferroelectric polarization of the opposite surfaces are antiparallel, ferroelectric ceramics are nonpolar as a whole. However, the ceramics exhibit a strong flexoelectriclike electromechanical response from the piezoelectric response of the polarized surfaces if they are asymmetrically strained (such as bending). Our results reveal a major mechanism to resolve one important but largely unresolved issue: the experimentally measured flexoelectric effect is typically orders of magnitude larger than the theoretically predicted value in ferroelectrics.

Origin of composition-insensitive electrostrictive coefficient and continuous decrease of domain wall density in (1-x)NaNbO3-xBaTiO3 lead-free ferroelectrics

Abstract: Perovskite ferroelectric ceramics with giant electrostrictive coefficient Q33 have attracted much attention due to their high strain response with ultralow hysteresis. In this work, the electrostrictive properties as well as domain morphology of the lead-free (1−x)NaNbO3-xBaTiO3 (NN-xBT) (0.10 ≤ x ≤ 0.27) system were investigated systematically. A composition-insensitive Q33 of 0.0406 m4/C2 is identified in the NN-xBT ceramics (0.15 ≤ x ≤ 0.27). An ab initio computation indicates that transverse Q12 would play an important role in understanding of the composition-insensitive Q33. Furthermore, distinctively banding domains and inhomogeneous distribution of nanodomains were observed in NN-xBT by piezoresponse force microscopy. A continuous decrease of domain wall density was identified with respect to the increase of x. This study would not only deepen our understanding of the origin of composition-insensitive Q33 in NN-BT and other related systems, but also provide a way to enhance the Q33, i.e., by forming the solid solutions with end members, which possess high Q12.

Large Electrocaloric Effect in Lead-free Ba(HfxTi1–x)O3 Ferroelectric Ceramics for Clean Energy Applications

Abstract: Ba(HfxTi1–x)O3 ferroelectric ceramics were prepared by a conventional solid-state reaction process, and the correlation of structure, dielectric, ferroelectric, and electrocaloric properties were studied. The consequences indicated that the TC of Ba(HfxTi1–x)O3 ceramics decreased, while TT–O and TO–R increased with the increase of hafnium content. Large electrocaloric effect values of 1.64 K (117 °C) and 1.21 K (76 °C) were observed for Ba(HfxTi1–x)O3 with x = 0.05 compositions. And, corresponding electrocaloric coefficients respectively were 0.33 and 0.24 K·mm·kV–1. In addition, compared with the second-order phase transition region, larger electrocaloric coefficients (ΔTf /ΔE ≥ 0.19 K·mm·kV–1) were obtained in the first-order phase transition region for all compositions. Meanwhile, the maximum values of electrocaloric coefficients ΔTf /ΔE = 0.38 K·mm·kV–1 was achieved in a smaller electric field for Ba (HfxTi1–x)O3 with x = 0.03 compositions.

Design, synthesis and processing of PVDF-based dielectric polymers

Abstract: Due to the appealing piezoelectric, pyroelectric, and ferroelectric (FE) properties, poly(vinylidene fluoride) (PVDF)-based dielectric polymers have been attracting great attention from both the academic and industrial communities. Depending on the molecular structure and the processing method, PVDF-based dielectric polymers can exhibit rich dielectric polarisation behaviours covering normal FE, relaxor FE, anti-FE-like and linear dielectric responses, which enables a wide spectrum of application fields such as non-volatile memories, piezoelectric and pyroelectric sensors, actuators, electrocaloric refrigeration, and film capacitors. In this study, the authors first briefly introduce the current practical/promising applications of PVDF-based dielectric polymers, and the corresponding optimum dielectric polarisation behaviour and crystal structure are proposed accordingly. The chemical synthesis and modification strategies for obtaining various fluoropolymers beyond PVDF homopolymer are then summarised with an emphasis on the relationship between the molecular structure and the dielectric polarisation behaviour. In addition, the effect of processing methods on the crystal structure and dielectric properties of the PVDF-based polymers is discussed. Finally, some newly developed processing techniques applicable to PVDF-based polymers are described.

Giant room-temperature electrostrictive coefficients in lead-free relaxor ferroelectric ceramics by compositional tuning

Abstract: A thermotropic phase boundary between non-ergodic and ergodic relaxor phases is tuned in lead-free Bi1/2Na1/2TiO3-based ceramics through a structural transition driven by compositional modification (usually named as “morphotropic approach”). The substitution of Bi(Ni1/2Ti1/2)O3 for Bi1/2(Na0.78K0.22)1/2TiO3 induces a transition from tetragonal to “metrically” cubic phase and thereby, the ergodic relaxor ferroelectric phase becomes predominant at room temperature. A shift of the transition temperature (denoted as TF-R) in the non-ergodic-to-ergodic phase transition is corroborated via temperature-dependent dielectric permittivity and loss measurements. By monitoring the chemical composition dependence of polarization-electric field and strain-electric field hysteresis loops, it is possible to track the critical concentration of Bi(Ni1/2Ti1/2)O3 where the (1 − x)Bi0.5(Na0.78K0.22)0.5TiO3-xBi(Ni0.5Ti0.5)O3 ceramic undergoes the phase transition around room temperature. At the Bi(Ni0.5Ti0.5)O3 content of x = ...

High piezoelectric sensitivity and hydrostatic figures of merit in unidirectional porous ferroelectric ceramics fabricated by freeze casting

Abstract: High performance lead zirconate titanate (PZT) ceramics with aligned porosity for sensing applications were fabricated by an ice-templating method. To demonstrate the enhanced properties of these materials and their potential for sensor and hydrophone applications, the piezoelectric voltage constants (g33 and g31), hydrostatic parameters (dh, gh, −d33/d31, dh·gh and dh·gh/tanδ) and AC conductivity as a function of the porosity in directions both parallel and perpendicular to the freezing temperature gradient were studied. As the porosity level was increased, PZT poled parallel to the freezing direction exhibited the highest dh, −d33/d31 and figures of merit dh·gh, dh·gh/tanδ compared to the dense and PZT poled perpendicular to the freezing direction. The gh, g33 and g31 coefficients were highest for the PZT poled perpendicular to the freezing direction; the gh was 150%–850% times higher than dense PZT, and was attributed to the high piezoelectric activity and reduced permittivity in this orientation. This work demonstrates that piezoelectric ceramics produced with aligned pores by freeze casting are a promising candidate for a range of sensor applications and the polarisation orientation relative to the freezing direction can be used to tailor the microstructure and optimise sensitivity for sensor and hydrostatic transducer applications.

Investigations on the phase transition of Mn-doped BaTiO3 multifunctional ferroelectric ceramics through Raman, dielectric, and magnetic studies

Abstract: BaTiO3 (BTO) and BaTi1−xMnxO3 (x = 0.25, 0.50, 0.75 mol%) ceramic materials have been prepared by the sol–gel combustion method. X-ray diffraction (XRD) has been carried out to characterize the phase purity and crystal structure of the prepared compounds, and all XRD patterns suggest tetragonal structure with the phase group of P4mm. The variation in the estimated lattice parameters confirms the incorporation of Mn atoms at Ti site of BTO. Raman spectroscopy studies under various temperatures suggest a phase transition from tetragonal to cubic phase at ~433 K, identified by a distinct Raman mode at 308 cm−1. As Raman modes are getting softened by Mn doping, phase transition temperature of the Mn-doped compounds is significantly decreased from 473 K (x = 0%) to 433 K (x = 0.75%). Dielectric properties such as permittivity and dielectric loss as the function of frequency under various temperatures have two distinct dielectric anomalies (i) at 393 K associated to tetragonal to cubic phase transition and (ii) at 550 K due to oxygen vacancy defect in the samples. Observation of weak ferromagnetism at 2, 300, and 400 K in the M (H) and ZFC-FC curve, suppose its origin due to an intriguing exchange interaction between Mn and oxygen vacancies.

Crystal structural evolution and hybrid improper ferroelectricity in Ruddlesden-Popper Ca3-xSrxTi2O7 ceramics

Abstract: Hybrid improper ferroelectricity (HIF) has been proposed as a candidate approach to create room-temperature multiferroic materials with an intrinsic electric-field controlled magnetism effect, and HIFs in bi-layered Ruddlesden-Popper Ca3-xSrxTi2O7 ceramics have been confirmed in the present work. The ferroelectric hysteresis loops are observed in these ceramics at room temperature, and the polar orthorhombic structures with oxygen octahedral rotation and tilt modes have been confirmed by room-temperature X-ray powder diffraction. The amplitudes of oxygen octahedral rotation and tilt modes decrease with the increasing x value, which in turn leads to the decrease of remnant polarization in these ceramics. A first-order phase transition has been evidenced by the differential scanning calorimetry measurement, and the temperature of phase transition decreases linearly with the increasing content of strontium cations. It is found that the amplitude of oxygen octahedral distortion is the dominating factor that a...

Symmetry changes during relaxation process and pulse discharge performance of the BaTiO3-Bi(Mg1/2Ti1/2)O3 ceramic

Abstract: Lead free relaxor ferroelectrics have attracted continuing interest due to their outstanding and eco-friendly properties. In this paper, dielectric relaxation behavior of the 0.6BaTiO3-0.4Bi(Mg1/2Ti1/2)O3 ceramic (BT-40BMT), which is a typical lead free relaxor ferroelectric, is theoretically and experimentally investigated. At first, the observed dielectric relaxation was quantitatively characterized by a statistical model, indicating that the minority co-related polar nano regions (PNRs) dominate the total polarization. Kinetics of the PNRs were subsequently studied by micro-Raman measurements performed at various temperatures. Here, the relaxation of written domains formed by the piezoresponse force microscopy (PFM) tip-bias induced electric field was also studied, which describes the polarization retention performance of BT-40BMT. The absence of ferroelectric signal contribution in local switching was also confirmed by the contact mode Kelvin PFM technique, indicating the lack of local ferroelectricity. Moreover, the temperature insensitive energy storage property from 293 K to 443 K was obtained. High voltage pulsed discharge behavior was also investigated by using the pulsed current. A power density of 7.9 × 108 W/kg is obtained under a pulsed voltage of 50 kV. Combined with the fast discharge time, the 0.6BaTiO3-0.4Bi(Mg1/2Ti1/2)O3 ceramic is considered as a candidate material for high voltage pulse power applications.

The NbO6 octahedral distortion and phase structural transition of Eu3+-doped K0.5Na0.5NbO3–xLiNbO3 ferroelectric ceramics

Abstract: A small quantity of Eu3+ ions was doped in the lead-free ferroelectric K0.5Na0.5NbO3-xLiNbO3 (KNN-xLN, 0≤x≤0.08) ceramics to investigate the NbO6 octahedral distortion induced by the increasing LN content. In addition, the phase structure, ferroelectric and photoluminescence properties of K0.5Na0.5NbO3-xLiNbO3:0.006Eu3+ (KNN-xLN:0.006Eu3+) lead-free piezoelectric ceramics were characterized. All the X-ray diffraction, Raman spectra, dielectric constant versus temperature measurements and the photoluminescence of Eu3+ ions demonstrated that the prepared ceramics undergo a polymorphic phase transition (PPT, from orthorhombic to tetragonal phase transformation) with the rising LN content, and the PPT region locates at 0.05≤x≤0.06. The ferroelectric properties, Raman intensity ratios and photoluminescence intensity ratios show similar variations with the increasing LN content, all with a maximum value achieved at the PPT region. We believe that the close relationship among the ferroelectric properties, Raman intensity ratios and photoluminescence intensity ratios is caused by the NbO6 octahedral distortion. The photoluminescence of Eu3+ ion was discussed basing on the crystal-symmetry principle and Judd-Ofelt theory. This article is protected by copyright. All rights reserved.

Experimental evidence of charged domain walls in lead-free ferroelectric ceramics: light-driven nanodomain switching

Abstract: The control of ferroelectric domain walls at the nanometric level leads to novel interfacial properties and functionalities. In particular, the comprehension of charged domain walls, CDWs, lies at the frontier of future nanoelectronic research. Whereas many of the effects have been demonstrated for ideal archetypes, such as single crystals, and/or thin films, a similar control of CDWs on polycrystalline ferroelectrics has not been achieved. Here, we unambiguously show the presence of charged domain walls on a lead-free (K,Na)NbO3 polycrystalline system. The appearance of CDWs is observed in situ by confocal Raman microscopy and second harmonic generation microscopy. CDWs produce an internal strain gradient within each domain. Specifically, the anisotropic strain develops a crucial piece in the ferroelectric domain switching due to the coupling between the polarization of light and the ferroelectric polarization of the nanodomain in the (K,Na)NbO3 ceramic. This effect leads to the tuning of the ferroelectric domain switching by means of the light polarization angle. Our results will help to understand the relevance of charged domain walls on the ferroelectric domain switching process and may facilitate the development of domain wall nanoelectronics by remote light control utilizing polycrystalline ferroelectrics.

Increase in depolarization temperature and improvement in ferroelectric properties by V5+ doping in lead-free 0.94(Na0.50Bi0.50)TiO3-0.06BaTiO3 ceramics

Abstract: A detailed study was carried out to investigate the effects of poling on structure, vibrational, dielectric, and ferroelectric properties of donor-doped (V5+ at Ti4+-site) lead-free Na0.47Bi0.47Ba0.06Ti(1-x)VxO3, (x = 0, 0.01, and 0.03) ceramics fabricated via a modified sol-gel method. Rietveld refinement of synchrotron radiation source powder x-ray diffraction data showed that unpoled samples are in rhombohedral R3c phase whereas poled samples showed a mix rhombohedral R3c and tetragonal P4mm phases at ambient temperature, due to a long-range order established in lattice system after poling. V+5 doping increases the rhombohedral distortion in unpoled and poled samples while it reduces the tetragonality in poled samples. Vibrational study revealed that unpoled samples have more lattice disorder compared to poled samples. X-ray absorption near edge spectroscopy measurement confirmed that Ti and V are in 4+ and 5+ oxidation states, respectively, for all poled and unpoled samples. The average grain size was found to decrease from 5.6 ± 0.5 μm for x = 0 to 1.0 ± 0.2 μm for x = 0.03. Depolarization temperature was found to increase significantly in poled samples from ∼104 °C for undoped sample to 150 °C for the sample with 1% vanadium substitution. Drastic improvements in ferroelectric and dielectric properties are explained in terms of structural changes. High remnant polarization Pr ∼ 31.4 μC/cm2 and moderately low coercive field Ec ∼ 20 kV/cm have been observed at an applied electric field of ∼35 kV/cm for the sample with 1% vanadium substitution which makes it an attractive candidate for ferroelectric applications.

High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

Abstract: Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ∼ 3.7 × 10−8 C cm−2 K−1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10−10 m/V, 2.89 × 10−2 m2/C, and 1.15 × 10−5 Pa−1/2 at 1 kHz and 1.32 × 10−10 m/V, 2.70 × 10−2 m2/C, and 1.09 × 10−5 Pa−1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ∼400 × 10−8 C cm−2 K−1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

Complete stress-induced depolarization of relaxor ferroelectric crystals without transition through a non-polar phase

Abstract: The development of relaxor ferroelectric single crystal technology is driven by the ability to tailor ferroelectric properties through domain engineering not achievable in polycrystalline materials. In this study, three types of domain-engineered rhombohedral Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 crystals were subjected to transverse high strain rate loading. The experimental results indicate that the domain configuration has a significant effect on the stress-induced depolarization and the associated charge released. A complete depolarization of the single-domain crystals with 3m symmetry is observed, while multidomain crystals with 4mm and mm2 symmetries retain a fraction of their initial remanent polarization. The complete depolarization of single-domain crystals is unique without transition to a non-polar phase, with a stress-induced charge density of 0.48 C/m2. This is up to three times higher than that of the multidomain crystals and PbZrxTi1−xO3 ferroelectric ceramics that are critical for ultrahigh-power transducer applications. The main offering of this work is to propose a detailed mechanism for complete stress-induced depolarization in ferroelectric crystals which does not involve an intermediate transformation to a non-polar phase.

Porous Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 Ceramics for Pyroelectric Applications

Abstract: Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ferroelectric ceramics were fabricated using a solid-state reaction consisting of BCZT and poly(methyl methacrylate)(PMMA) (2%, 4%, 8% and 10% by wt.%) as a pore former. By increasing the PMMA content from 0% to 10%, porosity increased from 8% to 29%. It was found that the dielectric constant (er) decreased and the dielectric loss (tanδ) increased with increasing porosity. At 29% porosity, er of the BCZT was found to decrease more, from 3481 to 1117 at 5 kHz and at room temperature. The dielectric constant and volume-specific heat capacity decreased with the increase in porosity which ultimately improved the pyroelectric figure-of-merits (FOMs). Further, the pyroelectric FOMs were estimated and found to be improved at optimum porosity.

Investigation on electrical properties of BCZT ferroelectric ceramics prepared at various sintering conditions

Abstract: The influence of sintering conditions on phase formation, density, microstructure and electrical properties of BCZT ceramics wer investigated. The BCZT (Ba0.85Ca0.075Zr0.1Ti0.9O3) ceramics were fab...