Barium Calcium Zirconate Titanate Research Articles

Kesan Penggantian Litium ke atas Struktur, Sifat Fizikal dan Sifat Elektrik terhadap Seramik BCZT

The invention of novel lead-free piezoelectric materials with ABO3 perovskite structure, based on barium calcium zirconate titanate (BCZT) for application in various device especially in sensor application. In this work, BCZT with lithium substitution at the calcium site with composition Ba0.85Ca0.15-xLi2xZr0.1Ti0.9O3 (x = 0.00, 0.03, 0.06, 0.09 and 0.12) were synthesized by using the conventional, solid state reaction method. The influence of different Li content on the structure, microstructure, density, and electrical properties were investigated. The results show that substitution led to the improvement of the physical and electrical properties of the piezoelectric ceramic materials. The physical properties show the largest grain size and the highest value of density, ρ which is 4.158 g/cm3 for x = 0.06. This physical properties led to the highest value of piezoelectric coefficient, d33, remnant polarisation, Pr and saturated polarization, Ps which are 304.6 pC/N, 3.27 µC/cm2, and 5.54 µC/cm2, respectively, while the highest dielectric constant, ɛr was 3994 when x = 0.12.

Dielectric and Ferroelectric Performances of Y, Mn Co-doped Barium Calcium Zirconate Titanate Based Lead-Free Piezoceramics

Dielectric and Ferroelectric Performances of Y, Mn Co-doped Barium Calcium Zirconate Titanate Based Lead-Free Piezoceramics

Temperature Effect on Fatigue Behavior of BCZT Ceramics and Defects Analysis by Synchrotron X-Ray Absorption Spectroscopy

This paper presents the effect of temperature on the electrical fatigue behavior of barium calcium zirconate titanate (Ba0.85Ca0.15Zr0.1Ti0.9O3) ceramics. Fatigue degradation and its practical applications are a significant problem in piezo/ferroelectric ceramics. Fatigue-induced domain orientations, physical damage or microcracking, and defects were studied using, X-ray diffraction (XRD), synchrotron X-ray absorption spectroscopy (XAS), and scanning electron microscope (SEM) techniques. The remnant polarization (Pr) decreased with the number of fatigue cycles, and the rate at which the decrease occurred was different for different fatigue temperatures. The weak and strong domain wall pinning effects played a major role in the Pr value with respect to the fatigue cycles. The sharp rise of Ec value at 5 × 103 cycles and the abrupt decrease of Ec values after 5 × 104 cycles could be due to the field screening effect and heat recovery of pinned domains. The abrupt decrease of Pr values after 5 × 105 cycles could be due to physical damage near the electrode interface region, and the same physical damage decreased with the increase in fatigue temperature. The near-edge X-ray absorption fine structure (NEXAFS) study was utilized to evaluate the oxygen-related defect concentration.

Additively Manufactured Ferroelectric Particulate Composites for Antimicrobial Applications

AbstractA polarized ferroelectric material can initiate the micro‐electrolysis of water molecules which leads to the formation of reactive oxygen species (ROS) in an aqueous solution resulting in selective bacteria killing. This study presents the fabrication, characterization, and antimicrobial performance of poled ferroelectric particulate composites. Barium calcium zirconate titanate (BCZT) micro‐powder is synthesized by a solid‐state reaction and mechanically mixed with polycaprolactone (PCL) to be subsequently fed into the 3D bioprinter for the fabrication of porous PCL‐BCZT structures at four different ceramic loadings (0, 10, 20, 30 wt%). For the examination of material's capacity to handle extremely high contamination, the composites are exposed to a high inoculum of bacteria (Escherichia coli ATCC 25922) ≈70% of E. coli degradation is recorded at the end of 15 min without any external intervention. The surface selective bacterial degradation can be attributed to the generated reactive oxygen species, the large surface area of the porous samples and polymer matrix's hydrophobic nature, behavior which can be reflected in the composites with 30 wt% of BCZT loading exhibiting the best antimicrobial performance among the other state‐of‐the‐art ferroelectrics. Overall, these results indicate that the poled composites have a great potential as antimicrobial materials and surfaces.

Annealing Temperature-Dependent Structural, Optical, and Electrical Properties of [(Ba1−zCaz)(Zr0.1Ti0.9)O3], (z = 0.155), Films

Thin films were deposited, on quartz and p-Si (100) substrates, by radio frequency (RF) sputtering of ceramic barium calcium zirconate titanate [(Ba1−zCaz)(Zr0.1Ti0.9)O3], (z = 0.155), target. The as-deposited films were annealed for one hour at different temperatures, between 500 °C and 800 °C. The occurrence of film crystallization was observed on annealing at and above 600 °C. However, films peeled out on annealing at 800 °C. The structure, optical transmittance, dielectric constant and leakage current of the prepared films (hereafter referred to as BCZT0.9 films), annealed at different temperatures, were measured. Refractive index and optical bandgap were obtained from the measured optical transmittance of the films deposited on quartz substrates and annealed at different temperatures. The optical bandgap of the BCZT0.9 films was found to reduce from 4.24 to 3.87 eV with the increase in annealing temperature. On crystallization, the leakage current density of the prepared films decreased by order of 3, from ∼10−6 for amorphous to ∼10−9 A cm−2 for crystalline films. The current-voltage variations of the prepared films exhibit different conductions for different annealing treatments. The dielectric constant was obtained maximum, 148 (at 1 MHz), and leakage current density minimum, 3.6 × 10−9 A cm−2 (at 3.0 × 102 kV cm−1 electric field), for the films annealed at 750 °C. Electrical properties were observed to improve for the films annealed at 750 °C than other annealed films.

Electroelastic Coupled-Wave Scattering and Dynamic Stress Concentration of Piezoceramics Containing Regular N-Sided Holes

In this paper, the calculation method of dynamic stress concentration around piezoelectric ceramics containing regular n-sided holes under the action of electroelastic coupling wave was studied, and it was applied to promising barium calcium zirconate titanate material. First, electroelastic governing equations were decomposed by using the auxiliary function method, and the solution forms of the elastic wave field and electric field were obtained by using the wave function expansion method. Then, the triangular boundary was simplified to a circular boundary using the mapping function, and the corresponding modal coefficients were determined according to simplified boundary conditions. Finally, the dynamic stress-concentration factor was calculated to characterize the dynamic stress concentration. We performed numerical simulations with a correlation coefficient of (1 − x)[(Ba0.94Ca0.06) (Ti0.92Sn0.08)]-xSm2O3-0.06 mol% GeO2 (abbreviated as (1 − x)BCTS-xSm-0.06G). The numerical calculation results show that the incident wave number, piezoelectric properties, shape parameters of the hole, and deflection angle have a great influence on the dynamic stress around the defect, and some significant laws are summarized through analysis.

Electroelastic Coupled-Wave Scattering and Dynamic Stress Concentration of Triangular Defect Piezoceramics

In this paper, a method to calculate the dynamic stress concentration around the triangular defect of piezoelectric material under electroelastic coupling is studied and applied to the promising barium calcium zirconate titanate. Firstly, the electroelastic governing equation is decomposed by decoupling technique, and the analytical solutions of elastic wave field and electric field are obtained by wave function expansion method. Then, the conformal transformation is used to simplify the triangle boundary into a circular boundary, and the corresponding modal coefficients are determined according to the simplified boundary conditions. Finally, the analytical solution of the dynamic stress concentration factor can be obtained according to the constitutive equation. Substitute the relevant material parameters of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 and set different temperatures, Ce doping amount, and incident wave number for numerical simulation. The numerical results show that the incident wave number, piezoelectric properties, and the shape parameters and deflection angle of the triangular defect have a great influence on the dynamic stress around the defect, and some meaningful laws are summarized through analysis.

Evaluation of the pore morphologies for piezoelectric energy harvesting application

Piezoelectric energy harvesting has attracted significant attention in recent years due to their high-power density and potential applications for self-powered sensor networks. In comparison to dense piezoelectric ceramics, porous piezoelectric ceramics exhibit superiority due to an enhancement of piezoelectric energy harvesting figure of merit. This paper provides a detailed examination of the effect of pore morphology on the piezoelectric energy harvesting performance of porous barium calcium zirconate titanate 0.5Ba(Zr 0.2 Ti 0.8 )O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 (BCZT) ceramics. Three different pore morphologies of spherical, elliptical, and aligned lamellar pores were created via the burnt-out polymer spheres method and freeze casting. The relative permittivity decreased with increasing porosity volume fraction for all porous BCZT ceramics. Both experimental and simulation results demonstrate that porous BCZT ceramics with aligned lamellar pores exhibit a higher remanent polarization. The longitudinal d 33 piezoelectric charge coefficient decreased with increasing porosity volume fraction for the porous ceramics with three different pore morphologies; however, the rate of decrease in d 33 with porosity is slower for aligned lamellar pores, leading to the highest piezoelectric energy harvesting figure of merit. Moreover, the peak power density of porous BCZT ceramics with aligned lamellar pores is shown to reach up to 38 μW cm -2 when used as an energy harvester, which is significantly higher than that of porous BCZT ceramics with spherical or elliptical pores. This work is beneficial for the design and manufacture of porous ferroelectric materials in devices for piezoelectric energy harvesting applications.

Synthesis of lead-free (Ba0.85Ca0.15)(Zr0.1Ti0.82Ce0.08)O3–Na0.5Bi0.5TiO3 ceramic and characterization for structural, electrical and mechanical properties

Barium calcium zirconate titanate (BCZT) and sodium bismuth titanate (NBT) are important lead-free ferroelectrics due to their excellent electrical properties compared to other lead-free as well as lead-based ferroelectrics. In this work, [(1-x)(Ba0.85Ca0.15)(Zr0.1Ti0.82Ce0.08)O3]-[xNa0.5Bi0.5TiO3] (x = 0, 0.25, 0.50, 0.75 and 1.00) was synthesized by conventional solid state technique. Ce-BCZT and NBT were calcined separately, and were mixed in three different weight ratios, Ce-BCZT:NBT = 1:3, 1:1, and 3:1. The differences in phases, morphologies, electrical and mechanical properties of the Ce-BCZT-NBT ceramics were confirmed by x-ray diffractometry – Rietveld refinement, scanning electron microscopy, impedance analysis, Vickers hardness testing and nanoindentation methods. The increment in Curie temperature (Tc) and decrement in elastic modulus with the addition of NBT to Ce-BCZT ceramics were observed. Composition with x = 0.75 (NBT75) is found to have the potential for use in ultrasonic cleaners.

Effect of sintering on the piezoelectric properties and microstructure of lead free (Ba1-xCaxZr0.1Ti0.9O3) (x=0.065) ceramics

In this work, pellet samples of barium calcium zirconate titanate (Ba1-xCaxZr0.1Ti0.9O3, x=0.065) were prepared using solid state reaction route with double sintering. The structural and piezoelectric properties were measured. Further, SEM and EDAX analysis were observed. With different sintering temperature, the density and grain size of the prepared pellet samples were changed and further, their effect in piezoelectric properties has been observed. For the prepared samples, the converse piezoelectric constant (d33*) has been decreased with the increase in sintering temperature. The piezoelectric constant (d33*) was measured highest (153 pm/V) at 1300?C.

Flexible pillar-base structured piezocomposite with aligned porosity for piezoelectric energy harvesting

Flexible piezoelectric energy harvesters have attracted significant attention in recent years due to their ability to convert strain energy associated with bending into electrical energy for low-power wearable electronic devices. Compared with 0–3 type piezoelectric composites, where the piezoelectric phase is isolated within the material, flexible piezoelectric energy harvesters based on a three-dimensional interconnected ceramic skeleton are of particular interest due to their high stress transfer capability and high piezoelectric coefficients. Herein, a three-dimensional interconnected porous barium calcium zirconate titanate (BCZT) pillar-based structure is created via freeze casting, where polydimethylsiloxane (PDMS) is impregnated into the aligned pore channels to form a flexible piezoelectric energy harvester. The effect of porosity on piezoelectric coefficients, ferroelectric properties and energy harvesting performance is investigated in detail. The piezoelectric coefficient and energy harvesting figure of merit are significantly enhanced due to the presence of an aligned pore structure which leads to a high transfer of applied stress into the piezoelectric phase. The highly aligned porosity leads to the creation of a piezoelectric composite with 60 vol% of polymer that exhibits a high output voltage of 30.2 V and current of 13.8 μA. Moreover, the peak power density can reach up to 96.2 μW cm −2 , which is significantly higher than that of nanoparticle-based piezoelectric composites. This work demonstrates a promising prospect of utilizing flexible piezoelectric composites for energy harvesting applications. A flexible piezoelectric energy harvester based on BCZT pillar-base composite with aligned porosity is achieved via a freeze casting technique. Enhanced piezoelectric properties and energy harvesting performance ( V = 30.2 V, I = 13.8 μA at a porosity of 60 vol%) are realized due to the high poling efficiency and improved stress transfer, which is capable of charging capacitors and illuminating commercial LEDs. • Flexible pillar-base structured piezocomposite with highly aligned porosity is developed via freeze casting. • The piezoelectric energy harvesting performance is significantly enhanced due to the presence of an aligned pore structure. • Piezoelectric composite with 60 vol% of polymer exhibits a maximum power density of 96.2 μWcm −2 . • It is demonstrated to have the ability to charge capacitors and illuminate commercial LED bulbs.

Biologically Compatible Lead-Free Piezoelectric Composite for Acoustophoresis Based Particle Manipulation Techniques.

This research paper is concentrated on the design of biologically compatible lead-free piezoelectric composites which may eventually replace traditional lead zirconium titanate (PZT) in micromechanical fluidics, the predominantly used ferroelectric material today. Thus, a lead-free barium–calcium zirconate titanate (BCZT) composite was synthesized, its crystalline structure and size, surface morphology, chemical, and piezoelectric properties were analyzed, together with the investigations done in variation of composite thin film thickness and its effect on the element properties. Four elements with different thicknesses of BCZT layers were fabricated and investigated in order to design a functional acoustophoresis micromechanical fluidic element, based on bulk acoustic generation for particle control technologies. Main methods used in this research were as follows: FTIR and XRD for evaluation of chemical and phase composition; SEM—for surface morphology; wettability measurements were used for surface free energy evaluation; a laser triangular sensing system—for evaluation of piezoelectric properties. XRD results allowed calculating the average crystallite size, which was 65.68 Å3 confirming the formation of BCZT nanoparticles. SEM micrographs results showed that BCZT thin films have some porosities on the surface with grain size ranging from 0.2 to 7.2 µm. Measurements of wettability showed that thin film surfaces are partially wetting and hydrophilic, with high degree of wettability and strong solid/liquid interactions for liquids. The critical surface tension was calculated in the range from 20.05 to 27.20 mN/m. Finally, investigations of piezoelectric properties showed significant results of lead-free piezoelectric composite, i.e., under 5 N force impulse thin films generated from 76 mV up to 782 mV voltages. Moreover, an experimental analysis showed that a designed lead-free BCZT element creates bulk acoustic waves and allows manipulating bio particles in this fluidic system.

Electrical fatigue behavior of Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics under different oxygen concentrations

Fatigue degradation is a significant problem in piezo/ferroelectric materials and their commercial applications. The major causes of electrical fatigue degradation are a domain pinning effect and physical damage such as microcracking. This work reports the fatigue behavior of barium calcium zirconate titanate (Ba0.85Ca0.15Zr0.1Ti0.9O3) under regular and low oxygen concentration silicone oil. Impedence analyzer and LCR meter are employed to analyzer the dielectric properties and it also revealed the relationship between activation energy and oxygen vacancy. X-ray diffraction, synchrotron X-ray absorption spectroscopy, and scanning electron microscope techniques were employed to study the local structural changes, defect development, physical damage and microcracking in the ceramics. FEFF-8.4 simulations were used to determine the oxygen vacancy creation. The study reveals the relationship of oxygen vacancy creation, domain wall pinning, microcracking and the fatigue behavior of the ferroelectric ceramic. The work investigated the dielectric and ferroelectric properties of BCZT ceramics intermes of applied electric field.

Large electromechanical strain and unconventional domain switching near phase convergence in a Pb-free ferroelectric

In many ferroelectrics, large electromechanical strains are observed near regions of composition- or temperature- driven phase coexistence. Phenomenologically, this is attributed to easy re-orientation of the polarization vector and/or phase transition, although their effects are highly convoluted and difficult to distinguish experimentally. Here, we used synchrotron X-ray scattering and digital image correlation to differentiate between the microscopic mechanisms leading to large electrostrains in an exemplary Pb-free piezoceramic Sn-doped barium calcium zirconate titanate. Large electrostrains of ~0.2% measured at room-temperature are attributed to an unconventional effect, wherein polarization switching is aided by a reversible phase transition near the tetragonal-orthorhombic phase boundary. Additionally, electrostrains of ~0.1% or more could be maintained from room temperature to 140 °C due to a succession of different microscopic mechanisms. In situ X-ray diffraction elucidates that while 90° domain reorientation is pertinent below the Curie temperature (TC), isotropic distortion of polar clusters is the dominant mechanism above TC.

Angle dependent synchrotron X-ray absorption spectroscopic structural studies on Ba0.85Ca0.15Zr0.1Ti0.9O3 ferroelectric ceramics

Synchrotron X-ray absorption near edge structure (XANES) technique was employed to investigate the local structure, domain orientation, and Ti off-center displacement in unpoled and poled barium calcium zirconate titanate (BCZT) ceramics. The angular periodicity of domain orientation found to be 180° in poled ceramic and random nature in an unpoled ceramic. The experimental XANES spectra of peak B and E showed sine square dependent and opposite behavior. X-ray Diffraction (XRD), hysteresis loop (P-E), and strain hysteresis loop (S-E) loop results confirm the existence of morphotropic phase boundary (MPB) and domain orientation. The asymmetry in the strain loops tells about the ferroelectric switching of domains after poling. The minimum value of Ti off-center displacement at 60° tells about the preferential orientation of domains after poling. XANES thereby demonstrates the quantitative and qualitative analysis of domain orientation and Ti off-center displacement in ferroelectric ceramics.

Magnetoelectric composites of lead-free piezoelectrics and yttrium iron garnet: interfacial reactions and functional properties

A wide range of magnetoelectric composites has been prepared: (100 − x) wt% FE + x wt% YIG (x = 30–70 in steps of 10 wt%), where YIG is yttrium iron garnet and FE is a lead-free ferroelectric material reported in the literature, namely lithium sodium potassium niobate ([Li0.06(Na0.52K0.48)]1.04NbO3, KLNN), modified sodium bismuth titanate ([96 mol.% Bi0.5(Na0.84K0.16)0.5TiO3 + 4 mol.% SrTiO3 + 0.2 wt% La2O3], BNT) or barium calcium zirconate titanate (Ba0.85Ca0.15Ti0.9Zr0.1O3, BCZT). The interfacial reactions and dielectric, piezoelectric, magnetic and magnetoelectric behaviors of the composites have been studied. The high-temperature calcination was found to yield the fergusonite-type impurity phase YNbO4 in KLNN-containing composites and the pyrochlore-like phase Y2Ti2O7 in BNT-containing ones. The BCZT-containing samples remain the only phase-pure materials after heat treatment. As a result, among the materials studied, the samples of (100 − x) wt% BCZT + x wt% YIG show the best magnetoelectric coupling coefficient ΔE/ΔH that reaches ~ 5 mV/(cm Oe) with x = 40. Despite showing significant piezoelectric response, the KLNN-containing ceramics exhibit ΔE/ΔH of 1.2 mV/(cm Oe) or less. The composites containing BNT show weak piezoelectric and almost zero ME response (ΔE/ΔH does not exceed 0.2 mV/(cm Oe)) due to the decomposition of ferroelectric phase caused by high-temperature interfacial reactions. The BCZT-containing composites appeared to be magnetically softer than KLNN-containing materials and magnetically harder than BNT-containing ones.

Effect of Porosity on Energy Harvesting Performance of 0.5Ba(Ca0.8Zr0.2)O3 − 0.5(Ba0.7Ca0.3)TiO3 Ceramics: A Numerical Study

Finite element analysis is conducted on a barium calcium zirconate titanate (BCZT) material to investigate its energy harvesting performance at different porosities. Porosities are gradually increased to 25% in steps of 5. BCZT piezoceramics attached to a host cantilever beam in unimorph configuration and subjected to base vibration are considered for the present study. Both and modes are considered. Power is harvested using a load resistance optimized with the structure's natural frequency of vibration. Up to a certain porosity level, an increase in voltage and power is observed in the system. An increment in voltage by ≈95% in mode and ≈119% in mode is observed at 10% porosity. Power increased by 50% in mode and by 53% in mode at 5% porosity compared with the nonporous material.

Angle Dependent Synchrotron X-Ray Absorption Spectroscopic Structural Studies on Ba <sub>0.85</sub>Ca <sub>0.15</sub>Zr <sub>0.1</sub>Ti <sub>0.9</sub>O <sub>3</sub> Ferroelectric Ceramics

Synchrotron x-ray absorption near edge structure (XANES) technique was employed to investigate the local structure, domain orientation and Ti off-center displacement in unpoled and poled barium calcium zirconate titanate (BCZT) ceramics. The domain orientation of a poled sample was detected by the angular periodicity of intensities of XANES while that of an unpoled sample did not. The angular periodicity of the intensities is related to the domain orientations through the x-ray polarization tensor. XANES is thereby demonstrated as a quantitative and quantitative technique that can measure domain switching distributions in ferroelectric ceramics.

Dielectric and piezoelectric properties of porous lead-free 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca 0.3)TiO3 ceramics

Porous barium calcium zirconate titanate 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) lead-free ferroelectric ceramics were fabricated via a burnt polymer spheres (BURPS) technique by introducing corn starch as the pore-forming agent. The effect of porosity on the microstructure, dielectric, and piezoelectric properties of the porous materials were investigated. An increase in porosity volume fraction from 10% to 25% resulted in an increase in the hydrostatic charge coefficient (dh), which was 140 to 560% higher than that of the dense BCZT material. An increase in porosity fraction from 10% to 25% also lead to a decrease in relative permittivity that was 16.7% to 60.4% lower than the dense material. These two changes in properties provided a significant enhancement of the hydrostatic figure of merit (dh∙gh) for the porous ceramic; for example the dh∙gh of the 25 vol.% porous BCZT ceramic was 158 times more than the dense ceramic and demonstrates the potential of porous lead-free ferroelectrics for piezoelectric transducer devices. Reasons for the significant enhancement in piezoelectric performance of the porous ceramics are discussed.

Characterization of Phase Evolution, Microstructure and Electrical Properties of Sol-Gel Auto-Combustion Derived BCZT Ceramics.

This work aims to study the effect of sintering temperature on properties of barium calcium zirconate titanate (BCZT) ceramics. The BCZT is a Pb-free material that shows excellent piezoelectric properties. In this study, BCZT ceramics were prepared from BCZT powders synthesized from barium nitrate, calcium nitrate, zirconium (IV) oxynitrate hydrate, titanium (IV) butoxide and citric acid precursors by the sol-gel auto-combustion method. The BCZT powder was calcined at the temperature ranging from 700 to 1000 °C. Green bodies were sintered at various temperatures (1200-1450 °C). The X-ray diffraction patterns showed only non-crystalline phase of as-burnt powder. For the calcined powders, XRD patterns showed that the amount of crystalline, perovskite phase increased with increasing calcination temperature. The crystalline particles have a spherical shape and the size in the range of 25-35 nm. For the BCZT ceramics sintered at 1200-1300 °C, the density tended to increase with increasing sintering temperature. Very high bulk densities of 5.62-5.63 g/cm3 (which were higher than those of the ceramics synthesized by the wet-chemical method) were achieved at the sintering temperature of 1400-1450 °C. Ceramics produced at these temperatures possessed fully-developed microstructures, very good dielectric properties as well as high response of polarization and strain to applied electric field.