Barium Zirconate Titanate Ceramics Research Articles

Understanding the impact of gadolinium substitution on the impedance and conduction mechanism of barium zirconium titanate ceramics

Understanding the impact of gadolinium substitution on the impedance and conduction mechanism of barium zirconium titanate ceramics

Effect of A-site cobalt doping on the structural, micro-structural and dielectric properties of (Ba1-xCox)(Ti0.95Zr0.05)O3 lead-free ceramics

Cobalt-doped barium zirconate titanate ceramics with (Ba1-xCox)(Ti0.95Zr0.05)O3 with (x = 0, 2.5, 5, 7.5 and 10 %) were synthesized by sol-gel process. The effects of Ba/Co ratio on structural, micro-structure properties and dielectric response were investigated by varying the value of x. X-ray diffraction analysis and the Rietveld refinement method revealed that the ceramics have a single phase with a tetragonal structure of the P4mm space group. The scanning electron microscope (SEM) was used to examine the texture, morphology and microstructure of the (Ba1-xCox)(Ti0.95Zr0.05)O3 ceramics. The analysis showed a decrease in average grain size as the concentration of Co2+ ions in the crystal structure increased. A study of the impedance spectroscopy of the dielectric measurements was carried out in a temperature range from room temperature to 200 °C, and revealed that the ferroelectric to paraelectric phase transition temperature decreases proportionally with increasing cobalt concentration, confirming the incorporation of Co2+ and highlighting its influence on the Curie temperature (Tc), the value of the permittivity (εr) and dielectric losses (tanδ). The Curie-Weiss law was used to study the nature of the transition, revealing that diffusivity increases in correlation with the Co2+ ion concentration.

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.

Effect of B-site disorder on the electrical properties of Barium Zirconium Titanate Ceramics composites

Effect of B-site disorder on the electrical properties of Barium Zirconium Titanate Ceramics composites

The dielectric properties and relaxor behavior of gadolinium oxide modified barium zirconate titanate ceramics for Y5V capacitor applications

The dielectric properties and relaxor behavior of gadolinium oxide modified barium zirconate titanate ceramics for Y5V capacitor applications

Modulation of polar dynamics with oxygen vacancies in Zn doped BaZr0.1Ti0.9O3

Zinc modified barium zirconium titanate ceramics have been fabricated by the solid-state reaction method. Crystallographic analysis shows that the ceramics exhibit tetragonal crystal structure with P4mm symmetry. The polar behavior of Zn doped BaZr0.1Ti0.9O3 [BZT] differs from the pure BZT compound, as observed from ferroelectric analysis. As a result of doping, the P-E loops become pinched and linear in the low field region as well as P-E loop characteristics transformed from single hysteresis to double hysteresis behavior. Double hysteresis behavior emerging in BZT ferroelectrics validates the leading characteristic of defective dipoles. The defect dipoles provide restoring force to the spontaneous dipoles and ease the recovery of domain towards its original orientation. To validate the role of defects dipoles in the synthesized ceramics, we performed P-E hysteresis measurement under field cooling protocol. P-E loops of field cooled doped-ceramics transformed into single hysteresis curve and shifts on field scale, which further confirms that the double hysteresis feature is associated with defects dipoles rather than antiferroelectric ordering. The normalized entropy curves, ΔS(E,T,x)/ΔSmax(E,TC,x), for x = 0–6%, follow the scheme of master curve with two reference temperatures and consistent with second-order phase transition theory. The dielectric spectroscopy and Arrott plot approach collectively reveal that Zn doping causes sharpening of Landau free energy profiles and doping increases the depth of double-well potential and lowers the polar dynamics. The room temperature energy storage efficiency (η∼83,x=6%) of BZT is significantly modified. Our study reveals that the interplay between ferroelectric dipoles and point defects opens a novel route toward the realization of efficient energy storage performance.

Effects of scandium oxide on domain structure, dielectric and ferroelectric properties of barium zirconate titanate ceramics

The Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ferroelectric ceramics were fabricated by the conventional solid state reaction method. The influences of Sc2O3 on their microstructure, especially domain structure, dielectric and ferroelectric properties were investigated by X-ray diffractometer, scanning electron microscope, LCR measurement system and ferroelectric tester. The Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ceramics are tetragonal perovskites with no impurity phases. The average grain size of Ba(Zr0.1Ti0.9)O3 ceramics decreases from ~40 µm to ~5 µm as the Sc2O3 content increases. Both the 90° ferroelectric domains and the 180° ones exist in the 0.2 mol% Sc2O3 doped Ba(Zr0.1Ti0.9)O3 ceramics with an average grain size of ~26 µm. The ferroelectric -paraelectric phase transition temperature and the dielectric permittivity maximum of Ba(Zr0.1Ti0.9)O3 ceramics decrease with increasing Sc2O3 doping content, while the temperature stability of relative dielectric constant is improved effectively after Sc2O3 modification in BZT ceramics. The remnant polarization and the coercive field of BZT ceramics decrease in Sc2O3 highly doped BZT ceramics as the Sc2O3 content increases.

Role of O 2p-Ti 3d orbital hybridization in dielectric and ferroelectric properties of barium zirconate titanate ceramics

Barium zirconate titanate (BaZryTi1-yO3) ceramics for y = 0.10, 0.15 and 0.20 were synthesized using conventional solid-state method to study the effect of O 2p-Ti 3d orbital hybridization on dielectric and ferroelectric properties. X-ray diffraction, transmission electron microscopy and Rietveld refinement show structural phase transition from tetragonal P4mm to cubic Pm3¯m with increasing Zr concentration. Dielectric permittivity and Raman spectra show enhanced relaxor behavior which is attributed to decreased O 2p-Ti 3d orbital hybridization as Zr doping increased. Lattice distortion due to decreased O 2p-Ti 3d orbital hybridization induced by Zr doping caused lattice strain mismatch contributing to enhancement of dielectric permittivity. Reduced ferroelectric instability due to decreased Ti-O covalency with increasing Zr significantly reduced Pr values. Temperature dependent P-E loops shows increased Wrec and η implying no energy dissipation and good thermal stability of BZT perovskites even at elevated temperatures which is beneficial for energy storage applications.

Direct measurement of enhanced electrocaloric effect in Mn2+ doped lead-free Ba(ZrTi)O3 ceramics

The manganese doped barium zirconate titanate ceramics (Ba(ZrxMnyTi1-x-y)O3-BZMT) ceramics with x = 0.15, 0.20 and y = 0, 0.0025, 0.0050, 0.0075, 0.0100, 0.0250, 0.0500 were prepared using an oxide reaction approach. The adiabatic temperature change was measured directly. Results revealed that by adjusting the nonequivalent Mn2+ ionic concentration within 0.25–0.75%, desired dielectric performances with high permittivities and lower losses were obtained. The polarization was increased with the doping content of Mn2+ ions. The largest electrocaloric temperature change obtained is 2.35 K for Ba(Zr0.15Mn0.0025Ti0.8475)O3 ceramics at 62 °C, and a broad temperature range of ∼40 °C was accompanied.

Dielectric and ferroelectric properties of barium zirconate titanate ceramics prepared by ceramic method

Barium zirconate titanate BaZr1-xTixO2 where x = (0,0.1,0.2,0.3 and 0.4) were prepared by conventional ceramic method. From XRD, it was found that the peak intensity of the samples increased by increasing Ti content, indicating the increase of crystalline state and the percentage of tetragonal phase. From SEM micrograph the porosity increases as grain size decrease which indicates that the backing of grain was destructed by the addition of Ti ions. The TEM images showed that nano crystallites are agglomerated in most position of the images with an average particle size ranged from 20 to 75.5 nm. It is observed that the samples DC resistivity slightly decrease with increasing Ti content, whereas dielectric constant and dielectric loss increase by increasing Ti constant. The polarization decreases near Curie temperature and reach zero value and the relation between electric field and polarization becomes linear without hysteresis.

Microstructure and transport properties of multiwall carbon nanotube-reinforced barium zirconium titanate ceramics

The influence of multiwall carbon nanotubes (MWCNTs) reinforced on microstructures and their transport properties on pure and cerium-substituted barium zirconium titanate (BZT) ceramics are reported in this study. The MWCNTs were prepared by a low-temperature sonochemical/hydrothermal method using dichloromethane as a carbon source. These MWCNTs were mixed with the as-prepared ceramic powders before heat treatment to obtain a reinforced product. The scanning electron micrographs reveal the successful incorporation of carbon nanotubes in BZT ceramics. The temperature-dependent direct current (dc)-resistivity was less for MWCNT-reinforced ceramics in contrast to that of pure ceramics. The decrease in the dc resistivity was due to the superior electrical behaviour of MWCNTs, which act as a connector between ceramic grains. The Seebeck coefficient of cerium-substituted-BZT improved after reinforcing the MWCNTs.

Direct Measurement of Enhanced Electrocaloric Effect in Mn <sup>2+</sup> Doped Lead-Free Ba(ZrTi)O <sub>3</sub> Ceramics

The manganese doped barium zirconate titanate ceramics (Ba(ZrxMnyTi1-x-y)O3-BZMT) ceramics with x= 0.15, 0.20 and y=0, 0.0025, 0.0050, 0.0075, 0.0100, 0.0250, 0.0500 were prepared using an oxide reaction approach. The adiabatic temperature change was measured directly. Results revealed that by adjusting the nonequivalent Mn2+ ionic concentration within 0.25% to 0.75%, desired dielectric performances with high permittivities and lower losses were obtained. The polarization was increased with the doping content of Mn2+ ions. The largest electrocaloric temperature change obtained is 2.35 K for Ba(Zr0.15Mn0.0025Ti0.8475)O3 ceramics at 62°C, and a broad temperature range of ~ 40°C was accompanied.

Enhanced dielectric strength and energy storage density in BaTi0.7Zr0.3O3 ceramics via spark plasma sintering

Barium zirconate titanate (BaTi0.7Zr0.3O3) ceramics were prepared via spark plasma sintering (SPS) and conventional solid-state sintering (CS). Both samples exhibited single phase nature as confirmed from the X-ray diffraction analysis. Compared with CS sample, more homogeneous microstructure with smaller grain size was observed in the SPS sample, which greatly improved the dielectric strength of BaTi0.7Zr0.3O3 ceramics from 40 (CS) to 170 kV/cm (SPS). Although the polarization of SPS sample was lower than that of CS sample under the same applied electric field, the maximum energy storage density was improved to 0.51 J/cm3, which was about 4.5 times higher than that of the CS sample (0.12 J/cm3). Moreover, finite element simulation on the local dielectric field distribution was carried out, and the effects of microstructure on the dielectric strength were further confirmed.

Investigation on structural and electrical properties of BZT ceramics synthesized at low temperature

Due to environmental concerns, lead free ceramics such as KNN- NBT and BT have growing interest in applications such as actuators and sensors. Among them Barium Zirconate Titanate (BZT) has become most attractive because it is derived from two perovskite lattice i.e. Barium Titanate (BaTiO3) and Barium Zirconate (BaZrO3). It has been reported that Zirconium substitution in titanium lattice enhances the material properties. In the present paper BZT was prepared using solid state route. By adding a mixture of Li2CO3 as a sintering aid, the sample could be sintered at 1150 °C having around 94% of the theoretical density. Prepared samples were then subjected to XRD analysis. X-ray diffraction revealed the formation of single phase material. It is observed that the electrical properties of such low-temperature sintered samples are comparable with BZT samples prepared via conventional sintering at a high temperature. It is also observed that the curie temperature shift towards room temperature for a samples sintered at low temperature.

Improved dielectric and ferroelectric properties of Mn doped barium zirconium titanate (BZT) ceramics for energy storage applications

Lead free Mn doped barium zirconium titanate ceramic of composition BaZr0.045 (MnxTi1-x)0.955O3 (x = 0.00, 0.01, 0.02) were prepared by solid state reaction method. Tetragonal perovskite structure was confirmed by Rietveld refinement of X-ray diffraction pattern. Analysis of Scanning electron microscope (SEM) micrographs revealed that addition of Mn up to a certain limit accelerates grain growth of BZT ceramic. Static dielectric constant was successfully extended up to high frequencies with an appreciable decrease in dielectric loss about 70% for Mn doped BZT ceramics. The experimental data fitted with Curie Weiss Law and Power Law confirmed first order transition and diffusive behavior of the investigated system. The shifting of Curie temperature (Tc) from 387 K to 402 K indicated tendency for sustained ferroelectricity in doped BZMT ceramics. High value of percentage temperature coefficient of capacitance TCC >10% near Tc was observed for all the compositions and increases with Mn content in pure BZT. At room temperature, BZT modified ceramic corresponding to x = 0.01 composition shows better values of remnant polarization (Pr = 5.718 μC/cm2), saturation polarization (Ps = 14.410 μC/cm2), low coercive field (Ec = 0.612 kV/cm), and highest value of Pr/Ps = 0.396.

Direct Measurement of Large Electrocaloric Effect in Ba(ZrxTi1-x)O3 Ceramics.

Barium zirconate titanate (BZT) (Ba(ZrxTi1-x)O3) ceramics with Zr4+ contents of x = 5, 10, 15, 20, 25, and 30 mol % were prepared using a solid-state reaction approach. The microstructures, morphologies, and electric properties were characterized using X-ray diffraction, scanning electron microscopy, and impedance analysis methods, respectively. The dielectric analyses indicate that the BZT bulk ceramics show characteristics of phase transition from a normal ferroelectric to a relaxor ferroelectric with the increasing Zr4+ ionic content. The electrocaloric effect adiabatic temperature change decreases with the increasing Zr4+ content. The highest adiabatic temperature change obtained is 2.4 K for BZT ceramics with a 5 mol % of Zr4+ ionic content.

Influence of CoO Nanoparticles on Properties of Barium Zirconium Titanate Ceramics

Composites of Ba(Zr0.07Ti0.93)O3 ceramic and CoO nanoparticles (at 1.0 vol.% to 3.0 vol.%) have been fabricated to investigate the effects of the CoO nanoparticles on the properties of the composites. X-ray diffraction data revealed that the modified samples contained Ba(Zr0.07Ti0.93)O3 and CoO phases. Addition of CoO nanoparticles improved the magnetic behavior and resulted in slight changes in ferroelectric properties. The composites showed a magnetoelectric effect in which the negative value of the magnetocapacitance increased with increasing CoO concentration. Examination of the dielectric spectra showed that the two phase-transition temperatures as observed for unmodified Ba(Zr0.07Ti0.93)O3 merged into a single phase-transition temperature for the composite samples. The composite samples also showed broad relative permittivity versus temperature (er–T) curves with frequency dispersion. This dielectric behavior can be explained in terms of the Maxwell–Wagner mechanism. In addition, the Vickers hardness (Hv) value of the samples increased with increasing CoO content.

Influence of Cd doping on the electro-strain of barium zirconate titanate ceramics

Cadmium doped barium zirconate titanate (Ba1−xCdx)(Zr0.13Ti0.87)O3 (BCDZT) ferroelectric ceramic compositions with x=0, 0.02, 0.04 and 0.06 have been prepared by solid state reaction method. X-ray diffraction studies reveal a pseudocubic structure. For increasing Cd content, the bulk ceramic micro-structure reveals an increasing grain size and density. Variations in the dielectric, piezoelectric and unipolar electric field induced strain characteristics are discussed. Increasing Cd content reduces the coercive field, increases the remnant polarization and does not affect the ferroelectric-paraelectric phase transition temperature (~60°C). An optimum Cd content x=0.06 produces highly resistive ceramics with low dielectric loss (tanδ=0.019), and a maximum value of piezoelectric charge constant d33=114 pC/N and unipolar electro-strain of ~0.07%.

Structural, dielectric, and impedance study of ZnO-doped barium zirconium titanate (BZT) ceramics

Polycrystalline lead-free BaZr0.15Ti0.85O3 ceramics doped with ZnO (0 ≤ x ≤ 2 wt%) were produced via mixed oxide solid-state reaction method. X-ray diffraction confirmed the presence of a single phase having tetragonal symmetry and having space group P4 mm. Scanning electron microscopy confirmed an increase in the density of microstructure and enlargement of grains with increase in ZnO concentration. Complex impedance spectroscopy revealed non-Debye type relaxation phenomenon. It was observed that an increase in the resistance of grain boundaries and decrease in that of grain interior (bulk) occurred with an increase in temperature. Relaxation time decreased with increase in temperature for both grain boundaries and grain interior. Understandings obtained from this work might be helpful in engineering the microstructure of BZT-based ceramics for useful applications.

Preparation and Electric Properties of Barium Zirconium Titanate Ceramic

The relaxor behavior of barium zirconium titanate ceramics BaZr0.35Ti0.65O3 prepared by a conventional sintering process was investigated. The synthesized material was determined by an X-ray diffraction and scanning electron microscopy. Based on performed studies, the BaZr0.35Ti0.65O3 ceramic material has been identified as canonical relaxor, related to the Ti-rich polar regions. The freezing temperature Tf and activation energy Ea are calculated from the Vogel-Fulcher relationship.