Pure BCZT Research Articles

Effects of CuO additive on properties of high-performance (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 piezoceramics obtained by vat photopolymerization

Lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCZT) piezoelectric ceramics are ideal materials for the preparation of piezoelectric ceramic devices. However, pure BCZT ceramics have the problems of high sintering temperature and unsatisfactory Curie temperature. Besides, piezoelectric ceramic devices with complex structures are difficult to fabricate with conventional processing methods. In this paper, we prepared BCZT ceramics with CuO additions of 0, 0.5, 1.0, 1.5, and 2.0 mol% based on vat photopolymerization, and investigated effects of CuO additive on their various properties. The appropriate addition of CuO greatly improved the piezoelectric properties and lowered the sintering temperature by 100 °C. With increasing CuO content, it was found that the phase composition shifted from an orthogonal phase to the coexistence of orthogonal and tetragonal phases. BCZT-1.5 mol%CuO sintered at 1400 °C exhibited the best performance: d33 = 525 pC/N，g33 = 13.7 × 10−3 Vm/N，εr = 4323，tan δ = 0.012，Pr = 14.66 μC/cm2，Ec = 2.42 kV/cm. In addition, when the energy harvesting performance of BCZT-1.5 mol%CuO with complex structures prepared by vat photopolymerization was tested, the short circuit current (Isc) and open circuit voltage (Voc) of BCZT-1.5 mol% CuO ceramics were ∼13.0 pA and ∼11.0 mV, respectively, which exhibited better energy harvesting capability than the pure BCZT ceramics. These results suggest that the performance of BCZT ceramics can be significantly enhanced with CuO additive and verify the feasibility of vat photopolymerization forming high-performance piezoelectric ceramics with complex structures.

First-Principles Study on the Mechanical Properties of Gd-Doped BCZT Ceramics

Due to their remarkable piezoelectric characteristics, (BaCa)(ZrTi)O3 (BCZT) ceramics exhibit vast potential for being employed in cutting-edge electromechanical apparatus. Extensive experimental studies have been conducted to better meet the practical needs of BCZT-based materials, focusing on their mechanical performance. However, there is a serious lack of research on the theoretical computational aspects. Here, first-principles calculations were utilized to evaluate the mechanical properties of BCZT-xGd ceramics. The structural models were established using the virtual crystal approximation (VCA) method. The investigated compounds demonstrate structural and mechanical strength, as evidenced by their negative formation energies and adherence to the Born stability criteria. Compared to pure BCZT, the substitution of Gd leads to a significant enhancement in the system’s elasticity and stiffness. The BCZT-0.05Gd with B-site doping demonstrates the highest level of Vicker’s hardness (HV), with the noteworthy observation that the inclusion of Gd concomitantly augments its machinability performance. Upon the incorporation of the Gd element, the anisotropic elasticity in the systems gradually transitions into isotropic elasticity, which favors a more uniform stress distribution and consequently reduces sensitivity to the formation and propagation of microcracks. These results indicate that BCZT-xGd exhibits potential for application in electromechanical systems.

Electrical properties of Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics with TiO2 addition

The crystal structure, microstructure, dielectric properties and energy storage properties of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics with various TiO2 (0%, 1%, 8%, 40%, 50%, 60%) addition ceramics were discussed. Although the perovskite structure remained in samples with low content of TiO2, the secondary phase Ba2Ti5.5O13 appeared in samples with high TiO2 content. According to SEM results, the addition of TiO2 resulted in a significant decrease in the average grain size. With the addition of TiO2, the phase transition temperature, corresponding to Curie temperature (Tc) of BCZT ceramics shifts to lower temperature. Compared with the pure BCZT ceramic, the higher impedance and slimmer hysteresis loops were realized in ceramics with high TiO2 content. The relatively large energy storage density (Wrec ∼ 0.52 J/cm3) together with energy storage efficiency (η ∼ 74.84%) were achieved in ceramic with 40% TiO2 content. When the concentration of TiO2 further increases, the energy storage efficiency increased, but the energy storage density declined. The present research provides a method to improve the energy storage performance of BCZT ceramics.

Structural, dielectric and ferroelectric properties of Cu2+- and Cu2+/Bi3+-doped BCZT lead-free ceramics: a comparative study

Perovskite-type Ba0.98Ca0.02Zr0.02Ti0.98O3 (BCZT), Ba0.98Ca0.02Zr0.02Ti0.976Cu0.008O3 (BCZTC) and Ba0.9725Bi0.005Ca0.02Zr0.02Ti0.976Cu0.008O3 (BCZTCB) lead-free ceramics were synthesised via solid-state reaction method at a sintering temperature of 1380 °C. Effects of CuO and Bi2O3/CuO doping on structural, microstructural, dielectric and ferroelectric properties were investigated systematically. X-ray diffraction technique confirmed the existence of pure perovskite phase with the tetragonal structure in pure and in the doped BCZT ceramics at room temperature. The dielectric analysis demonstrated two anomalies around 24 °C and 126 °C for BCZT, which were identified as orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC) phase transition temperature, respectively. The TO-T temperature shifted to below 16 °C, while the TC increased to 132 °C for the BCZTCB sample. The physical mechanisms of the conduction processes were investigated through impedance spectroscopy, and the values of resistance, conductivity and activation energies associated with the grain and grain boundaries were evaluated. The activation energy was determined to be higher for doped samples than for pure BCZT. Further, the dopant-dependent ferroelectric nature of the ceramic samples was evidenced by the analysis of characteristic hysteresis loop, and a value of remnant polarization (Pr = 4.59 μC/cm2) was obtained for the BCZTCB ceramic sample. Furthermore, the d33 value, which was 54 pC/N for pure BCZT, was determined to be 140 pC/N and 64 pC/N for BCZTC and BCZTCB, respectively.

Modulation in polymer properties in PVDF/BCZT composites with ceramic content and their energy density capabilities

AbstractThe lead‐free 0.5((Ba0.7Ca0.3)TiO3)‐0.5(Ba(Zr0.2Ti0.8))O3(BCZT) piezoceramics were synthesized using sol‐gel method. The Rietveld analysis of X‐ray diffraction (XRD) data and differential scanning calorimetry (DSC) studies of as‐synthesized BCZT powder suggests the co‐existence of ferroelectric orthorhombic (O) and tetragonal (T) phases at room temperature (RT). The value of curie temperature (TT‐C) as depicted from DSC and dielectric studies was found to be ≈ 110°C. The BCZT ceramic particles were dispersed in the polyvinylidene fluoride (PVDF) matrix, an electroactive polymer with great ferro/piezoelectric response in its distinct β and γ phases, to form ferroelectric ceramic‐polymer composites for their applications in flexible energy storage capacitors. The present work reports the Fourier‐transform infrared spectroscopy (FTIR), XRD, dielectric, ferroelectric, and energy density properties of PVDF/BCZT composite films having different wt% of BCZT content fabricated by the solution‐cast technique. The FTIR and XRD studies depict the γ‐PVDF and pure BCZT phases in composite films. The dielectric studies estimated the relative permittivity (εr) of a composite film with 50 wt% of BCZT content to be ≈ 31 (at 120 Hz) which was about three times as compared with that of pure PVDF. The dielectric loss (tan δ) was maximum ≈ 0.15 (at 120 Hz) for 50 wt% BCZT composition. The ferroelectric studies and energy storage calculations showed that the value of remnant polarization (Pr), coercive field (Ec) and energy storage density (W) attain the maximum value of 0.63 μC/cm2, 21.20 kV/cm, and 70.46 mJ/cm3, respectively for the film sample having 40 wt% BCZT content. The maximum energy storage efficiency, η (%) is calculated to be ≈ 60 for 50 wt% BCZT composition. The results indicated that the incorporation of BCZT particles in the PVDF matrix improved the overall polarization (polar and interfacial) which enhance the electric properties of composite films. The ferroelectric studies with temperature revealed the PVDF/BCZT composition‐dependent polymer or ceramic dominance in the behavior of composite films. With the maximum value of relative permittivity (εr) and energy storage efficiency (η), the PVDF/BCZT composition with 50 wt% of BCZT content has been optimized for applications in flexible energy storage capacitors.

Enhanced energy storage properties in Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics with glass additives

The Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics added with Bi2O3–B2O3–SiO2 glass were synthesized by the sol-gel method, and the effect on their microstructural, dielectric, energy storage properties has been discussed. The SEM results demonstrate that the average grain size decreases obviously with reducing glass additive, which is enriched at the grain boundary. Owing to the addition of glass additive, sintering temperature decreases significantly. Moreover, the glass additives broaden the dielectric peak and the Curie temperature shifts toward lower temperature. The ceramic with glass additive shows better impedance properties than that of pure BCZT ceramics. In addition, the coercive field and remnant polarization of hysteresis loop were greatly decreased by introducing glass additives in BCZT ceramics. Notably, the sample with 5% glass additive shows the highest energy storage density (2.12 J/cm3) and the largest storage efficiency (90.5%) at 330 kV/cm electric field. These findings provide a potential pathway to enhance energy storage properties of BCZT ceramics in order to promote its energy storage application in practice.

Preparation and characterization of (Ba0.85Ca0.15)(Zr0.1Ti0.9)TiO3(BCZT)/Bi2O3 composites as efficient visible-light-responsive photocatalysts

The heterojunction composites (Ba0.85Ca0.15)(Zr0.1Ti0.9)TiO3(BCZT)/Bi2O3 with different weight ratios (75:25, 50:50 and 25:75) were successfully synthesized by solid-state route. As-synthesized composite powders were characterized by XRD, FESEM, EDX, UV–visible and photoluminescence spectroscopy. Photocatalytic activity evaluation was carried out by the degradation of rhodamine B (RhB) under UV and visible light exposure. The results show that the heterojunction composites BCZT/Bi2O3 display better photocatalytic activity than pure BCZT or Bi2O3. Among all the heterojunction composites, BCZT/Bi2O3 (50:50) composite exhibits a lower recombination rate of electron–hole pair and shows the highest photocatalytic activity. The rate constant of BCZT/Bi2O3 (50:50) composite for RhB degradation is 15.4 and 2.1 times higher than those of pure BCZT and Bi2O3 under visible light irradiation, respectively. Finally, a possible mechanism for enhanced charge separation and photodegradation is proposed.

Multiferroic properties of lead-free 0.2(Ni0.8 Zn0.2Fe2O4)-0.8(Ba0.85Ca0.15Zr0.1Ti0.9O3) magnetoelectric composite

In this work the structural, electric and magnetic characteristics of 0.2(Ni0.8 Zn0.2Fe2O4 (NZF))-0.8 (Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT)) multiferroic composite is investigated. The constituent phases were synthesized by sol-gel process, and mixed in an appropriate ratio to form the composite. The XRD data and Rietveld refinement confirm that the composite exists in cubic+tetragonal+orthorhombic mixed phases. The P-E loop of the composite shows a finite loop opening with a decrease in the polarization compared to the pure BCZT. The M-H loops show a saturated loop at an applied field ∼ 1 kOe and the values of magnetization decreased nearly by four orders, compared to the pure NZF.

The effect of sintering temperature on the microstructure and functional properties of BCZT-xCeO2 lead free ceramics

We report (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 + x wt.% CeO2 lead free piezoelectric ceramics fabricated by conventional solid-state reaction routes. The phase structure, microstructure and functional properties have been systematically investigated. The morphotropic phase boundary was investigated in the range of x = 0 - 0.1%. A comparative study of their functional properties as a function of sintering temperature is presented. The study shows the important role of sintering temperature and grain size on the functional properties of these ceramics. Enhanced properties are observed for x = 0.07% at a sintering temperature 200 °C lower than for pure BCZT, in which, d33 = 507 ± 20 pC/N, kp = 51.8%, εr = 4091 ± 100, tan δ = 0.02, Pr = 16.32 μm/cm2, EC = 2.13 kV/cm and TC = 104.6 °C indicating that these ceramics are promising lead-free substitutes for the widely used lead-based ceramics.

Effects of Tb doping on structural and electrical properties of 47(Ba0.7Ca0.3)TiO3–0.53Ba(Zr0.2Ti0.8)O3 thin films at various annealing temperature by pulsed laser deposition

The ceramic thin films of 47(Ba0.7Ca0.3)TiO3–0.53Ba(Zr0.2Ti0.8)O3 (BCZT) + x (x = 0.2, 0.3, 0.4 and 0.5)mol% Tb were grown on Pt(111)/Si substrates with various annealing temperature by pulsed laser deposition. The XRD spectra confirm that Tb element can enhance the (l10) and (111) orientations in ceramic films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images show that Tb-doping can increase particle size effectively. The surface of Tb-doped film annealed at 800℃ is uniform and crack-free, and the average particle size and mean square roughness (RMS) are about 280nm and 4.4nm, respectively. Comparing with pure BCZT, the residual polarization (Pr) of 0.4mol% Tb-doped film annealed at 800℃ increase from 3.6 to 9.8 μC/cm2. Moreover, the leakage current density value of Tb doped films are one order of magnitude (5.33 × 10−9−1.97 × 10−8A/cm2 under 100kV/cm) smaller than those of pure BCZT films (1.02 × 10−7A/cm2).

Multiferroic properties of (1-x)BCZT-xLCMO laminated composites

The electrical, ferromagnetic and magnetoelectric properties of the (1-x) Ba0.85Ca0.15Zr0.10Ti0.90O3-xLa0.67Ca0.33MnO3 [(1-x)BCZT-xLCMO] laminated composites were investigated. The ferroelectric and ferromagnetic characteristics demonstrated that the laminated composites are multiferroic in nature. Our results indicated that the performances of the laminated composites showed strong dependence on the thickness ratio between the ferroelectric BCZT layer and ferromagnetic LCMO layer. Enhanced dielectric properties were obtained for the laminated composites compared with that of the pure BCZT. The piezoelectric coefficient (d33) and coercive electric fields (EC) of the laminated composites declined with the increasing LCMO nonferroelectric layer, while the saturated magnetization (MS) increased and the coercive magnetic field (MC) kept constant. The 0.3BCZT-0.7LCMO composites obtained the largest magnetoelectric coefficient of αE31 = 1.66mV/cm·Oe.

Diffuse characteristics and piezoelectric properties of Tb-doped BCZT ceramics with CaCl2 as sintering aid

Lead-free ceramics 47(Ba0.7Ca0.3)TiO3–0.53Ba(Zr0.2Ti0.8)O3 (BCZT) + 0.2mol% Tb and xCaCl2 (x = 0.1,0.2 and 0.3wt%) were prepared at different temperatures (1300, 1350 and 1410℃) by solid-state reaction method. The experimental results reveal that dopants can effectively promote the growth of grain at relatively low sintering temperature and CaCl2 as the well sintering aid can produce a pronounced liquid phase to fill the gap between grains sintered at 1410℃ with 0.2wt%. Relative densities and piezoelectric properties of samples can be improved by the introduction of Tb and CaCl2. Comparing with pure BCZT, the residual polarization (Pr) and piezoelectric coefficient (d33*) of ceramics increase from 8.2 to 11.4μC/cm2 and 568–720pm/V with 0.2mol% Tb and 0.2wt% CaCl2 doped. The enhanced properties of samples may be related to the appearance of liquid phase which can increase relative densities of ceramics to 96% and the form of defect dipole in ceramics. Moreover, introduction of CaCl2 makes dielectric peaks (Tc) move to the high-temperature zone about 13℃ and become more and more diffuse (γ = 1.71–1.86), which may have the potential electro-caloric effect application in ferroelectrics.

Dielectric behavior and impedance spectroscopy of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics with B2O3-Al2O3-SiO2 glass-ceramics addition for enhanced energy storage

A series of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics with different contents of B2O3-Al2O3-SiO2 (BAS) glass-ceramics additive were prepared via the conventional solid-state sintering method. The microstructure, dielectric properties, ferroelectric properties and energy storage properties were systematically investigated. The results show that the BCZT and BAS glass-ceramics phases can coexist in the ceramics and the average grain size reduces obviously with increasing the content of BAS glass-ceramics. The addition of BAS glass-ceramics could enhance the breakdown strength of the ceramics obviously. Due to the relatively high dielectric constant and breakdown strength, the estimated energy storage density of the (1-x)BCZT-xBAS ceramics reaches up to 1.153 J/cm3 when x = 5%, which is improved by 5.5 times as compared with that of the pure BCZT ceramic (0.205 J/cm3).

Improved Electrical Properties of Low-Temperature Sintered Cu Doped Ba0.99Ca0.01Zr0.02Ti0.98O3 Ceramics

In this study, a series of Ba0.99Ca0.01Zr0.02Ti0.98O3-x mol.% Cu (BCZT-xCu) ceramics were fabricated with a conventional solid state reaction method. The effects of sintering temperature and doping level of Cu ions on the microstructure development and electrical properties were studied systematically. The optimal sintering temperature could be lowered by 200°C compared to pure BCZT ceramics, due to the addition of Cu. Optimized properties were obtained for BCZT-2.0 mol.% Cu ceramics sintered at 1250°C, showing improved ferroelectric properties with a high remnant polarization (P r = 8.25 μC/cm2) and a low coercive field (E c = 0.395 kV/mm). Of particular significance is that the dielectric properties were found to show high thermal stability. The dielectric constant $$ \left( {\varepsilon_{r} } \right) $$ is within the scope of 1900–2350, while the dielectric loss (tanδ) is in the range of 1.15–2.2% within a temperature range of 30–105°C. In general, the BCZT-2.0Cu ceramics mainly display the characteristic of normal ferroelectrics.

Effects of CuO additive on structure and electrical properties of low-temperature sintered Ba0.98Ca0.02Zr0.02Ti0.98O3 lead-free ceramics

Lead-free Ba0.98Ca0.02Zr0.02Ti0.98O3–xmol% (x=0–2.0) CuO ceramics (BCZT–xCu) were fabricated by the traditional solid state reaction technique, and their structure and electrical properties were studied systematically. With the introduction of Cu, the orthorhombic–tetragonal (TO–T) phase transition shifted towards lower temperature, while Curie temperature (Tc) remained at relatively high value of about 120°C. The sintering temperature was reduced by 150°C than that for pure BCZT ceramics while showing equivalent properties. 0.8mol% Cu modified ceramics showed excellent piezoelectric properties with d33=315pC/N and kp=44%. Besides these, a relatively high dielectric coefficient (εr=2280), a low dielectric loss (tanδ=1.14%), a high remnant polarization (Pr=11.6μC/cm2) and low coercive field (Ec=0.37kV/mm) were also obtained on Ba0.98Ca0.02Zr0.02Ti0.98O3–0.8mol% Cu lead-free ceramics. Moreover, the influence of sintering temperature on the microstructure development and electrical properties of BCZT–0.8mol% Cu ceramics has also been studied.