Effects of La-doping on microstructure, dielectric and piezoelectric properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics

Lead-free (Ba_0.85Ca_0.15)_1?xLa_2/3xTi_0.90Zr_0.10O₃ + 1 mol% MnO₂ ceramics have been prepared an ordinary sintering technique and the effects of La-doping on the microstructure, dielectric and piezoelectric properties of Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ were studied. All the ceramics possess a pure perovskite structure, indicating that La ions are incorporated into Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ lattices to form a lead-free solid solution. The ceramics are transformed from coexistence of orthorhombic and tetragonal phases to pseudocubic phase with the doping level of La increasing. After the doping of La, grain growth is inhibited, ferroelectric-paraelectric phase transition temperature (T _C) is decreased and the degree of diffuse phase transition is increased. The ferroelectricity of the ceramics is weakened after the addition of La. Unlike donor-doped lead zirconate titanate ceramics, the piezoelectric properties of the ceramics are degraded after the partial substitution of La³⁺ for (Ba_0.85Ca_0.15)²⁺ because of the weakness or disappearance of coexistence of orthorhombic and tetragonal phases near room temperature. The (Ba_0.85Ca_0.15)_1?xLa_2/3xTi_0.90Zr_0.10O₃ + 1 mol% MnO₂ ceramic with x = 0 exhibit the optimum piezoelectric properties: d ₃₃ = 277 pC/N and k _p = 30.3 %, respectively.     

Effect of CuO on the microstructure and electrical properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 piezoceramics

In this study, the effect of CuO content on the microstructure and electrical properties of Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ (BCZT) ceramics was systematically studied. The addition of CuO effectively results in an increase of grain sizes in BCZT ceramics. BCZT ceramics endure a lattice distortion due to the Cu²⁺ part substitution for the Ti⁴⁺ site, and a low-sintering temperature of BCTZ ceramics is induced by the addition of CuO. With increasing CuO content, the dielectric constant and the dielectric loss of BCTZ ceramics decrease, together with the decrease of the remanent polarization and the coercive field. Effects of sintering temperature and dwell time on the microstructure and electrical properties of BCZT ceramics with x = 0.5 mol% CuO were also studied, and an optimum sintering condition helps to further improve its electrical properties. BCZT ceramics with x = 0.5 mol% CuO possess optimum electrical properties: d ₃₃ ~ 403 pC/N and k _p ~ 44.6% when sintered at a low temperature of 1400 °C for 6 h. As a result, BCZT ceramics with a sintering aid of CuO are a promising candidate for the transducer and transformer applications.     

Effects of MnO2 and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics

Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ + xmol% MnO₂ lead-free ceramics have been prepared by a conventional sintering method and the effects of MnO₂ and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ lead-free ceramics have been studied. The addition of 0.25 mol% MnO₂ promotes grain growth, improves the ferroelectricity of the ceramics and strengthens ferroelectric tetragonal–ferroelectric orthorhombic phase transition near 40 °C. Because of the coexistence of tetragonal and orthorhombic phases and the combinatory effects of soft and hard doping of Mn ions, the ceramic with x = 0.25 exhibits the optimum piezoelectric properties (d ₃₃ = 306 pC/N and k _p = 42.2 %, respectively). Excess MnO₂ inhibits the grain growth and degrades the ferroelectric and piezoelectric properties of the ceramics. Sintering temperature has an important influence on the microstructure, tetragonal–orthorhombic phase transition near 40 °C, ferroelectric and piezoelectric properties of the ceramics. The increase in sintering temperature leads to large grains and more noticeable tetragonal–orthorhombic phase transition near 40 °C, enhances ferroelectricity and thus improves effectively the piezoelectricity of the ceramics. The Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ ceramic sintered at 1350 °C possesses the optimum piezoelectric constant d ₃₃ value of 373 pC/N.     

Enhanced energy storage performance of (Ba0.85Ca0.15) (Zr0.10Ti0.90) O3-based ceramics through a synergistic optimization strategy

Journal of Materials Science: Materials in Electronics - (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3 (BCZT) ceramics exhibit excellent electrical properties due to the existence of morphotropic phase boundary...     

Dielectric,ferroelectric, and piezoelectric properties of Sb2O3-modified (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free ceramics

The microstructures, phase structure, and electrical properties have been investigated for the Sb₂O₃-modified (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ lead-free piezoelectric ceramics. The grain size was strongly affected by Sb₂O₃, and the solid solutions show a single phase perovskite structure. The ceramics with x = 0.1 % exhibit enhanced electrical properties of d ₃₃ ～556 pC/N, k _p ～52 %, ε _r ～3,895, tan δ ～1.3 %, and P _r ～12.6 μC/cm² when sintered at a low temperature of ～1,350 °C. The high temperature stability of ferroelectric properties (P _r ～14.8 μC/cm²) was obtained in the temperature range from ?60 to 0 °C. And with the addition of small amount of Sb₂O₃, Curie temperature (T _c ) maintains virtually unaltered.     

Low temperature sintering and properties of lead-free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics with Ba(Cu0.5W0.5)O3 addition

The low-temperature sintering behavior of (Ba_0.85Ca_0.15)(Zr_0.10Ti_0.90)O₃ (BCZT) piezoelectric ceramics with Ba(Cu_0.5W_0.5)O₃ (BCW) addition has been investigated. The addition of 0.1 wt% BCW promotes the sinterability of BCZT ceramics owing to the generation of a liquid phase, resulting in a reduction of sintering temperature from 1,540 to 1,350 °C. The piezoelectric coefficient (d ₃₃), and the electromechanical coupling factor (kp) of the BCZT ? 0.1 wt%BCW specimen sintered at 1,350 °C were 555 pC/N and 55 %, respectively, while Curie temperature (Tc) increases from 85 to 95 °C.     

Microstructure,dielectric, and energy storage performance of (Zn1/3Nb2/3)4+ complex-ion modified (Ba0.85Ca0.15)(Zr0.10Ti0.90)O3 ceramics

In this study, (Ba_0.85Ca_0.15)(Zr_0.10Ti_0.90)_1-x(Zn_1/3Nb_2/3)_xO₃ ceramics were synthesized by conventional solid-phase methods, referred to as BCZT-xZN (x?=?0.0, 0.1, 0.2, 0.3, 0.4). The effects of adding different contents of (Zn_1/3Nb_2/3)⁴⁺ ion on the microstructure, dielectric and ferroelectric properties of BCZT ceramics were studied. Scanning electron microscopy (SEM) results showed that the average particle size of the samples was significantly reduced after the addition of (Zn_1/3Nb_2/3)⁴⁺ ion, and a second phase appeared when the addition amount was?≥?0.3. The dielectric properties show that with (Zn_1/3Nb_2/3)⁴⁺ ion replacing the B-site of BCZT ceramics, the dielectric constant decreases significantly and the Curie temperature decreases below room temperature. At the same time, we observed that the ceramic has good stability to temperature (-150 °C–200 °C) and frequency (10²–10⁶ Hz) changes. The addition of (Zn_1/3Nb_2/3)⁴⁺ ion can significantly reduce the residual polarization and improve the breakdown strength of ceramics. When x?=?0.3, The maximum energy storage density of ceramics is 0.994 J/cm³, which is about four times higher than that of pure BCZT ceramic (0.25 J/cm³). These findings fully demonstrate the great potential of BCZT ceramics in energy storage.

     

Improved energy storage and electrocaloric properties of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramic

Lead-free Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) ceramic powders were synthesized using the sol–gel method. The ceramics thickness was reduced to achieve high-energy storage and large electrocaloric effect in bulk ceramics. Dielectric, ferroelectric, energy storage, and electrocaloric properties were investigated for BCZT ceramic with 400 µm. Here, pure crystalline structure and homogenous microstructure were identified by XRD analysis and SEM measurements, respectively. The dielectric measurements revealed a maximum dielectric constant associated with ferroelectric–paraelectric phase transition. The maximum of \(\varepsilon^{\prime}_{{\text{r}}}\) was 17841, around 352 K. Furthermore, the BCZT ceramic exhibited improved energy storage and electrocaloric properties. A high recoverable energy density W_rec of 0.24 J/cm³ and a total energy density W_total of 0.27 J/cm³ with an efficiency coefficient of?~?88% at 423 K under an electric field of 55 kV/cm were obtained. Besides, The maximum value of ΔT?=?2.32 K, the electrocaloric responsivity ζ?=?0.42 K mm/kV, the refrigeration capacity RC?=?4.59 J/kg and the coefficient of performance COP?=?12.38 were achieved around 384 K under 55 kV/cm. The total energy density W_total and the temperature change ΔT were also calculated by exploiting the Landau–Ginzburg–Devonshire (LGD) theory. The theoretical results matched the experimental findings. These results suggest that the synthesized BCZT ceramic with reduced thickness could be a promising candidate for energy storage and electrocaloric applications.

     

制备工艺对(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3无铅压电陶瓷结构与性能的影响

采用液相混合与固相烧结相结合的方法制备了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃ (BCTZ) 无铅压电陶瓷, 系统研究了烧结保温时间对其相结构、介电、压电和铁电性能的影响以及电学性能随温度的变化。研究结果表明: 制备的陶瓷样品具有单一的四方钙钛矿结构。当烧结温度为1540℃时, 随着保温时间的延长, 样品晶粒尺寸变大, 居里温度(T_c)升高, 压电性能提高, 电致伸缩性能下降。当保温时间为24 h时, BCTZ陶瓷综合性能最为优异: T_c ~90℃, tanδ < 0.05, k_p ~ 0.46, d₃₃ ~ 540 pC/N, P_s ~17 μC/cm²。陶瓷电学性能随温度变化测试结果又表明, BCTZ陶瓷的电学性能具有很强的温度依赖性, 随着温度的升高其电学性能逐渐下降。     

Lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3-Y2O3 ceramics with large piezoelectric coefficient obtained by low-temperature sintering

Lead-free (Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃-xwt.%Y₂O₃ (BCZT-xY) piezoelectric ceramics have been synthesized using solid-state reaction technique and the effects of Y₂O₃ addition on the phase structure and piezoelectric properties of the ceramics have been studied. The results reveal that the addition of Y₂O₃ significantly improves the sinterability of BCZT ceramics, resulting in a reduction of sintering temperature from 1,540 to 1,350 °C, and an increase of the Curie temperature T _C from 85 to 95 °C. X-ray diffraction data shows that Y₂O₃ diffuses into the lattice of BCZT-xY ceramics and a pure perovskite phase forms in the ceramics. Scanning electron microscopy images indicate that a small amount of Y₂O₃ addition affects the microstructure, obviously. Main piezoelectric parameters of these ceramics are optimized around x = 0.06 wt % with a large piezoelectric coefficient (d ₃₃  = 560 pC/N), a high planar electromechanical coefficient (k _p  = 53 %) and a low dissipation factor (tan δ = 0.9 %) at 1 kHz. The results indicate that the BCZT-xY ceramics are promising lead-free materials for practical applications.     

(Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3无铅压电陶瓷的相结构与压电性能

钙锆共掺钛酸钡陶瓷(BCZT)具有优异的介电性能和压电性能, 是一类具有发展潜力的无铅压电陶瓷, 但其压电性能仍无法与铅基陶瓷媲美。为提高压电性能, 本研究对陶瓷材料进行Sn元素掺杂改性((Ba_0.85Ca_0.15)- (Ti_0.9Zr_0.1-xSn_x)O₃, x=0.02~0.07))。晶体结构分析证实所有组分的陶瓷无杂相, 处于正交相与四方相两相共存状态, 并具有较大的c/a; 显微结构分析发现所有陶瓷都很致密, 且平均晶粒尺寸随着Sn含量的增加而增大。当x=0.04时, 陶瓷最致密, 且室温处于准同型相界附近, 因此拥有最佳的电学性能: d₃₃=590 pC•N ^-1, k_p=52.2%, tanδ=0.016, ε ^T₃₃=5372, d ^*₃₃=734 pm•V ^-1, IR=57.8 GΩ•cm。本研究表明: Sn掺杂的BCZT基无铅压电陶瓷具有优异的压电性能, 有望在换能器、机电传感器和驱动器等方面得到应用。     

Orientation-dependent phase transition and dielectric properties of Ba0.85Ca0.15Ti0.9Zr0.1O3 thin films

Polycrystalline Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCZT) thin films with (100) preferential and random orientation are prepared on the LaNiO₃ electrodes coated on Si substrates by chemical solution deposition process. The results show that the two types of films stabilize in the pure perovskite structure. The ferro-paraelectric phase transitions of two types of films occur at the temperature ranges of 280.2–297.8 K and 278.4–287.6 K, respectively. The dielectric constant, relaxation time and tunability of the random orientation film are smaller than those of the (100) preferential film but both almost have the similar leakage current characteristics. The mechanism associated with the change of the electrical properties of the thin films is also discussed.     

Ba(Zr0.15Ti0.85)O3厚膜的介电与铁电性能研究

本研究采用流延法制备Ba(Zr_0.15Ti_0.85)O₃(BZT)厚膜样品。采用扫描电子显微镜分析样品形貌; 采用LCR测试仪和Sawyer-Tower电路法测量样品的介电与铁电性能。结果表明, BZT厚膜具有明显的介电弛豫特征, 击穿电场强度可达60 kV/cm以上, 饱和极化强度可达58.1 μC/ cm², 剩余极化强度(Pr)为20.9 μC/ cm²。     

Effects of cobalt and sintering temperature on electrical properties of Ba0.98Ca0.02Zr0.02Ti0.98O3 lead-free ceramics

Lead-free (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃-xmol% (x = 0–1.6) cobalt ceramics (BCZT-xCo) have been fabricated by the traditional solid-state reaction technique and the effects of Co and sintering temperature on ferroelectric, dielectric and piezoelectric properties of (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃ lead-free ceramics have been studied systematically. The orthorhombic–tetragonal (T _O–T) transition shift towards lower temperature with increasing Co addition, while Curie temperature (T _c) remained at relatively high value of 107 °C. And the Main piezoelectric parameters are optimized at x = 0.8 mol% with a high piezoelectric coefficient (d ₃₃ = 330 pC/N), a planar mode electromechanical coupling factor (k _p = 46.7 %), a high dielectric constant (ε _r = 2,675) and a low dielectric loss (tanδ = 0.90 %) at 1kHZ. Besides these, high remnant polarization (P _r) and low coercive field (E _c) of 11.5 μC/cm², 0.31 kV/cm are also obtained at (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃-0.8 mol%Co lead-free ceramics. Furthermore, greatly enhanced temperature stability of the piezoelectric properties was obtained in the temperature range from 20 to 90 °C. The above results indicate that BCZT-Co ceramics are promising lead-free materials for practical applications.     

Study of structural,impedance spectroscopy and dielectric properties of Li and Al co-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 ceramics

Journal of Materials Science: Materials in Electronics - In this work, we investigate the effect of lithium and aluminium co-doping (0, 0.1, 0.2, and 0.3&nbsp;mol%) on the phase formation,...     

钛锡酸锶钡Ba1-xSrxTi0.90Sn0.10O3陶瓷的结构与介电性能

采用传统陶瓷工艺制备了一系列的钛锡酸锶钡Ba1-xSrxTi0.90Sn0.10O3陶瓷.通过X射线衍射分析了样品的相结构,采用扫描电子显微镜描述了样品的形貌.还研究了介电常数和介电损耗随温度和电场的变化.试验结果表明:用传统的固相反应法制备的钛锡酸锶钡陶瓷的相结构为钙钛矿结构.随着烧结温度的提高,介电常数的峰值呈显著增加,介电损耗在铁电区增加但在顺电区没有明显变化.当Sr的掺入量为14%时得到最大的可调率为82.6%.