采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Ne...采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Negative Temperature Coefficient)电阻特性,如电阻率(ρ)、热敏常数(B)、线性度和迟滞。实验结果证明:所制备的陶瓷坯体经950℃、1000℃、1050℃和1100℃烧结后可得到纯钙钛矿相的CaCu_(3)Ti_(4)O_(12)陶瓷;同时具有良好的NTC特性,室温电阻率(ρ25)为1.5×107Ω·cm,热敏常数为6223~6874 K;线性度和迟滞分别为1.50%和1.00%。展开更多
通过传统固相法合成了具有超晶格结构的Ba Bi_(8)Ti_(7-x)(Cu_(1/3)Nb_(2/3))_(x)O_(27)(简称:BBT-BIT-x(Cu_(1/3)Nb_(2/3))共生陶瓷。结果表明,BBT-BIT-x(Cu_(1/3)Nb_(2/3))陶瓷的电学性能得到了有效地改善:随着x的增加,介电损耗呈现...通过传统固相法合成了具有超晶格结构的Ba Bi_(8)Ti_(7-x)(Cu_(1/3)Nb_(2/3))_(x)O_(27)(简称:BBT-BIT-x(Cu_(1/3)Nb_(2/3))共生陶瓷。结果表明,BBT-BIT-x(Cu_(1/3)Nb_(2/3))陶瓷的电学性能得到了有效地改善:随着x的增加,介电损耗呈现先减小后增大的趋势,居里温度逐渐增加(Tc:483~494℃);压电常数和剩余极化强度都呈现出先增大后减小的趋势,其中x=0.035时压电常数和剩余极化强度同时达到最高值分别为d_(33)=18 p C/N,2P_(r)=16.5μC/cm^(2)。此外,BBT-BIT-0.035(Cu_(1/3)Nb_(2/3))陶瓷具有良好的热稳定性,在400℃/0.5 h下压电常数仍有14 p C/N,是起始值的82.4%,这有利于在较高温度的环境下工作。展开更多
Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi_4Ti_3O_（12） is a type of ferroelectric ceramics, which is supposed to replace leadcontaining cerami...Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi_4Ti_3O_（12） is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. Ferroelectric ceramics of Bi_4Ti_3O_（12） made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi_4Ti_3O_（12） ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 ℃ or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 ℃, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 ℃, r values peak can reach 205.40 at a frequency of 100 k Hz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of Ea range from 0.52 to 0.68 e V. The dielectric properties of the sample sintered at 1 100 ℃ are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi_4Ti_3O_（12） ceramics are a kind of dielectrics. Thus, Bi_4Ti_3O_（12） can be used in high-temperature capacitors and microwave ceramics.展开更多
文摘采用固相反应法制备了Ca Cu_(3)Ti_(4)O_(12)(CCTO)及Y^(3+)掺杂的Ca_(0.97)Y_(0.03)Cu_(3)Ti_(4)O_(12) (CYCTO)陶瓷,研究了陶瓷烧成过程中采用随炉冷却和在空气中快速冷却的工艺对陶瓷样品物相结构、微观形貌和介电性能的影响。结果表明,当采用随炉冷却工艺时,Y^(3+)掺杂的CYCTO陶瓷的介电常数(ε′)相对于未掺杂的CCTO陶瓷有所提高,同时介电损耗(tanδ)也得到同步降低。而当采用在空气中快速冷却的工艺时,CYCTO陶瓷的ε′和tanδ得到进一步优化。阻抗分析表明,在空气中快速冷却的CYCTO陶瓷的晶粒导电性和晶界的绝缘性得到同步提高,从而增强了CYCTO陶瓷的介电响应而提高了ε′;而晶界绝缘性地提高导致了tanδ的进一步降低。快速冷却的CYCTO陶瓷在1 k Hz时,其ε′高达4.06×10~4,tanδ降低到0.036,其介电性能比随炉冷却的CCTO陶瓷(ε′=1.68×10~4,tanδ=0.16)得到显著提升。
文摘采用溶胶-凝胶法制备了CaCu_(3)Ti_(4)O_(12)粉体,压制成型工艺和传统烧结工艺制备了CaCu_(3)Ti_(4)O_(12)陶瓷样品,研究了CaCu_(3)Ti_(4)O_(12)陶瓷的相结构与烧结工艺的关系,表征并讨论了CaCu_(3)Ti_(4)O_(12)陶瓷的负温度系数(NTC,Negative Temperature Coefficient)电阻特性,如电阻率(ρ)、热敏常数(B)、线性度和迟滞。实验结果证明:所制备的陶瓷坯体经950℃、1000℃、1050℃和1100℃烧结后可得到纯钙钛矿相的CaCu_(3)Ti_(4)O_(12)陶瓷;同时具有良好的NTC特性,室温电阻率(ρ25)为1.5×107Ω·cm,热敏常数为6223~6874 K;线性度和迟滞分别为1.50%和1.00%。
文摘通过传统固相法合成了具有超晶格结构的Ba Bi_(8)Ti_(7-x)(Cu_(1/3)Nb_(2/3))_(x)O_(27)(简称:BBT-BIT-x(Cu_(1/3)Nb_(2/3))共生陶瓷。结果表明,BBT-BIT-x(Cu_(1/3)Nb_(2/3))陶瓷的电学性能得到了有效地改善:随着x的增加,介电损耗呈现先减小后增大的趋势,居里温度逐渐增加(Tc:483~494℃);压电常数和剩余极化强度都呈现出先增大后减小的趋势,其中x=0.035时压电常数和剩余极化强度同时达到最高值分别为d_(33)=18 p C/N,2P_(r)=16.5μC/cm^(2)。此外,BBT-BIT-0.035(Cu_(1/3)Nb_(2/3))陶瓷具有良好的热稳定性,在400℃/0.5 h下压电常数仍有14 p C/N,是起始值的82.4%,这有利于在较高温度的环境下工作。
基金Funded by Hubei Provincial Department of Education(No.D20161006)
文摘Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi_4Ti_3O_（12） is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. Ferroelectric ceramics of Bi_4Ti_3O_（12） made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi_4Ti_3O_（12） ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 ℃ or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 ℃, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 ℃, r values peak can reach 205.40 at a frequency of 100 k Hz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of Ea range from 0.52 to 0.68 e V. The dielectric properties of the sample sintered at 1 100 ℃ are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi_4Ti_3O_（12） ceramics are a kind of dielectrics. Thus, Bi_4Ti_3O_（12） can be used in high-temperature capacitors and microwave ceramics.
