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Electrical conductivity and conduction mechanisms in (Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> ) <sub/>1?x</sub> (BiScO <sub/>3</sub> ) <sub/>x</sub> (0.00 ≤ <i>x</i> ≤ 0.25) solid solutions
摘要： The electrical properties of (Na0.5Bi0.5TiO3)1-x(BiScO3)x (NBT-BS, 0.00 ≤ x ≤ 0.25) solid solutions are established by ac impedance spectroscopy and electromotive force transport number measurements. The bulk conductivity decreases with increasing BS incorporation but the oxide-ion transport number remains high (≥0.85) over a wide compositional range 0.00 ≤ x ≤ 0.15 and drops to ≈0.7 for x ≥ 0.20. NBT-BS solid solutions can only present either predominant oxide-ion conduction or mixed ionic-electronic conduction behaviour, indicating that oxide-ion conduction cannot be fully eliminated by incorporation of BS. This is in contrast from our previous study where incorporation of ≈7% BiAlO3 (BA) can fully suppress the oxide-ion conduction in NBT. The conductivity–composition relationships of NBT-BS solid solutions are attributed to a competing effect from lattice expansion, which enlarges the channel for oxygen ion migration, with trapping between B-site acceptor ions, Sc'Ti, and oxygen vacancies, V??O, which decreases oxygen ion migration. Comparisons between NBT-BS, NBT-BA and NBT-BiGaO3 (BG) solid solutions suggest that small acceptor ions on the B-site are more effective in trapping oxygen vacancies and consequently more effective to suppress the oxide-ion conduction and thus reduce dielectric loss at elevated temperatures.
关键词： transport number,electrical conductivity,solid solutions,sodium bismuth titanate,oxide-ion conduction,conduction mechanisms,impedance spectroscopy,BiScO3
更新于2025-11-14 17:28:48
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Construction of high <i>T</i> <sub/>c</sub> BiScO <sub/>3</sub> -BiFeO <sub/>3</sub> -PbTiO <sub/>3</sub> and its enhanced piezoelectric properties by sintering in oxygen atmosphere
摘要： The high-temperature piezoelectric ceramics 0.36[(1 ? x)BiScO3-xBiFeO3]-0.64PbTiO3 was constructed by introducing BiFeO3 with a high Curie temperature (Tc ～ 830 °C) in the 0.36BiScO3-0.64PbTiO3 binary system. In terms of microstructure, low-melting BiFeO3 plays a role as a sintering aid, lowering the sintering temperature of the ceramic and signi?cantly increasing the grain size. At the same time, the crystal structure shifts from the initial morphotropic phase boundary to the tetragonal phase side, and the Tc increased gradually with increasing BiFeO3 content. Under the conventional air atmosphere sintering conditions, the Tc of the sample with x = 0.3 can reach ～500 °C, and the piezoelectric constant d33 is 125 pC/N. Compared with that, the d33 of the same composition sample sintered in an oxygen atmosphere is increased to 165 pC/N, which is mainly due to the decrease in the content of oxygen vacancies that helps to increase poling electrical ?eld. Moreover, the oxygen-sintered specimen exhibits an excellent thermal stability in a wide temperature range from room temperature to 450 °C, indicating that it is a promising candidate for ultra-high-temperature piezoelectric devices applications.
关键词： high-temperature piezoelectric ceramics,thermal stability,BiScO3-BiFeO3-PbTiO3,sintering in oxygen atmosphere,piezoelectric properties
更新于2025-09-11 14:15:04