Science and Technology on Plasma Dynamics Lab, Air Force Engineering University, Xi'an, 710038, P.R. China.
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P.R. China.
Sci Rep. 2017 Jun 23;7(1):4193. doi: 10.1038/s41598-017-03266-y.
Bismuth titanate BiTiO (BiT), was one of the most promising lead-free high-temperature piezoelectric materials, due to high Curie temperature (675 °C) and large spontaneous polarization (50 µC/cm); however, extensive studies had revealed that high leakage conductivity interferes with the poling process, hindering its practical applications. In this paper, an electrically insulating property was achieved by a low level Nb donor substitution to suppress a high level of holes associated with high oxygen vacancy concentration. BiTiNbO ceramic showed significant enhancements of electrical resistivity by more than three order of magnitude and activity energy with value >1.2 eV, which are significant for piezoelectric applications of BiT-based materials. However, pure and AO-excess (A = Bi, La and Nd; 3 at %) BiT ceramics, were mixed hole and oxygen ion conductors. Schottky barriers were both formed at grain boundary region and the sample-electrode interface, because of the existence of semiconducting bulk. Interestingly, the electron conduction could be suppressed in N, as a consequence, they became oxide ion conductors with conductivity of about 4 × 10 S cm at 600 °C.
钛酸铋（BiTiO，BiT）是最有前途的无铅高温压电材料之一，因为它具有高居里温度（675°C）和大自发极化（50 µC/cm）；然而，广泛的研究表明，高漏电导率会干扰极化过程，阻碍其实际应用。在本文中，通过低浓度的 Nb 施主取代来抑制与高氧空位浓度相关的高浓度空穴，从而获得电绝缘性能。BiTiNbO 陶瓷的电阻率提高了三个数量级以上，激活能超过 1.2eV，这对于基于 BiT 的材料的压电应用非常重要。然而，纯和 AO 过量（A=Bi、La 和 Nd；3at%）BiT 陶瓷是混合空穴和氧离子导体。由于存在半导体体相，肖特基势垒在晶界区域和样品-电极界面都形成了。有趣的是，在 N 中可以抑制电子传导，因此，它们在 600°C 时成为电导率约为 4×10^-4 S/cm 的氧离子导体。
