Crystal structure and electrical properties of Li/Mn co-doped NBT-based Aurivillius-type ceramics

New Aurivillius-type ceramics, (NaBi)(0.5-x)(LiMn)(x)Bi4Ti4O15 (NBTLM-100x), are prepared by using the solid-state reaction process with a lower sintering temperature (T-s) of 960 degrees C, the relationship between structure (grain, phase, domain and crystal structure) and high-temperature properties (piezo-/ferro-electric prop-erties and resistances) of Li/Mn doped NBT-based ceramics are investigated systematically. The results show that, the replacement of Na/Bi with Li/Mn frees up more space for cations at the center of the oxygen octahedrons, which increases the ferroelectric to paraelectric phase transition temperature (T-C), and changes the tilt and rotation of Ti-O octahedrons, leading to an increase in spontaneous polarization (P-s), NBTLM-2 ceramics have the maximum P-s along the a-axis of -43.24 mu C/cm(2). Meanwhile, in the Li/Mn substituted ceramics, the substitution for Bi and the lower T-s suppress the formation of oxygen vacancies, contributing to the domains switching and the promising piezoelectric properties. The high temperature conduction mechanisms of the NBTLM-100x ceramics are also fully explored, the decrease of hole concentration, attributing to the donor dopping and reduced oxygen vacancy concentration, favors the high resistivity. In this work, the NBTLM-2 ceramics obtain the excellent properties of TC = 664 degrees C, d(33) = 33 pC/N and rho(dc) (at 500 degrees C) = 1.55 x 10(7) Omega center dot cm, indicating the enormous potential in the high temperature piezoelectric devises. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that Li/Mn doping increases the ferroelectric/paraelectric phase transition temperature and spontaneous polarization in ceramic structures, while also suppressing the formation of oxygen vacancies and increasing resistance, resulting in excellent high-temperature piezoelectric properties.