Structure, Electrical Properties, and Thermal Stability of the Mn/Nb Co-Doped Aurivillius-Type Na0.5Bi4.5Ti4O15 High Temperature Piezoelectric Ceramics

Abstract

In order to meet the urgent need for high temperature piezoelectric materials with a Curie temperature over 400 °C, the Mn/Nb co-doped strategy has been proposed to improve the weak piezoelectric performance of the Aurivillius-type Na0.5Bi4.5Ti4O15 (NBT) high temperature piezoelectric ceramics. In this paper, the crystal structure, electrical properties, and thermal stability of the B-site Mn/Nb co-doped Na0.5Bi4.5Ti4-x(Mn1/3Nb2/3)xO15 (NBT-100x) ceramics were systematically investigated by the conventional solid-state reaction method. The crystal structural analysis results indicate that the NBT-100x ceramics have typical bismuth oxide layer type phase structure and high anisotropic plate-like morphology. The lattice parameters and the grain sizes increase with the B-site Mn/Nb co-doped content. The electrical properties were significantly improved by Mn/Nb co-doped modifications. The maximum of the piezoelectric coefficient d33 was found to be 29 pC/N for the NBT-2 ceramics, nearly twice that of the unmodified NBT ceramics. The highest values of the planar electromechanical coupling factor kp and thickness electromechanical coupling factor kt were also obtained for the NBT-2 ceramics, at 5.4% and 31.2%, respectively. The dielectric spectroscopy showed that the Curie temperature Tc of the Mn/Nb co-doped NBT-100x ceramics is slightly higher than that of unmodified NBT ceramics (646 °C). The DC resistivity of the NBT-2 ceramics is higher than 106 Ω∙cm at 500 °C. All the results together with the good thermal stability demonstrated the Mn/Nb co-doped ceramics as an effective method to improve the NBT based piezoelectric ceramics and the potential candidates of the Mn/Nb co-doped NBT-100x ceramics for high temperature piezoelectric applications.

Piezoelectric Properties and Thermal Stability of Pb(Yb1/2Nb1/2)O3-BiScO3-PbTiO3 Ternary Ceramics

“…For commercial lead zirconate-titanate(Pb(Zr,Ti)O 3 , PZT) piezoceramics, which are widely applied, the Curie temperature is usually lower that 300 • C [4]. In recent years, with the rapid development of energy exploration, vehicle manufacturing, the aerospace industry and other fields, piezoelectric materials have increasingly been required to maintain a stable working state in many harsh environments [5]. For example, the electric injection device of an automobile's internal combustion engine requires piezoelectric materials to work stably in a high-temperature environment above 200 • C or even 300 • C. In the process of petroleum prospecting, piezoelectric sensors for detecting oil pressure and other parameters in deep wells also pose new challenges for the use of piezoelectric materials.…”