Remarkably High-Temperature Stability Of Bi(Fe_(1-X)Al_X)O_3-Batio_3 Solid Solution With Near-Zero Temperature Coefficient Of Piezoelectric Properties

摘要

The 0.72Bi(Fe_(1-x)Al_xO_3-0.28BaTiO_3 (x = 0, 0.01, 0.03, 0.05, and 0.07, abbreviated as Bfax-BT) lead-free high-temperature ceramics were prepared by the conventional ceramic processing. Systematic investigation on the microstructures, crystalline structures, dielectric and piezoelectric properties, and high-temperature stability of piezoelectric properties was carried out. The crystalline structures of Bfax-BT ceramics evolve from rhombohedral structure with x < 0.01 to the coexistence of rhombohedral structure and pseudocubic phases with x ≈ 0.01, finally to pseudocubic phases when x > 0.03. Remarkably high-temperature stability with near-zero temperature coefficient of piezoelectric properties (TCk_p), together with improved piezoelectric properties has been achieved for x = 0.01 Bfax-BT ceramics. The Bfax-BT(x = 0.01) ceramics simultaneously show the excellent piezoelectric properties of d_(33) = 151 pc/N, k_p = 0.31 and super-high-temperature stability of T_d = 420℃, TCk_p = 1 x 10~_(-4). It is considered that the observed strong piezoelectricity and remarkably high-temperature stability should be ascribed to the phase coexistence of rhombohedral and pseudocubic phases. The rhombohedral phases have a positive TCk_p value and the pseudocubic phases possess a negative TCk_p value. Thus, the TCk_p value of Bfax-BT ceramics can be tuned by composition of x.