Structural and Electrical Properties of Mg²⁺-doped BBTI-BIT Ceramics

BaBi₈Ti_7−xMg_xO_27−δ (x=0, 0.2, 0.4, 0.6, 0.8) intergrowth bismuth layered lead-free piezoelectric ceramics were prepared by using the conventional solid-state reaction method. The effect of Mg²⁺ on structure, electrical properties and temperature stability of the ceramics was studied. All the samples have a single phase structure. With increasing content of Mg²⁺, both the dielectric constant and dielectric loss showed a decreasing trend, while the impedance and activation energy increase at high temperatures. In addition, a small quantity of Mg²⁺ resulted in a variation in the microstructure from plate-like grains to particle-like grains, leading to an improvement in piezoelectric properties of the ceramics. The sample with x=0.60 exhibited optimum electrical properties, with Curie temperature of about 480 ℃ and piezoelectric constant (d₃₃) of 18.8 pC·N⁻¹, which is higher than that of the undoped sample by about 250%.