Effect of B-site Mn/W Co-doping on Electrical Properties of Bi₄Ti₃O₁₂ Bismuth Layered Piezoelectric Ceramics

Mn/W co-doped Bi₄Ti_3-x(Mn_1/3W_2/3)_xO₁₂ (BITMW-100x, 0.01≤x≤0.07) bismuth layered high temperature piezoelectric ceramics were prepared by using direct reaction sintering method. The effects of Mn/W content on structural and electrical properties of the BITMW-100x ceramics were studied. XRD results indicated that all samples exhibited typical bismuth layered structure. With increasing content of Mn/W, grain size of the ceramic grains increased first and then decreased. Dielectric loss of the Bi₄Ti₃O₁₂ ceramic samples is effectively suppressed after the doping with Mn/W, while the Curie temperature shows a slight reduction. Owing to the decrease in the concentration of oxygen vacancy in the Bi₄Ti₃O₁₂ ceramics after replacing Ti, the pinning effect of oxygen vacancies on electric domains is weakened, so that the piezoelectric coefficient is increased. When the Mn/W doping content is x=0.05, the ceramic samples have the optimal overall performance,with dielectric loss (tanδ) of 0.7%, Curie temperature of 674 ℃ and piezoelectric constant (d₃₃) of 18.1 pC·N^-1. Meanwhile,the piezoelectric constant has promising thermal stability.