Electrical Properties and Tracer Diffusion of Oxygen in Some Bi-based Lead-free Piezoelectric Ceramics

Abstract

The relationship between electrical properties and oxygen tracer diffusion was focused for Bi based piezoelectric ceramics including typical perovskite ferroelectrics, (Bi_1/2Na_1/2)TiO₃ (BNT), and Bi layer-structured ferroelectrics, Bi₄Ti₃O₁₂ (BIT). The oxygen tracer diffusion was investigated by a secondary ion mass spectrometry, SIMS. Volume diffusion coefficients, D_v, of ¹⁸O in Bi excess BNT (BNT+Bi₂O₃ 0.3 wt%, BNT-0.3) and V-substituted BIT (Bi₄Ti_3-xV_xO₁₂, BITV-x, x=0.04) ceramics dramatically decreased as compared with those in non-doped ceramics. These results suggest that the concentration of oxygen vacancies decreased in both systems. On the other hand, electromechanical coupling factor, k₃₃, for BNT-0.3 and BITV-0.02 ceramics are 0.47 and 0.25, respectively, which are the largest in each system.