Effect of the element ratio in the doping component on the properties of 0.975(0.8Bi_(1/2)Na_(1/2)TiO_3-0.2Bi_(1/2)K_(1/2)TiO_3)-0.025Bi_(x/3)Mg_(y/3)Nb_(z/3)O_3 ceramics

摘要

A new series of ternary perovskite 0.975(0.8Bi_(1/2)Na_(1/2)TiO_3-0.2Bi_(1/2)K_(1/2)TiO_3)-0.025Bi_(x/3)Mg_(y/3)Nb_(z/3)O_3 (BNT-BKT-BMN, BMN-xyz) ceramics were designed and synthesized. The effect of the element ratio in the doping component BMN on the strain, ferroelectric, piezoelectric, and dielectric properties of the BNT-BKT matrix were studied. The BMN-430 composition without Nb element exhibits the typical features of non-ergodic relaxor, which is characterized by a higher piezoelectric coefficient d_(33) and a butterfly-shaped strain curve with negative strain. The introduction of trace Nb can significantly enhance the ergodicity of the system, reflecting in the high positive strain response and strain coefficient (d*_(33) ＞ 750 pm/V) of BMN-321 composition. In contrast, there is no significant difference in the properties between the presence and absence of Mg element. The temperature-dependent electrical behaviors of BMN-xyz ceramics were analyzed based on impedance spectroscopy. This study may be helpful to the design of the chemical modification strategy for the BNT-based relaxor ferroelectrics.