Considerations For Batio_3 Ceramics With High Piezoelectric Properties Fabricated By Microwave Sintering Method

摘要

A decrease in the domain size of barium titanate (BaTiO_3) improves the piezoelectric constant (d_(33)). Other considerations suggest the high d_(33) of BaTiO_3 may be caused by the enhanced high dielectric constant (ε_(33)~T/ε_0) at room temperature due to the size effect. However, we have clarified that even a sample with a low (ε_(33)~T/ε_0) shows high d_(33) according to the optimization of microwave sintering conditions. We have verified that the d_(33 of BaTiO_3 ceramics fabricated by microwave sintering is as high as 37pC/N despite the (ε_(33)~T/ε_0) of 2100. Mechanisms affecting d_(33) in microwave sintering and in conventional sintering of BaTiO_3 are thought to be different. The relationship between the grain size, the mechanical quality factor Q_m, and the frequency constant N_p, which was obtained from microwave sintering, has assumed that a decrease in grain size causes a decrease in internal stress. We suggest that a decrease in internal stress induces continuity of strain in a grain boundary, resulting in continuity of domains across a grain boundary.