[20a-W833-1~9] 9.1 Dielectrics, ferroelectrics

[20a-W833-9] Evaluation of Ferroelectric Domain and Grain Boundaries by Elastic Constants in Piezoelectric Materials

〇Toshio Ogawa¹, Taiki Ikegaya¹ (1.Shizuoka Inst. Sci. & Tech.)

Keywords:relaxor piezoelectric single crystals,domain boundary,grain boundary

Sound velocities were measured in piezoelectric ceramic disks composed of PZT, lead titanate and lead-free, and relaxor single-crystal plates of (100) 0.70Pb(Mg_1/3Nb_2/3)TiO₃-0.30PbTiO₃ using an ultrasonic precision thickness gauge with high-frequency pulse generation. It was possible to evaluate effects of domain and grain boundaries on elastic constants. The existence of domain boundaries in single-crystal plates caused increasing Young’s modulus (Y), rigidity (G) and decreasing Poisson’s ratio (σ) and bulk modulus (K). The existence of grain boundaries in ceramics caused decreasing transvers wave velocity, as the result, Y and G become smaller, and furthermore, σ and K become larger in comparison with the ones in single-crystal plates.