Piezoelectric (Na_(0.5)K_(0.5))NbO_3-SrTiO_3 Ceramics in the Tetragonal-Orthorhombic Phase Boundary Studied by Raman Spectroscopy

摘要

Raman spectroscopy of lead-free piezoelectric (1-x)(Na_(0.5)K_(0.5))NbO_3-xSrTiO_3 ceramics and (Na_(1-y)K_y)NbO_3 ones sintered by the Spark-Plasma-Sintering method have been performed to investigate the dynamical property in the intermediate phase of x = 0.05. From the comparison of Raman spectra between (1-x)(Na_(0.5)K_(0.5))NbO_3-xSrTiO_3 and (Na_(1-y)K_y)NbO_3 at room temperature, the overdamped mode which became soften was found in the intermediate phase at x = 0.05. Although it is difficult to assign the mode because of using ceramics samples, this result has a possibility that the overdamped mode includes the soft mode observed in the orthorhombic phase.