Effect of Cu ions on the polarization and polar lattice vibrations of potassium sodium strontium barium niobate single crystals

Abstract

The preparation procedure, the hysteresis loops, and the polar lattice vibration spectra of copper-modified potassium sodium strontium barium niobate (KNSBN) single crystals are reported. Compared with the plain KNSBN crystals, the copper-modified crystals have stable hysteresis loops, whose spontaneous polarization is about 0.25 C/${\mathrm{m}}^{2}$, but that of the plain KNSBN crystals is only about 0.10 C/${\mathrm{m}}^{2}$. Their coercive field strength is all about 350 V/mm. Their polar lattice vibration spectra are studied by Raman and IR reflectivity spectroscopy. The experimental results show that the IR reflectivities vary as the orientations of the dipole moments owing to the copper doping, i.e., the effect of the external field on the longitudinal and the transverse dipole moments are weakened and intensified owing to the copper doping, respectively. \textcopyright{} 1996 The American Physical Society.