Polarization and Dipole Moments of Manganese-Modified Potassium Sodium Strontium Barium Niobate Crystals

The crystal growth, the ferroelectric hysteresis loops, and the infrared reflectivity spectra of manganese-modified potassium sodium strontium barium niobate (KNSBN) single crystals are reported. Compared with the undoped KNSBN crystals, the manganese-modified crystals have stable hysteresis loops, whose spontaneous polarization is about 0.18 C/m(2) and coercive field strength is about 600 V/mm, but those of the undoped KNSBN crystals are about 0.04 C/m(2) and 530 V/mm, respectivery. The experimental results of the infrared reflectivity spectra show that the infrared reflectivities vary as the orientations of the dipole moments. The c-axis becomes the stablest orientation of the dipole moments owing to the manganese doping, and the polarization will be locked and not recede if the manganese-modified crystals are polarized into mono-domain.