Polarization and dipole moments of Co-doped potassium sodium strontium barium niobate crystals

Abstract

Single crystals of potassium sodium strontium barium niobate (KNSBN) and cobalt-modified KNSBN were prepared using the Czochralski technique. The ferroelectric hysteresis loops and the infrared reflectivity spectra were collected. Compared with the undoped KNSBN crystals, the cobalt-modified crystals have stable hysteresis loops, whose spontaneous polarization is about 0.17 C/m2 and coercive field strength is about 670 V/mm, but those of the undoped KNSBN crystals are about 0.04 C/m2 and 530 V/mm, respectively. The measured infrared reflectivities vary with the orientations of the dipole moments owing to the Co doping. The c axis becomes the most stable orientation of the dipole moments, and the polarization can be locked and does not recede when the cobalt-modified crystals are polarized into a single domain.