Effect of Cu ions on the dipole moments and polarization of strontium barium niobate single crystals

The crystal growth, the ferroelectric hysteresis loops, and the infrared reflectivity spectra of copper-modified strontium barium niobate (SBN) single crystals are reported. Compared with the undoped SBN crystals, the copper-modified crystals have stable hysteresis loops, the spontaneous polarization of which is about 0.30 C/m(2), but that of the undoped SBN crystals is only about 0.12 C/m(2). Their coercive field strength is all about 340 V/mm. The experimental results of the infrared spec tra show that the infrared reflectivities vary as the orientations of the dipole moments owing to the copper-doping. The c-axis becomes the most stable orientation of the dipole moments, and the polarization will be locked and won't recede if the copper-modified crystals are polarized into monodomains.