Improvement in crystalline perfection, piezo-electric property and optical transparency of in-situ poled Fe–LiNbO3 single crystals by post growth annealing and poling

Crystalline perfection, piezoelectric response and optical transparency of in-situ poled Fe–LiNbO3 single crystals was studied. Very low angle grain boundaries and the variations in the piezoelectric charge constant d33 were observed in the as-grown crystals. Grain boundaries were successfully removed at higher annealing temperatures but the d33 value was decreased. Low crystalline perfection and d33 were observed after poling the annealed specimen. These parameters were improved by low temperature annealing followed by very slow cooling. FTIR spectra revealed that OH– and CO32– ionic defects were present in the as-grown crystals. The OH– ion concentration was reduced, CO32– ions were removed and optical quality was improved after annealing at higher temperatures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)