On the study of zinc doping in congruent LiTaO3 crystals

Zn-doped congruent LiTaO3 single crystals have been grown by the Czochralski technique for various doping concentrations. The as-grown crystals were transparent and void-free. The crystals were characterized by the measurements of composition (by inductively coupled plasma atomic emission spectroscopy (ICP-AES)), UV absorption edge, Curie temperature, refractive index, and Fourier transform infrared spectroscopy (FTIR). During the growth we observed that after a certain amount, it was difficult to add more Zn into the grown crystal due to its high volatility and low segregation coefficient. From the ICP-AES study, we also found that the Li/Ta ratio was decreased with the increasing Zn/Ta ratio. The blue shift in absorption edge was observed in Zn doped crystals as compared with the undoped ones. The Curie temperature increased with the increasing Zn concentration and the position of OH− ions was studied by FTIR as well.