柴式法摻釹鉭酸鋰單晶生長之研究

Abstract

Congruent 0.2 and 0.5 mol% Nd-doped LiTaO3 single crystals were grown by the conventional Czochralski technique. Near-stoichiometric lithium tantalate wafers were also produced from these crystals by the vapor-transport equilibration (VTE) process. The crystals were characterized by the measurements of composition (by inductively coupled plasma atomic emission spectroscopy (ICP-AES), UV absorption edge, Curie temperature and thermal diffusivity. From the ICP-AES study, we found that Li/Ta ratio was increased by the VTE treatment, while Nd/Ta ratio was found to decrease with the crystal length. The blue shift in absorption edge was observed in the VTE treated crystals as compared with the congruent ones. The Curie temperature decreased with the increasing Nd concentration, while thermal conductivity was found to increase after the VTE treatment. FTIR was also conducted to investigate how impurity and Li/Ta affect the OH- vibration mode. And there are two blue shift absorption bands in 0.5mol%Nd:SLT in which we use a Ta vancancy model to explain the phenomenon.