助熔剂坩埚下降法生长近化学计量比Co:LiNbO_3晶体

Growth of Near-stoichiometric Co: LiNbO_3 Single Crystals by Flux Bridgman Method

以K2O为助熔剂，在较大的温度梯度（90～100℃／cm）条件下进行引种和晶体生长，应用坩埚下降法成功地生长出了初始Co^2＋掺杂浓度为0．5mol％的近化学计量比的铌酸锂晶体。测定了该晶体的红外光谱与吸收光谱，与同成份的LiNbO，晶体相比，其紫外吸收边向短波方向移动，OH^-红外吸收峰的位置发生变化。观测到520，549，612nm三个分裂的尖吸收峰以及1400nm左右为发光中心的吸收带。从吸收特性可以判断，Co离子在铌酸锂晶体中呈现＋2价。比较上部与下部晶体的吸收强度，可以推测出沿着晶体生长方向Co^2＋离子浓度逐渐降低，Co^2＋离子在晶体中有效的分凝系数大于1。

The near-stoichiometric Co-doped LiNbO3 （Co：SLN）single crystals were grown with the Co^2＋ concentration of 0.5mo1% raw material by the flux Bridgman method. K20 was taken as flux , and a high interface temperature gradient of 90-100℃/cm was taken for the crystal seeding and growing. The UV-IR absorption spectra of Co：SLN crystal were measured. In comparison with congruent LiNbO3 crystal, the absorption edge of Co： SLN crystal was shifted to ultraviolet, and the infrared absorption band of the OH - also changed obviously. Comparing with congruent LiNbO3 crystal, a similar absorption behavior was Observed. There were three absorption peaks at 520, 549, 612nm, and a wide band centered at about 1400nm. It could be deduced from the absorption spectra that the Co ion in Co：SLN crystal existed in ＋ 2 state. By comparing the absorption intensity between the upper and lower parts of Co：SLN crystal, it could be also deduced that Co^2＋ concentration in crystal was reduced along the growing direction, and the effective segregation coefficient was more than 1.