氯化镧单晶的坩埚下降法生长

Growth of LaCl_3 Single Crystals by Vertical Bridgman Method

报道了LaCl3单晶的非真空密闭条件下的坩埚下降法生长方法。依据差热/热重分析所揭示的LaCl3.7H2O脱水过程,采用干燥氯化氢保护下的焙烧脱水处理制备出无水LaCl3原料。将无水LaCl3密封于铂坩埚中,且添加少量活性碳粉,可避免熔体的氧化与挥发,从而实现在非真空条件下的LaCl3单晶生长。在单晶生长过程中,炉体控制温度为940~970℃,固液界面温度梯度为30~40℃.cm-1,坩埚下降速率控制于0.5~1.0 mm.h-1,在非真空密闭条件下成功生长出直径为25 mm的透明LaCl3单晶。综合运用差热/热重分析、X射线衍射、透射光谱、X射线激发发射光谱对所获单晶样品进行了测试表征,表明非真空密闭坩埚下降法适合于生长均匀透明LaCl3单晶。

The growth of LaCl3 single crystals by the vertical Bridgman process in a non-vacuum atmosphere was reported in this paper. According to the dehydration procedure of LaCl3·7H2O investigated by DTA/ TG, anhydrous LaCl3 was prepared by means of heating LaCl3·7H20 in dried HCl atmosphere. The anhydrous LaCl3 was used as the feed material for LaCl3 crystal growth. By means of sealing the feed material with a small amount of active carbon in a platinum crucible, the crystal could be grown in a non-vacuum atmosphere as the oxidization and volatilization of the melt could be avoided. In the Bridgrnan growth process, the crystal was grown with the optimum conditions such as a growth rate of 0.5 - 1.0 mm·h^ - 1 and a temperature gradient of 30 - 40℃ · cm ^- 1 across solidliquid interface at 940 - 970 ℃. A transparent LaCl3 single crystal with 25 mm in diameter was grown by vertical Bridgman process in a non-vacuum atmosphere successfully. The crystal was characterized by DTA/ TG, XRD, optical transmission and X-ray stimulated luminescence measurement. The Bridgman process in non-vacuum atmosphere was confirmed to be promising for growing transparent LaCl3 crystals with high optical quality.