杂质离子在Sr(NO_3)_2晶体中分凝行为的研究

STUDY ON THE DISTRIBUTION OF IMPURITIES IN Sr(NO_3)_2 CRYSTALS

本工作研究了Ba2 + ,Pb2 + ,Ca2 + 等 9种金属离子在Sr(NO3) 2 晶体生长过程中的分凝行为 .采用蒸发溶剂方法生长晶体 .蒸发溶剂的温度固定在 45℃ .掺杂离子在初始溶液中的浓度的摩尔分数为 0 .2 %～ 0 .0 2 % .使用等离子发射光谱和电子探针测定了杂质离子在溶液和晶体中的分布 .研究发现 :主体相Sr(NO3) 2 和杂质硝酸盐结构的类同性 ,是杂质离子易于进入晶格的关键因素 ;杂质硝酸盐的溶解度越小 ,杂质越容易进入晶体 ;在同一晶体中Ba2 + 离子在 (10 0 )扇形富集 ,它与晶体在不同结晶方向的表面结构有关 .

The distribution behavior of nine kinds of metal ions such as Ba2+ etc was studied. The crystal was grown by the solvent evaporation method with constant temperature of 45°C. The concentrations of the impurities in the initial solutions are 0.02-0.2 in molar fractions. The composition of the impurities in the solutions and crystals is measured by the inductively coupled plasma- atomic emission spectrometry (ICP-AES) and electron probe microanalysis (EPMA). It is found that the structure of the nitrate is one of the most important factors to influence the distribution of the impurities between the solid and solution and the solubility of the nitrate is another important one. Due to the isomorphous structure and the less solubility, Ba2+ and Pb2+ were preferably partitioned towards the solid phase. Ba2+ is enriched in (100) sector because the surface structure of (100) and (111) sectors in the Sr(NO3)2 crystal is different.