Sn(Ⅳ)-Sb(Ⅲ)-NH_3-NH_4Cl-H_2O体系热力学分析及其应用

Thermodynamic analysis of Sn(Ⅳ)-Sb(Ⅲ)-NH_3-NH_4Cl-H_2O system and its application

应用同时平衡原理和电中性原理对Sn(Ⅳ)-Sb(Ⅲ)-NH3-NH4Cl-H2O体系进行热力学分析,得到标准状态下该体系的[Sn4+]T和[Sb3+]T与pH值之间的关系曲线,以此为基础对该体系的沉淀机理进行研究。研究结果表明:体系pH值决定沉淀反应的可行性和反应进行的方向;采用常规共沉淀方法制得的锑掺杂二氧化锡前驱体为Sn(OH)4和Sb4O5Cl22种沉淀的不均匀混合物;添加缓释剂进行均相沉淀、采用并流沉淀或在沉淀反应前使用适当的配位剂可获得锑掺杂均匀的二氧化锡。

According to the principles of simultaneous equilibrium and electronic charge neutrulity,the thermodynamics analysis of Sn（Ⅳ）-Sb（Ⅲ）-NH3-NH4Cl-H2O system in normal condition was carried out. The relation between the total concentrations of Sn^4＋ and Sb^3＋ and pH value was obtained. Based on the thermodynamics analysis results, the precipitation mechanism was also analyzed. The results show that pH value is a very important factor which determines the co-precipitation reaction direction and feasibility in this system. Antimony doped tin oxide powder prepared by routine way is actually the asymmetric compound of Sn（OH）4 and Sb4O5Cl2. By adopting such methods as even phase precipitation, equal-flow precipitation, and proper complex compound,the homogeneous antimony doped tin oxide powder can be prepared.