浓度及冷冻鄄解冻处理对CuCl2水溶液中Cu2+区域结构的影响

应用扩展X射线吸收精细结构(EXAFS)光谱研究了CuCl2水溶液中Cu2+的区域环境结构, 通过测定CuCl2水溶液在不同浓度条件下及冷冻-解冻(FT)处理前后Cu K边EXAFS 吸收谱, 研究了浓度及冷冻-解冻处理对Cu2+第一配位层结构的影响. EXAFS实验结果表明, CuCl2水溶液中Cu2+第一配位层距离中心原子Cu最近邻原子为O原子, 配位数介于3.0-4.3之间, Cu—O键长在0.192-0.198 nm 之间, 这种结构与Cu2+的Jahn-Teller效应有关. 不同浓度的CuCl2水溶液中Cu2+的区域环境结构有很大不同, 随着CuCl2水溶液浓度的升高, Cu2+第一配位层配位数减小, Cu—O键伸长. 结构参数拟合结果证实冷冻-解冻处理对Cu2+的区域环境结构有影响, CuCl2溶液经冷冻-解冻处理后, Cu2+第一配位层配位数变大, 热无序度增加.

Effects of Concentration and Freeze-Thaw Treatment on the Local Structure of Cu2+ in CuCl2 Aqueous Solutions

The microscopic local environmental structure of Cu2+ ions in copper chloride solutions was investigated by X-ray absorption fine structure (EXAFS) spectroscopy. The effects of salt concentration and freeze-thaw (FT) treatment on the first coordination shell of Cu2+ were analyzed by examining the Cu K edge EXAFS spectra of CuCl2 aqueous solutions before and after FT treatment at various concentrations. The EXAFS results show that Cu2+ has 3.0-4.3 oxygen nearest neighbors with Cu—O bond length of 0.192 -0.198 nm in the first coordination shell. These structural properties can be ascribed to the Jahn-Teller effect. We found differences in the microscopic local structure of Cu2+ for various concentrations in CuCl2 aqueous solutions.With an increase in the salt concentration, the coordination number of Cu2+ decreases and the Cu—O bond length increases in the first coordination shell. The influence of FT treatment on the microscopic local environmental structure of Cu2+ was determined fromthe fitting results of the structural parameters. The coordination number of Cu2+ in its first coordination shell and the degree of thermal disorder increase when the FT treatment is operated in CuCl2 aqueous solutions.