EXAFS方法在金属玻璃结构研究中的误差分析

本文对EXAFS方法在金属玻璃结构研究中所得径向距离的误差进行了分析。所做的模拟计算表明当前流行的关于这个问题的误差理论不能圆满地解释这一现象。本文分析了玻璃态和晶态的相移函数,指出在相似的体系中玻璃态和晶态相移函数与k的关系采用线性函数近似时,其斜率可能是不同的,而且无序度相差越大,两者的偏差可能也越大。在EXAFS数据处理过程中,没有考虑这种偏差的影响是造成EXAFS方法结果中径向距离误差的一个原因。本文还提出了一个修正参考样品(晶态)相移函数斜率偏差的方法,并将它应用于Cu₅₅Zr₄₅金属玻璃的EXAFS数据处理中,所得结果与用X射线异常散射方法测定的结果符合得很好。 关键词：

AN ANALYSIS OF THE ERROR IN EXAFS STUDIES OF METALLIC GLASS

The deviation of radial distance to shorter value in EXAFS studies of metallic glass has been analysed in this paper. Simulation calculations showed that the current error theory can not explain the deviating-to-shorter phenomenon satisfactorily. By comparing the phase-shift function of amorphous state with that of crystalline state, we conclude that in the similar system the slope of amorphous phase-shift function may be different from that of crystalline phase-shift function. Normal EXAFS data processing without evaluating this kind of difference is also a cause of the radial distance deviating-to-shorter error in the EXAFS results. A simple method of correcting the slope of the phase-shift function of the reference sample (crystalline state) has been put forward and applied to the EXAFS data processing of Cu₅₅Zr₄₅ metallic glass. Results are well consistent with the results obtained from X-ray abnormal scattering measurement.