Rietveld方法中高角数据截断对结果的影响

Rietveld方法是研究晶体结构和微结构的有效方法,但不同的数据处理将直接影响Riotveld方法所给出的结果.该文研究了数据处理中高角数据截取对Rietveld方法结果的影响不同的结构参数对高角数据截取有不同的灵敏度,一般的结构参数在常规衍射角范围就能取得较好的结果,但对轻原子体系和晶胞参数的准确确定,需要在计算中引入一定的高角衍射数据.在参数修正时,可信度因子的值随高角数据的增多而缓慢变化,且对背景参数的改变较为敏感。以至其值的大小不能准确反映晶体结构和微结构模型的有效性.

EFFECTS OF DIFFRACTION ANGLE TRUNCATION ON THE RESULTS OF RIETVELD ANALYSIS

Rietveld method is an efficient way to find out the crystal structure and micro-structure of solids. Data treatment strategy has great effect on the its results. In this paper, the effects of truncating angle on its results were sindied systematically. It was found that the site coordination of heavy atoms can be obtained at medium diffraction angle while it needs more high angle data in order to determine the cell parameters and site coordination of light atoms. With the increase of data at high diffraction angular range, the profile parameters almost keep constants; the changes of numerical criteria of fit(including D-wd) are etermined by background parameters.