X線粉末回折データより格子定数及び空間群を求めるプログラム : およその格子定数が分かっている場合

概要

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A computer program is presented for finding the unit-cell constants for a crystal phase from X-ray powder data containing multi-phase diffraction lines. Input data are observed diffraction angles, 2θ_<obs> (orld-values) , allowable errors in diffraction angles, Δ2 θ, approximate unit-cell constants and space group (or lattice type) . The procedure of the program is as follows : (1) Five consecutive low-angle lines are selected by using the input cell constants and the space group (or lattice type) (2) Trial unit-cell constants are obtained from the first 35 lines by using the algorithms given by Takaki et al. [Yogyo-Kyokai-Shi, 95, 610 (1987) , Seramikkusu Ronbunshi, 96, 13 (1988)] . (3) For each of the trial cell constants, diffraction angles are calculated and compared with observed ones. Then number of indexed lines N and the reliability index R for the trial unit cell are calculated. (4) After the calculation, the 10 sets of the unit-cell constants having largest values of N X R are selected. The user can obtain the most suitable unit-cell constants comparing the values of N , R, and N X R. The reliability index R is given by R = 100 X (Number of observed reflections) / (Number of all calculated reflections) , where the observed reflections are those belonging to the observed lines within window widths, ±Δ2θ. The program is written in N_<88>-BASIC.
社団法人日本セラミックス協会の論文
1989-07-01