Discussion about procedure for determining parameter α in Modified Williamson-Hall method

Synopsis: In Modified Williamson-Hall / Warren-Averbach (MWH/WA) method, the estimation of parameter α is of vital importance for obtaining other parameters accurately. Almost all researchers use the procedure for determining parameter α proposed by Ungár et al. (route 1), which includes the rough approximation. On the other hand, Takebayashi et al. suggested an improved procedure (route 2) which could give more precise results. By comparing above two routes, it is found that route 1 can result in overestimated (about twice) α values and significantly impacts further analysis in MWH/WA method due to ignored terms. Since the difference of α value affects the crystallite size D and parameter π, the application of route 2 is recommended in MWH/WA method.