Rapid identification of structural phases in combinatorial thin-film libraries using x-ray diffraction and non-negative matrix factorization

In this work we apply a technique called non-negative matrix factorization (NMF) to the problem of analyzing hundreds of x-ray microdiffraction $(μXRD)$ patterns from a combinatorial materials library. An in-house scanning x-ray microdiffractometer is used to obtain $μXRD$ patterns from 273 different compositions on a single composition spread library. NMF is then used to identify the unique $μXRD$ patterns present in the system and quantify the contribution of each of these basis patterns to each experimental diffraction pattern. As a baseline, the results of NMF are compared to the results obtained using principle component analysis. The basis patterns found using NMF are then compared to reference patterns from a database of known structural patterns in order to identify known structures. As an example system, we explore a region of the Fe–Ga–Pd ternary system. The use of NMF in this case reduces the arduous task of analyzing hundreds of $μXRD$ patterns to the much smaller task of identifying only nine $μXRD$ patterns.