Introduction
The local structure of materials is closely related to their functional properties, a subject that has been extensively studied for cathode materials, solid electrolytes and anode materials for Li-ion batteries, ferroelectric materials (BaTiO₃) and so forth. Pair distribution function (PDF) analysis is widely used to evaluate local structure in materials. The PDF G(r) is directly obtained from the Fourier transform of the structure factor S(Q), which is calculated from an experimental total scattering pattern. Many PDF analysis results focus on whether or not the calculated value Gcalc(r) reproduces the observed value Gobs(r) using the unit-cell of crystalline structures and many other parameters (e.g., broadening factor, damping factor, etc.). PDF is a one-dimensional function depending only on distance r, and it enables the evaluation of interatomic distances and coordination numbers. However, it is difficult to perform precise analysis of local atomic arrangements (e.g., the displacement histogram of each element, the angular histogram and etc.). Total scattering analysis is often used not only for G(r) but also for S(Q) to analyze such three-dimensional local structure.
Recently, there has been an increasing demand to perform local structural analysis using a laboratory instrument that can measure the total scattering profile to a wide Q range. We have already reported that SmartLab equipped with an Ag rotating anode tube and a Si pixel detector for high-energy X-rays can perform the total scattering measurement with extremely low background. The S(Q) for SiO₂ glass measured by SmartLab has the same quality as that obtained from a synchrotron facility. Furthermore, we have released the RMC option, an improved RMC method originally proposed by R. L. Mcgreevy and L. Puzai, in the total scattering analysis plugin of SmartLab Studio II (SLSII). The RMC option can easily evaluate the local structure in a crystalline material. Moreover, we changed the plugin name from “PDF plugin” to “Total X-ray Scattering (TXS) analysis plugin” based on the concept that PDF analysis is a part of total scattering analysis.
In this paper, we introduce the basic functions and features of the TXS analysis plugin using actual analysis data.