Method for Studying the Temperature Dynamics of Crystal Structures

Resumo

A new approach to the structural analysis of crystals based on diffraction data obtained in a series of experiments performed at different temperatures (i.e., to the multitemperature structural characterization) is proposed and implemented. Calculations are performed using symmetry-averaged diffraction data. The full-matrix least-squares method is applied to calculate simultaneously the composite structural model from several datasets. The main purpose of the proposed algorithm is to determine which of the refined parameters are general (temperature-stable) and which reflect the dataset individuality (i.e., change with temperature). The method is applied to determine the occupancies of mixed atomic sites in rubidium titanyl phosphate doped with zirconium, to search for the mobile atoms responsible for the ion transport in this crystal, and to study the structural evolution of the boron framework in crystals of rare-earth element dodecaborides (RB₁₂) of several compositions.