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Changes in the global bulk and local structures, of three different barium compounds (BaZrO3, BaF2, and BaFCl),were induced by mechanical milling and followed using X-ray powder diffraction (PXRD), subsequent microstructure analysis, and 137Ba solid state NMR spectroscopy. Harder materials like BaZrO3 experience significantly higher structural changes upon milling than softer materials like BaF2. Moreover, soft materials with layered structures, like BaFCl, show a pronounced structural change during the milling process. By combining PXRD and solid state NMR, detailed information on the changes to the global and local structures were obtained, which are of interest for mechanochemical synthesis, mechanically treated catalysts or ionic conductors.
A comprehensive spectroscopic characterization of all known crystalline AlF3 phases (α-, β-, η-, κ-, θ-AlF3) is presented for the first time in this study. Beside their X-ray diffraction powder patterns, which were already published in the literature, 27Al and 19F MAS NMR, FT IR and XPS spectroscopic techniques were applied for all phases in a consistent manner. For all phases prepared the utilization of 27Al satellite transition (SATRAS) NMR allowed to determine the quadrupolar parameters of the aluminium sites including their distributions.
In addition, η-AlF3 was isolated with high phase purity and characterized following a new preparation path different from those known so far in the literature.