Abstract
The purpose of this work is to get some information on the correlation between the change in crystal structure of atomic long-range order and that in crystal field of short-range order during mechanochemical processes. The x-ray diffraction patterns and the fine structures of fluorescence spectra from doped Sm ions were observed on several TiO2 crystals which were prepared by various procedures. TiO2(Sm) of anatase type changed to that of rutile type by grinding. The fine structure of spectrum changed from anatase to rutile almost in parallel to the corresponding change in x-ray pattern. It shows that no essential difference exists between the long-range reordering and the short-range reordering during the mechanochemical phase change. The broadening of fine structures of spectra, however, was observed in neither well ground TiO2(Sm) nor amorphous TiO2 fired at temperatures lower than the crystallization temperature. Such amorphous phase of TiO2 is considered to have a definite crystal field due to the ionic surrounding having the short-range order. This seems quite different from usual inorganic glasses, which give fluorescence spectra with broad structures from doped Sm ions.
