Impurity effects on anatase-rutile transformation.

概要

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Impurity effects on the phase transformation from anatase to rutile were studied under normal atmospheric conditions. The rate equation of this phase transformation is explained by the Avrami model. Impurities of metal oxides having MO6 octahedra in a structural unit plays a very important role on anatase-rutile transformation, and V2O5 reacts as an accelerator, while WO3, Nb2O5, Ta2O5 and Cr2O3 are of inhibitors. The activation energy of this phase transformation was given to be 50 kcal/mol from pure anatase, 35 kcal/mol from antase stabilized by H3PO4, and 125 kcal/mol from anatase added W03 as an impurity. The value of the activation energy from pure antase was about half of the smallest one reported previously. The variation of the activation energy reflects the difference in the inhibiting mechanism of anatase stabilized by H3PO4 or WO3.
日本鉱物科学会の論文