Utilizing titanyl sulfate as a TiO2 source, via a novel synthesis method - the detonation method - nanosized TiO2( n-TiO2) powders were prepared. The results showed that the as- prepared n-TiO2 powders did not have enough time to grow into large and fine crystallites, and that the characteristics of high temperature, high pressure and high cooling were helpful in the synthesis of nanosized materials. The anatase phase appeared to be the stable form of nanocrystalline TiO2 at small crystallite sizes to some extent and part of the rutile phase could transform to the anatase phase when the detonation products were oxidized to eliminate the impurities via the combined action of chromic anhydride ( CrO3) and concentrated nitric acid. The main reason resulting in the reversal of stability of anatase and rutile could be the differences in the surface energy of anatase and rutile at small crystallite sizes.
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