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Free keywords:
titanates; nanotubes; ball milling; structural phase transitions
Catalysts in HRTEM
Abstract:
Structural stability of nanostructured titanates was investigated for further processing and possible applications. With the aim to investigate their mechanochemical stability we applied highenergy ball milling and studied induced phase transitions. Hydrogen titanates having two different morfologies, microcrystals and nanotubes, were taken into consideration. During mechanochemical treatment of both morphologies, we observed the phase transition from hydrogen titanate to TiO2 anatase and then to TiO2 rutile. Anatase to rutile phase transition occurred without appearance of intermediate high pressure TiO2 II typically observed in the case of mechanochemical treatment of TiO2. In the case of microcrystals, phase transition from hydrogen titanate to anatase starts after longer milling time than in the case of nanotubes, which is explained by larger particles sizes of crystalline powder. On the contrary, further phase transition from anatase to rutile was occurred faster in crystalline powder than in the case of nanotubes. The sequence of phase transitions was studied by Raman spectroscopy and X-ray powder diffraction, while morphology and crystal structure at nanoscale were analyzed by high resolution electron microscopy.
