Preparation, characterization. and low-temperature heat capacities of nanocrystalline TiO2 ultrafine powder

Nanocrystalline TiO2 ultrafine powders with different grain sizes have been prepared by the sol-gel method. The grain sizes and the crystalline phases have been determined, Heat capacities in the temperature range of 78-370 K have also been measured, and the polynomial equations expressing the chang e of heat capacity with temperature were fitted. The obtained values of the heat capacity have been compared with those of the bulk crystal from the L iterature, The relations between heat capacity and the grain size of nanocr ystalline TiO2 have been discussed in terms of energy. (C) 2001 Academic Pr ess.