The influences of structure and size of titanium dioxide nanoparticles (TiO_2 NPs) on the crystallization and melting properties of deionized water (DW) were studied by differential scanning calorimetry (DSC). The results show that adding TiO_2 NPs leads to an increase in onset crystallization temperature and a decrease in melting time of DW, however, it hasn't influences on crystallization time and onset melting temperature of DW. Latent heats of crystallization and melting of DW can be increased by adding NPs at high cooling rates. Compared with TiO_2-anatase NPs, TiO_2-rutile NPs' influences on phase transition properties of DW are stronger. An increase in size of NPs results in an increase in crystallization temperature but a decrease in melting time and latent heats of DW. Additionally, crystallization kinetics was analyzed by Avrami method. The Avrami exponents of 1.43 ～ 1.73 suggest that ice crystal structure isn't influenced by structure and size of NPs.
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