Published online by Cambridge University Press: 25 February 2011
The excess enthalpy and excess heat capacity of nanophase TiO2 prepared by a chemically-derived process and by inert gas condensation have been measured using differential scanning calorimetry. In comparison to the chemically-derived samples, the excess enthalpy of the inert gas condensed samples is significantly larger, perhaps due to the presence of intragranular planar defects that accomm oate oxygen deficiency. Significant extraneous contributions from planar defects, lattice strain, phase transformation, oxidation, or sintering have been ruled out for the chemically-derived samples. A grain boundary enthalpy of 13-1.6 J/m2 in the temperature range 600-1000°C is obtained from scanning measurements. However, the data also indicate a grain size and/or temperature dependence of the grain boundary enthalpy.