Direct measurement of surface energy of CeO₂ by differential scanning calorimetry

Surface energy of cerium oxide was measured by differential scanning calorimetry (DSC). Nanocrystalline CeO₂ samples were synthesized by a nonaqueous sol-gel method and their surface and interfacial areas were determined from nitrogen adsorption, X-ray diffraction, and electron microscopy measurements. Three samples were repeatedly heated in a differential scanning calorimeter and the excess enthalpy was obtained from the difference in DSC traces between first heating, during which coarsening occurred, and second heating. Surface enthalpy was calculated from excess enthalpy and from changes in surface and interfacial areas. The measured surface enthalpy for CeO ₂, 1.2 ± 0.2 J/m², is consistent with values from oxide melt solution calorimetry on samples with different surface areas. This is the first successful measurement of surface energy using scanning calorimetry.