The enthalpy of formation of cubic ceria–zirconia solid solutions (c-Ce(1−x)ZrxO2, 0.05 ⩽ x ⩽ 0.75) at 25 °C with respect to monoclinic zirconia (m-ZrO2) and cubic ceria (c-CeO2) has been measured by high-temperature oxide melt solution calorimetry. In contrast to fluorite solid solutions containing trivalent oxides (e.g., yttria–zirconia), mixing in c-Ce1−xZrxO2 shows moderate positive deviation from ideality. Evaluating the data within the framework of a regular solution model, the interaction parameter, Ω, is +51.0 ± 8.0 kJ/mol. The introduction of undersized Zr into CeO2 severely distorts and destabilizes the oxygen sublattice. Destabilization of c-Ce1−xZrxO2 may be relieved by reduction or clustering. A stable ordered compound in the CeO2–ZrO2 system is thermodynamically unlikely.

Oriented single crystals of synthetic alpha-alumina (α-Α12O3), geikielite (MgTiO3), and natural ilmenite (FeTiO3) were irradiated with 200 keV argon ions under cryogenic conditions (100 K) to assess their damage response. Using Rutherford backscattering spectrometry combined with ion channeling techniques, it was found that ilmenite amorphized readily at doses below 5×1014, alumina amorphized at a dose of 1-2x1015, and geikielite was amorphized at -2x1015 Ar cm-2 . The radiation damage response of the ilmenite crystal may be complicated by the presence of hematite exsolution lamellae and the experimentally induced oxidation of iron. The relative radiation-resistance of geikielite holds promise for similar behavior in other Mg-Ti oxides.