Evidence was provided here for an unexpected increase in the paramagnetic centre concentration with increasing GeO2 (5 to 50mol%) content in GeO2–ZrO2 co-precipitates prepared by the NH3-promoted hydrolysis of ZrO(NO3)2 and GeO2 (hex) aqueous solutions followed by drying and gradual calcination in air at 300 to 900C. A possible mechanism for defect formation was proposed. An increase in paramagnetic centre concentration was associated with the peculiarities of the Ge–Zr hydroxide thermal dehydration process and structure-type transition.

Origin of Paramagnetic Centres in GeO2–ZrO2 Prepared by Co-Precipitation in Aqueous Solution. E.V.Frolova, M.I.Ivanovskaya: Solid State Ionics, 2004, 173[1-4], 125-30