Evidence for clustering in Mn-doped CeO2

Electron spin resonance spectra of manganese-doped cerium oxide have been studied at room temperature for Ce concentrations between 0.01 and 1.00 mol%. The linewidths and intensities of the lines associated with isolated manganese ions have a maximum between 0.20 and 0.40 mol%. The results suggest that the solid solution of Mn in CeO₂ is not random, but exhibits significant clustering effects.