XPS study of lutetium oxide samples with different hydration/carbonation degrees as a function of the preparation method

Two different air-aged lutetium oxide samples, ex-hydroxide and ex-oxalate, have been characterized by XPS. In the original samples there is an extensive contamination by CO2-3OH- species (O(1s) and C(1s) at 531.6 and 289.4 eV respectively, while the O(1s) peak of O2- ions of the lattice had a BE of 529.3 eV), which has been confirmed by comparison with the spectra of three different lutetium hydroxide/carbonate salts. Fitting of the Lu(4f) level with two doublets differing in energy by 1.2 eV (Lu(4f72) BEs at 7.2 and 8.4 eV) has shown two types of lutetium ions coordinated, one by O2- ions of the oxide framework and the other by CO2-3OH- groups of the contaminating phase. "In situ" outgassing of samples at high temperatures (298