Hyperfine interactions in Cd-111-doped lutetium sesquioxide

We report here first Perturbed Angular Correlation (PAC) results of the ele ctric field gradient (EFG) characterisation at Cd-111 impurities located at both non-equivalent cation sites of the bixbyite structure of Lutetium ses quioxide, between room temperature (RT) and 1273 K. The comparison with res ults coming from a systematic Cd-111 PAC study in bixbyites and with point- charge model (PCM) predictions shows the presence of a trapped defect at RT in the neighbourhood of the asymmetric cation site, which is completely re moved at T > 623 K. The anomalous EFG temperature dependence in Lu2O3 can b e described in the frame of a "two-state" model with fluctuating interactio ns, which enables the experimental determination of the acceptor energy lev el introduced by the Cd impurity in the band-gap of the semiconductor and t he estimation of the oxygen vacancy density in the sample.