Magnetic susceptibility and ordering of Yb and Er in phosphors Yb,Er:Lu2O3

Mixed sesquioxides (Lu0.9Er0.1)2O3 and (Lu0.9Yb0.1)2O3 were prepared and analyzed by the XRD and magnetic susceptibility measurements. The samples crystallize in the space group Ia3¯ with a byxbyite structure type. The structure refinement have shown that Er3+ exclusively occupy C2 sites in (Lu0.9Er0.1)2O3, while Yb3+ are preferentially distributed in C3i sites in (Lu0.9Yb0.1)2O3. Magnetic susceptibility data in the whole 2-300 K temperature region was analyzed by the model based on perturbation theory. The mean energy gap between ground and some of the excited crystal field levels (Ei), and their effective magnetic numbers Mieff were determined. The obtained energy levels are compared with theoretical values, and discussed in relation to the cation distribution. An analysis of paramagnetic temperature has shown absence of magnetic ion clustering.