Energy levels of Pr3+ in CsPrP4O12 and RbPrP4O12 cyclotetraphosphates

Abstract Single crystals of CsPrP 4 O 12 and RbPrP 4 O 12 cyclotetraphosphates were grown using the flux method. CsPrP 4 O 12 crystallizes in the cubic I-43d space group whereas RbPrP 4 O 12 crystallizes either in the cubic I-43d or monoclinic C2/c space group. The Pr 3+ ions occupy sites of S 4 and C 2 symmetries in the cubic and monoclinic phases, respectively, with an eightfold coordination in both phases. The present work reports on an analysis of the Pr 3+ 4f 2 energy level diagram based on the low temperature fluorescence spectra under laser selective excitation in the 3 P 2 states of the cubic CsPrP 4 O 12 and monoclinic RbPrP 4 O 12 compounds. The experimental energy levels are fitted using the SPECTRA program available on the Argonne National Laboratory website. The best fits lead to standard deviations in the order of 28 and 21 cm −1 for the CsPrP 4 O 12 and RbPrP 4 O 12 materials, respectively.