he spectroscopic properties of the Pr3+ ion in NaGdSb 2O7 are discussed in this paper. The host crystallizes in the orthorhombic weberite crystal structure with the general formula, A 2B2O7. The Pr3+ luminescence is dominated by emission transitions emanating from the 1D2 state. Transient fluorescent decay of the Pr3+ luminescence is indicative of random distribution of Na+ and Gd3+ ions in NaGdSb2O7. The remarkable feature in the spectroscopic properties of the Pr3+ ion is the very low energy of the interconfiguration Pr3+ 4f2→4f15d 1 excitation transition (3.63 eV; 342 nm). The large red shift of the Pr3+ 4f15d1 configuration is connected with significant covalent contribution to the crystal field and the high covalence of the Pr3+O2- bonding is tentatively assigned to chemical covalent bonding within the A3B tetrahedral moieties which surround the O8h2- anion in the weberite structure. A comparative study of the optical properties of Pr3+ in NaGdSb2O7 and La 2Hf2O7, which crystallizes with the pyrochlore structure, is also presented
Optical spectroscopy of Pr3+ in the weberite, NaGdSb2O7: High covalence of Pr3+O2- bonding
BETTINELLI, Marco Giovanni
2014-01-01
Abstract
he spectroscopic properties of the Pr3+ ion in NaGdSb 2O7 are discussed in this paper. The host crystallizes in the orthorhombic weberite crystal structure with the general formula, A 2B2O7. The Pr3+ luminescence is dominated by emission transitions emanating from the 1D2 state. Transient fluorescent decay of the Pr3+ luminescence is indicative of random distribution of Na+ and Gd3+ ions in NaGdSb2O7. The remarkable feature in the spectroscopic properties of the Pr3+ ion is the very low energy of the interconfiguration Pr3+ 4f2→4f15d 1 excitation transition (3.63 eV; 342 nm). The large red shift of the Pr3+ 4f15d1 configuration is connected with significant covalent contribution to the crystal field and the high covalence of the Pr3+O2- bonding is tentatively assigned to chemical covalent bonding within the A3B tetrahedral moieties which surround the O8h2- anion in the weberite structure. A comparative study of the optical properties of Pr3+ in NaGdSb2O7 and La 2Hf2O7, which crystallizes with the pyrochlore structure, is also presentedI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.