Europium in the ultraphosphate lattice: Polarized spectra and structure of EuP5O14

Abstract

The polarized emission and absorption spectra of single crystals of europium ultra(penta)phosphate, EuP5O14, were measured and interpreted. Most of the observed transitions were identified and the energy level structure of the 7F multiplet defined. The over-all site symmetry is found to be extremely low (C1), but in the immediate vicinity of the Eu3+ ion the local symmetry appears to deviate little from C2v. Crystal field calculations were performed for such symmetry and gave a respectable fit to the observed Stark splittings of the 7F multiplet. A simple structural model for the first coordination shell of the Eu3+ ion is proposed, consistent with the spectroscopic behavior and with the signs and relative magnitudes of the calculated crystal field parameters. Finally, the decay times of the 5D0 and 5D1 emitting states of the ion were calculated and found to be consistent with measurement.