Comparative study of the crystal field effects in rare earth oxynitrates

Abstract

The photoluminescence spectra of the lanthanum and gadolinium oxynitrates doped with Eu 3+, REONO 3:Eu 3+ (RE  La and Gd) were measured at 77 and 300 K. The 7 F J ( J0–5) energy level schemes for the 4f 6 electron configuration were simulated by a C 2 ν phenomenological crystal field (CF). The nine non-zero CF parameters for the C 2 ν site symmetry reproduce the experimental energy level schemes with rms deviations of 7 and 5 cm −1 for the LaONO 3 and GdONO 3 hosts, respectively. The CF effect is stronger in the lanthanum host although otherwise the CF parameters for the two oxynitrate hosts differ only slightly. The B 2 k ( k = 2, 4 and 6) values are low indicating only a slight deviation from a higher C 4 ν symmetry. The B 0 2, B 0 4 and B 4 4 parameters assume high values which are similar to those obtained previously for the other RE oxy compounds, i.e. oxyhalides, oxysulfates, oxymolybdates, and oxytungstates. The sixth rank parameters deviate considerably from those obtained for the other RE oxy compounds.