Crystal-field analysis of Ho3+ ions in HoCl3·6H2O

Crystal-field splittings of Ho3+ ions in HoCl3·6H2O are re-analyzed in order to obtain a consistent and standardized crystal-field parameter (CFP) set. Experimental energy levels were fitted to Hamiltonian parameters representing the combined free-ion and crystal-field interactions for a 4f10 ion in the actual C2 symmetry site. A relatively low r.m.s. deviation of 8.8 cm−1 is achieved. The reliable starting values of the CFPs were obtained from superposition model analysis. The crystal-field strength, S, is significantly larger for HoCl3·6H2O (S = 262 cm−1) than for Ho3+:LaCl3 (S = 133 cm−1) or Ho(C2H5SO4)3·9H2O (S = 183 cm−1), in which Ho3+ ion is coordinated by nine chlorine atoms or nine oxygen atoms from water molecules, respectively.