The anomalous crystal field splittings of 2H11-2 Nd 3 , 4f3Report as inadecuate

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Abstract : The experimental splitting of some particular electronic energy levels of trivalent rare earths deviates strongly from predicted values. It happens namely for the 2H11-2 level of Nd3+ at 16 000 cm-1 above the ground state. The disagreement is so systematic and conspicuous whatever the compound that it cannot be assigned to an imperfection of the fitting procedure but rather to a specific failure of crystal field theory. The experimental splitting of the 2H11-2 level can be reproduced by utilizing for this level only, high values of Racah-s parameter E2 or high crystal field parameters B2 0 . But also, it is noteworthy that the magnitude of the discrepancy is strongly related to the behaviour of the level when it is coupled with its « twin », displaying the same S, L, and J values and observed at about 35 000 cm-1. It is proposed that some mechanism uncouples all the twin levels. Refinements of free-ion and crystal field parameters are fulfilled with uncoupled twins for LiYF4 : Nd3+, NdOCl, and Y2O3 : Nd3+ and yield rather satisfactory results.

Keywords : crystal field interactions impurity electron states lithium compounds neodymium neodymium compounds yttrium compounds

Author: M. Faucher D. Garcia P. Caro J. Derouet P. Porcher



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