Neodymium crystal fields

A study of the crystal field interaction in NdAlg by heat capacity, susceptibility, and resistivity measurements over the range 4—300K has been reported. Thermal transformations in thiourea compounds of neodymium, samarium, europium, and gadolinium have been shown to take place according to the scheme M(C3H302)3, CS(NH2)2,3H20 M(C3M,02) CSfNH ) NH CNS MO-... 

Figure 12.11 Optical spectra of Cr-doped lanthanum (a) and neodymium (b) orthogallates. Variation of Cr crystal field strength 0Dq) and interelectronic repulsion (Racah B) in the function of Ga-Cr substitution in lanthanum (c) and neodymium (d) orthogallates. 

The mean deviation resulting from experimental/calculated fits is usually satisfactory. The accuracy does not depend only on the number of levels (for instance 91 versus 364 for trivalent praseodymium and neodymium, respectively), but also on the strength of the crystal field. While the deviation is 6cm and 10cm for Pr " and Nd doped in LaCls respectively, it rises up to 31 and 15cm in Y2O3. 

The most glaring discrepancy quoted at the begiiming of this section is the case of the H(2)ii/2 level of triply ionized neodymium. It persisted for a long time in spite of clear experimental evidence (see for instance Caro et al. 1981). Faucher and Garcia (1988) and Faucher et al. (1989a,b) showed that the anomaly touched the rank-four crystal field only they suspected that it concerned twin levels only and proposed an empirical rule to take it into account for any neodymium compound within the classical one-electron cfp fitting. The same type of correction applies to the H(2)n/2 level of trivalent erbium in the complementary 4f configuration (Moune et al. 1991). 

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