Crystal-field ground states

Table 17. Crystal field ground state anticipated on the basis of a first-nearest-neighbor point-charge model for the rare-earth dihydrides. Both hydridic and protonic hydrogen are considered, and the known experimental results are shown. (146).

ABa intermetallic compounds (A = Y, La, Ce, Lu B = Ir, Rh) with Gd " and Nd as ESR probes were investigated by Dokter et al. (1977). The measurements were performed on powdered samples in the X-band in the temperature range 1.4<7 <4.1 K. In all compounds investigated, Nd " " has a Fe crystal-field ground state. The hyperfine satellites due to Nd (/ = ) and Nd (/ = ) isotopes with natural abundances are clearly resolved. Taking second-order hyperfine splitting into account the data could well be described and the fitting procedure yielded the Nd hyperfine constant, y4 = 210 10G. 

The case of a one-dimensional distortion (a is non-degenerate) is completely analogous to the magnetic case. Since the latter was discussed in section 5.1.3 we do not discuss it here again. If the distortion is two-dimensional this requires special attention. For example if the crystal-field ground state is Ft, one needs to include anharmonic interaction terms as they may occur for example via in order to avoid that the elastic constants are soft at all temperatures below To (Kanamori, 1960 Pytte, 1971). Furthermore a two-dimensional distortion will lead very often to first order phase transitions as it has been discussed by Kino and Miyahara (1966). 

ErHj Er 2.4 measured Hm and identified crystal field ground state Shenoy et al. (1976)... 

An electron paramagnetic resonance study on Cf(iii) in a Cs2NaLuCl6 host (< 1 % Cf by weight) [154] produced a 10-line spectrum to confirm the nuclear spin to be 9/2. The crystal field ground state was also identified in this work and the nuclear dipole moment of Cf determined to be 0.28... 

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