Interpretation of the optical absorption spectrum and of the paramagnetic susceptibility of neodymium A-type sesquioxide

Abstract

A-Nd2O3 is a layer structure built on the (NdO)n+n cation. Data for the 4.2 K optical spectrum and the strongly anisotropic parallel and perpendicular paramagnetic susceptibilities between 4 and 1000 K measured on single crystals, are reproduced using a Hamiltonian, that involves 12 free atom parameters (three Racah’s parameters, the spin–orbit coupling constant, Trees’ parameters α and β, and Judd’s six Tk operators) and six C3v crystal field parameters. The Hamiltonian operates on the 364 kets in 4f3, that is including J mixing. 88 Stark levels (from 0 to 34 000 cm−1) were fitted to a mean square deviation of 17 cm−1. The crystal field parameters (Wybourne’s formalism) are B20=−836 cm−1, B40=634 cm−1, B43=−1606 cm−1, B60=752 cm−1, B63=237 cm−1, B66=672 cm−1. The spectrum is strongly displaced to the red with respect to Nd3+ in LaCl3 and this is due to a lowering of Slater’s integrals F2 and F4 by 2% to 3%. The F6 integral is unchanged. The spin–orbit coupling constant is also lowered by 2%. The interaction parameters are slightly affected.

Lanthanide tetrad effect in the Ln3+ ionic radii and refined spin-pairing energy theory

“…These results, obtained by applying the im proved RSPET formulation to U*(LnO1.5, cub) and U*(LnF3, rhm), are consistent with the nephelauxetic series of Ln3+ previously proposed on the basis of the spectroscopic data of elec tronic energy levels of various Ln3" compounds (Jorgensen, 1962(Jorgensen, , 1979Wong et al, 1963;Caro et al, 1981). In particular, Caro et al (1981Caro et al ( , 1979Caro et al ( , 1977 and Antic-Fidancev et al . (1980) reported careful spectroscopic analyses of the electronic energy levels of several Nd31 com pounds including the trifluoride and sesquiox ide.…”

“…The . Correlations between the Racah E' and E 3 parameters and between E' and the spin-orbit coupling con stant ((4f) of various Nd3+ compounds reported by Caro et al (1981Caro et al ( , 1979Caro et al ( , 1977 and Antic-Fidancev et al . (1980).…”

Refinement of the Nd2O3 and Nd2O2S structures at 4 K

“…In Table 3 are reported for both compounds the point-charge distribution (PCEM), the induced-dipoles correction (ID), the total electrostatic parameters corrected for the shielding factor trk and the wave-function expansion, and the experimental c.f.p. as determined by Caro et al (1979) for Nd20 3 and Souillat et aL (1972) for Nd202S. Compared with our earlier work (Faucher et al, 1980), the results of ab initio calculations for Nd20 3 are not much changed since the 4 K structure is not significantly different from the room-temperature structure.…”

“…Experimental values are after Caro et aL (1979) and Souillat et al (1972). Earlier calculations (Faucher et al, 1980) are in parentheses.…”

Crystal-field splittings of gadolinium (4f7) levels in C-type rare earth oxides

“…In this matrix the interelectronic repulsion operator-which acts between states of the same class-will be represented by the appropriate combination of Racah's parameters according to the tables of Nielson and Koster. The spinorbit operator will act between 6p and the other class states, i. e., 8S, 6D, and the two 4D and also between 6F and 6D and ~ (20). The crystal-field operators will connect the states of 6 P and 6 F with those of 6 D. Splittings will be obtained as the result of those multiple offdiagonal interactions.…”