Interpretation of the optical absorption spectrum and of the paramagnetic susceptibility of NdAlO3

Abstract

The absorption spectrum of pure rhombohedral NdAlO3 was determined at 4.2 K from 10 000 to 34 000 cm−1. Adding the levels determined for the 4I multiplet by other authors, a total of 117 Stark levels was obtained. They were fitted to a mean square deviation of 13 cm−1 with a Hamiltonian involving 12 free atom parameters and six D3 crystal field parameters applied on the 364 kets basis in the 4f3 configuration. The values are B02=−481 cm−1, B04 =481 cm−1, B34=−390 cm−1, B06=−1700 cm−1, B36=−950 cm−1, B66=−1080 cm−1. Free atom parameters are very close to those of Nd3+ in LaCl3. The powder paramagnetic susceptibility was measured from 4 to 1000 K. The 1/χ versus T curve shows a pronounced curvature, even below 300 K, which is fairly well reproduced by a crystal-field-only calculation involving the complete wave vectors of the 18 lowest Kramers doublets.