The aragonite-type neodymium borate NdBO3: Energy levels, crystal field, and paramagnetic susceptibility calculations

Optical absorption spectra of NdBO3 single crystals were measured between 3900 and 31,700 cm−1 at liquid helium to room temperature. The derived energy level scheme with 119 levels was simulated according to the crystal field theory including free ion effects yielding a rms deviation of 15 cm−1. The 14 free ion and 14 crystal field parameters allowed by the Cs symmetry of the neodymium site were calculated. The derived wavefunctions were used in calculating the paramagnetic susceptibility and its variation with the temperature between 4.2 and 500 K by the van Vleck formula. Experimental and calculated values are in good agreement.