Comparative NMR study of hybridization effect and structural stability in D 022 -type Nb Al3 and Nb Ga3

With the aim of providing experimental information for the correlation between p-d hybridization and phase stability in the D 022 structure, we performed a comparative investigation on Nb Al3 and Nb Ga3 using Nb93 NMR spectroscopy. The quadrupole splittings, Knight shifts, and spin-lattice relaxation times (T1 's) for each individual compound have been identified. The larger quadrupole interaction and higher anisotropic Knight shift have been observed in Nb Al3, indicative of the stronger hybridization effect for this material, as compared with its isostructural compound Nb Ga3. Results of experimental T1 together with theoretical band structure calculations provide a measure of d -character Fermi-level density of states Nd (EF) and an indication of orbital weights. In addition, we found evidence that Nd (EF) correlates with the structural stability of the studied materials. Our NMR measurements confirm that Nb Al3 is more stable than Nb Ga3 with respect to the D 022 structure, attributed to the stronger p-d hybridization in the former material.