Nonmetallic behaviour in half-Heusler phases YPdSb, YPtSb and LuPtSb

We present the results of combined macroscopic [magnetic susceptibility, heat capacity, electrical resistivity] and microscopic [nuclear magnetic resonance (NMR)] studies of half Heusler phases YPdSb, YPtSb and LuPtSb. The bulk results indicated diamagnetic and nonmetallic behaviours. The Solomon quadrupolar echoes revealed for all three materials the presence of some static electric field gradients, and thus some small deviation from the perfect cubic symmetry. The spin-lattice relaxation rates of the 121,123Sb nuclei were shown to be nonmetallic, quadrupolar in nature and due to the dominant two-phonon Raman processes.