Nuclear Magnetic Resonance Study ofAl27in NiAl

The NMR of ${\mathrm{Al}}^{27}$ has been studied in two samples of the bcc ordered alloy NiAl whose atomic compositions were 48% Ni, 52% Al and 50% Ni, 50% Al. The line intensity of the first sample is accounted for by assuming all satellite transitions wiped out by quadrupolar interactions with defects. The width of the observed -½⇄½ transition was 4.5±0.3 Oe, field- and temperature-independent, and can be almost entirely accounted for by ${\mathrm{Al}}^{27}$ dipole-dipole interactions. The second sample had an 11% greater width and 85% greater intensity, indicating contributions from satellite transitions. The Knight shift of both samples was 0.055±0.005%, which is only one-third that of pure aluminum, and was independent of magnetic field and temperature. The specific heat of NiAl was measured from 2.2 to 4.2°K, giving ${\gamma }_{\mathrm{el}}=12.6\mathrm{}\times {10}^3$ ergs ${\mathrm{mole}}^{-1\mathrm{}}$ °${\mathrm{K}}^{-2\mathrm{}}$, which is 87% of the value for pure aluminum. We conclude that the low value of the Knight shift results from a small Fermi-contact interaction at the aluminum sites for electrons at the Fermi surface and is not due to a low density of states.