27Al NMR study in ZrNiAl

We have studied the microscopic properties of the hexagonal ZrNiAl, a model compound for a wide Family of intermetallic compounds crystallizing in this type of structure, by using Al-27 NMR spectroscopy. We have investigated the lineshape of static and MAS NMR spectra as a function of magnetic field strength (4.7-9.4 T) and temperature (5-300 K). Our data indicate that the Al-27 NMR spectra result from a combined effect of quadrupole and anisotropic shift interactions. The Al-27 nuclei are in an environment characterized by the quadrupole: coupling constant e(2)qQ/h of 3.3 MHz, asymmetry parameter eta (Q) of 0.42, isotropic shift delta (iso) of 393 ppm, shift anisotropy delta (anis) = delta (zz) - (delta (xx) + delta (yy))/2 of 150 ppm, and asymmetry factor eta (s) of 0.5. They are found to be temperature independent. The spin-lattice relaxation rate measured at 7.05 T is proportional to the temperature with T1T = 135 s K. The mechanisms responsible for observed values of delta (iso),delta (anis). T1T, and the enhanced Korringa constant are discussed. (C) 2000 Academic Press.