Magnetic dipole and electric quadrupole interactions of 181Ta probe in Ni-Hf alloy

The hyperfine interactions of 181Ta probe in the nickel-2 at.% hafnium alloy have been studied by the perturbed angular correlation method in the temperature range 78-1131 K. The magnitude of the magnetic dipole interaction of 181Hf/181Ta substituting in ferromagnetic Ni(Hf) solid solution decreases with increasing temperature. As a result of the restricted solid solubility of Hf in Ni, a second phase (HfNi5) in the Ni-Hf sample was detected. 181Hf/181Ta which resides in HfNi5 senses weak electric quadrupole interaction. The observed anomalous temperature behavior was ascribed to distortions in the HfNi5 cubic phase. The third measured hyperfine interaction corresponds to the quadrupole interaction of 181Hf/181Ta positioned in HfO2 contamination originating from an annealing procedure above 900 K.