Investigations of Zr–Ni intermetallic compounds by perturbed angular correlations

Abstract The hyperfine interactions experienced by 181 Ta in ZrNi 5 and Zr 2 Ni 7 intermetallic compounds have been investigated by the perturbed angular correlation (PAC) technique. In ZrNi 5 , a strong electric quadrupole interaction (∼40%) with ω Q =72.0(1) Mrad/s, η =0.25(1), δ =0 at room temperature has been found due to the presence of Zr 2 Ni 7 contaminating phase produced during sample preparation in the arc furnace. A weak quadrupole interaction of Zr 2 Ni 7 (∼5%) with ω Q =65(1) Mrad/s, η =0.24(6), δ =0 has also been observed. The cubic component of ZrNi 5 also has been observed (∼40% at room temperature) in this sample along with associated defect (15%). It is found that at 873 K, the cubic fraction increases to ∼54% at the cost of its defect fraction. No magnetic interaction in ZrNi 5 has been observed which supports the earlier PAC results but rules out the result of strong magnetic ordering found from magnetization measurement. In Zr 2 Ni 7 , two regular fractions corresponding to two different crystallographic sites of Zr have been clearly identified with the parameters ω Q (1)=70.9(1) Mrad/s, η (1)=0.28(1), δ =1.3(3)% and ω Q (2)=64(1) Mrad/s, η (2)=0.34(8), δ =0 while contradictory results were reported from previous measurements.