Identification of phase components in Zr-Ni and Hf-Ni intermetallic compounds; investigations by perturbed angular correlation spectroscopy and first principles calculations

Abstract

Time-differential perturbed angular correlation (TDPAC) measurements have been carried out in stoichiometric ZrNi 3 and HfNi 3 intermetallic compounds using 181 Ta probe in the temperature range 77-1073 K considering the immense technological applications of Zr-Ni and Hf-Ni intermetallic compounds. In ZrNi 3 , four components due to the production of Zr 2 Ni 7 , Zr 8 Ni 21 , Zr 7 Ni 10 and ZrNi 3 have been found at room temperature. The HfNi 3 sample produces five electric quadrupole interaction frequencies at room temperature. The phase HfNi 3 is strongly produced in stoichiometric sample of HfNi 3 where two non-equivalent Hf sites are found to be present. Besides this phase, two other phases due to Hf 2 Ni 7 and Hf 8 Ni 21 have been found but, we do not observe any phase due to Hf 7 Ni 10 . X-ray diffraction, TEM/energy dispersive X-ray spectroscopy (EDX) and TEM-selected area electron diffraction (SAED) measurements were used to further characterize the investigated materials and it was found that these results agree with the TDPAC results. In order to confirm findings from TDPAC measurements, density functional theory (DFT) based calculations of electric field gradients (EFG) and asymmetry parameters at the sites of 181 Ta probe nucleus were performed. Our calculated results are found to be in excellent agreement with the experimental results.

Crystalline phases in Zr9Ni11 and Hf9Ni11 intermetallics; Investigations by perturbed angular correlation spectroscopy and ab initio calculations

“…The results show (a new component (∼17%) with ω Q = 74.2(4) Mrad/s, η = 0 is found. This new component can be attributed to ZrNi 3 by comparing the results reported from our recent PAC investigations in ZrNi 3[33]. It is known that ZrNi 3 was formed by the peritectoid reaction (Zr 2 Ni 7 +Zr 8 Ni 21 →ZrNi 3 ) at 1193 K[20] and at 1261 K[21].The predominant phase due to ZrNi (63%) is found to be produced here which was first observed at 973 K in the sample.…”

“…Due to chemical similarity, the probe 181 Hf occupies the Zr sites of the compound. Different Zr-Ni and Hf-Ni intermetallic compounds viz., (Zr/Hf) 8 Ni 21 [30], (Zr/Hf) 2 Ni 7 [31,32], (Zr/Hf)Ni 3 [33] were studied earlier by PAC technique. However, any report of PAC measurements in the (Zr/Hf) 9…”

Phase components in Zr7Ni10 and Hf7Ni10 binary alloys; investigations by perturbed angular correlation spectroscopy and first principles calculations

“…This component can be assigned to Zr 2 Ni 7 by comparing with the results found in Zr 2 Ni 7 [31]. In the stoichiometric ZrNi 3 [35] and ZrNi 5 [32] alloys also, the phase Zr 2 Ni 7 was produced as a major component.…”