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 ZrNi3 and HfNi3 intermetallic compounds using Ta-181 probe in the temperature range 77-1073 K considering the immense technological applications of Zr-Ni and Hf-Ni intermetallic compounds. In ZrNi3, four components due to the production of Zr2Ni7, Zr8Ni21, Zr7Ni10 and ZrNi3 have been found at room temperature. The HfNi3 sample produces five electric quadrupole interaction frequencies at room temperature. The phase HfNi3 is strongly produced in stoichiometric sample of HfNi3 where two non-equivalent Hf sites are found to be present. Besides this phase, two other phases due to Hf2Ni7 and Hf8Ni21 have been found but, we do not observe any phase due to Hf7Ni10. 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 Ta-181 probe nucleus were performed. Our calculated results are found to be in excellent agreement with the experimental results. (C) 2017 Elsevier B.V. All rights reserved.