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

Abstract

Crystalline phases formed in stoichiometric Zr 9 Ni 11 and Hf 9 Ni 11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr 9 Ni 11 , the phases Zr 9 Ni 11 (∼89%) and Zr 8 Ni 21 (∼11%) have been found at room temperature from PAC measurements. At 773 K, Zr 9 Ni 11 partially decomposes to Zr 7 Ni 10 and at 973 K, it is completely decomposed to ZrNi and Zr 7 Ni 10 .In Hf 9 Ni 11 , a predominant phase (∼81%) due to HfNi is found at room temperature while the phase Hf 9 Ni 11 is produced as a minor phase (∼19%). No compositional phase change at higher temperature is found in Hf 9 Ni 11 . Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr 9 Ni 11 and Hf 9 Ni 11 have been calculated