Electric-field gradients at the Zr sites in Zr₃Fe: Measured using perturbed-angular-correlation spectroscopy and calculated using band theory

We have measured the electric-field-gradient (EFG) parameters V_ZZ and η and their temperature dependences at the two Zr sites in the intermetallic compound Zr₃Fe using perturbed-angular-correlation spectroscopy and the probe ¹⁸¹Hf→¹⁸¹Ta. At temperatures below the peritectic transformation at ≈ 1158 K, at each Zr site, we observed well-defined EFG's, characterized by sharp spectral lines. A high-frequency, very asymmetric nuclear electric-quadrupole interaction characterizes the first Zr site, which represents approximately one-third of the probes. A low-frequency, nearly axially symmetric nuclear electric-quadrupole interaction characterizes the second Zr site, which represents approximately two-thirds of the probes. Near and above the peritectic transformation, the results show the effects of the decomposition of Zr₃Fe into Zr and Zr₂Fe and subsequent melting. We have compared the values of V_ZZ and η measured at laboratory temperature to those calculated using the first-principles, self-consistent real-space linear muffin-tin atomic sphere approximation (RS-LMTO-ASA) band-theory method. Overall the magnitudes of V_ZZ and η calculated using the RS-LMTO-ASA method agree reasonably well with the experimental values.