ELECTRIC-FIELD GRADIENT AND ITS TEMPERATURE-VARIATION AT A TA-181 PROBE IN ZR2FE AND ZR2CO INTERMETALLIC COMPOUNDS

In this paper we report a time differential perturbed angular correlat ion study of electric field gradients and their temperature variation in Zr2T (T=Fe,Co) intermetallic compounds (C16 crystallographic struct ure). Measurements were performed at a Ta-181 radioactive probe in the temperature range 20 K-1173 K. In both samples only one strong asymme tric quadrupole interaction was observed, consistently with one possib le crystallographic position of the probe atom in the studied structur e. The quadrupole coupling constant is equal to 1039(8) MHz with asymm etry parameter eta=0.82 and 889(7) MHz with eta=1 at room temperature for Zr2Fe and Zr2Co respectively. In the investigated temperature rang e a linear dependence of electric field gradient was observed in contr ast to the T-3/2 dependence found in most intermetallic compounds and non-cubic metals.