Hyperfine Interaction Study of Te Doped FexSb1-x Alloy

Hyperfine Interaction technique like Mossbauer spectroscopy is a very sensitive tool to study the local probe interactions in Iron rich alloys. We report here the Mossbauer study of the effect of Fe concentration variations in Te doped Fe_xSb_1-x for x = 0.05, 0.10, 0.20 and 0.50 alloys. Also for a very dilute Fe concentration (0.008), Te concentration is varied from 0.01 to 0.03. From the Mossbauer spectroscopy for x=0.008 to 0.10 keeping Te concentration y= 0.01 only a doublet (site A) is observed. But as the concentration of Fe is increased to x= 0.20 two quadrupole sites (A and B) are observed. The quadrupole splitting for site A is˜ 1.28±0.02 mm/sec and site B is˜ 0.30±0.02 mm/sec respectively. The observed value of quadrupole splitting for site A is constant with the increase in Iron concentration from x = 0.05 to 0.20. The value of isomer shifts for site A is found to be 0.46±0.02 mm/sec for x = 0.05-0.20 whereas, site B is 0.40±0.02 mm/sec for x = 0.20 and 0.50. At highest concentration of Iron (x =0.50) site A disappears. This two quadrupole sites A and B are assigned to the formation of FeSb₂ and FeTe compound phase respectively. For very low concentration of Fe (0.008) on varying the Te concentration contrary to our expectation, no magnetic interaction is observed.