Mössbauer studies of the alloys Fe3Ga4, (Fe1-xTix)3Ga4 and (Fe1-yCry)3Ga4

Abstract

The crystal structure of the alloy Fe3Ga has four inequivalent crystallographic iron sites. Mössbauer spectra recorded at 4.2 K were able to be fitted with four sextets corresponding to these sites. Measurement of the hyperfine fields Bhf gave values 271 kG, 191 kG, 152 kG and 195 kG respectively. For the series (Fe1-xTix)3Ga4 spectra were recorded at 4.2 and 300 K for x = 0.05, x = 0.10 and x = 0.15. These spectra were fitted to five sextets, each associated with a distinct iron site. The magnetic ordering temperature TC was observed to be essentially unchanged for 0 x0.15. Site preference for Ti atoms was observed for x = 0.10 and x = 0.15 causing a large change in hyperfine field values at a neighbouring site. Similar Mössbauer studies were made on the series (Fe1-yCry)3Ga4 (0 y0.20). Spectra at 4.2 K could be fitted with four sextets but continuous reductions in hyperfine field values and ordering temperature TC were observed with increasing y. The contrast in the magnetic behaviour of the two series is associated with different patterns of substitutional site preference.