Mossbauer studies of the alloys Fe3Ga4, (Fe1-xTix)(3)Ga-4 and (Fe1-yCry)(3)Ga-4

The crystal structure of the alloy Fe3Ga has four inequivalent crystallogra phic iron sites. Mossbauer spectra recorded at 4.2 K were able to be fined with four sextets corresponding to these sites. Measurement of the hyperfin e fields B-hf gave values 271 kG, 191 kG, 152 kG and 195 kG respectively Fo r the series (Fe1-xTix)(3)Ga-4 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 temperatur e Te was observed to be essentially unchanged for 0 less than or equal to x less than or equal to 0.15. Site preference for Ti atoms was observed for x = 0.10 and x = 0.15 causing a large change in hyperfine held values at a neighbouring site. Similar Mossbauer studies were made on the series (Fe1-yCry)(3)Ga-4(0 less than or equal to y less than or equal to 0.20). Spectra at 4.2 K could be f itted with four sextets but continuous reductions in hyperfine field values and ordering temperature T-C were observed with increasing y. The contrast in the magnetic behaviour of the two series is associated with different p atterns of substitutional site preference.