MOSSBAUER AND POSITRON LIFETIME STUDIES OF FETI AND FE46TI50MN4 HYDRIDE SYSTEMS

The intermetallic compounds FeTi and Fe46Ti50Mn4 and their hydrides ar e investigated with Mossbauer spectroscopy. The isomer shift of the in termetallic compound FeTi was found to be negative at room temperature relative to the centre of the a-iron and isomer shift change from neg ative to positive with hydrogen absorption pressure. The quadrupole sp litting is observed at 12 atm hydrogen pressure in FeTi system. The is omer shift was also found to be negative in the Fe46Ti50Mn4 compound r elative to the centre of iron and found to be decreasing in negative v alue with hydrogen absorption pressure towards the centroid. It is sug gested that changes in the isomer shift is due to charge transfer from alloy to hydrogen with pressure because Fe is combined with the less electronegative partner element. According to the concept of electrone gativity the large difference in electronegativity is needed to facili tate the charge transfer to hydrogen. The positron life-time measureme nts were also carried out to confirm the hydrogen interaction process with alloys. The positron life-time increases in hydrides in compariso n to the parent intermetallic alloy because hydrogen takes electron fr om the conduction band of FeTi and Fe46Ti50Mn4 during the absorption p rocess. It was suggested that hydrogen interacts with the FeTi alloy o beying the anionic model. Copyright (C) 1996 Published by Elsevier Sci ence