Functional materials studies by Mössbauer spectroscopy

Abstract: Mössbauer spectroscopy has been used as a powerful tool to investigate the local properties of some materials suitable as active ingredients in technological applications. The magnetic properties of some magnetic multilayers were investigated using conversion electron Mössbauer spectroscopy. The interface quality of Fe/V(001) multilayers was determined by measuring the hyperfine magnetic field distributions. The wide distributions found were a sign of interface roughness of the order of at least 2 monolayers. Influence of the interlayer exchange coupling was also apparent. In Fe/Co(001) multilayers three different hyperfine field components belonging to interface, interface near and bulk layers could be resolved. The easy axis of magnetisation could also be deduced to be [110].In a study of a Fe/ZnSe heterostructure, no interface diffusion could be seen for the Fe/ZnSe(001) interface. Thus enabling a high interface polarisation, which is necessary for spin polarised tunnelling. Furthermore a complicated magnetic anisotropy situation was found where the iron layers closest to the interface had magnetic moments pointing along [110] while the rest of the iron moments were aligned along [100].Lithium ion cells with η '-Cu6Sn5 and SnB2O4-glass as anodes were investigated using 119Sn Mössbauer spectroscopy in situ during charge and discharge. The compounds formed after lithium-intercalation could thereby be established. In both cells the lithiation resulted in lithium alloying with tin to a maximum composition of Li4.4Sn. It had, however, different implications for the capacity of the cells.Finally, electrochromic SnO films were investigated using 119Sn Mössbauer spectroscopy. The electrochromism could be ascribed to the valence-state change from Sn(IV) to Sn(II) inside the films.