The effect of adding a bit of Fe to Ag-Ge-Se system

ARCONDO, B.; MARIA ANDREA UREÑA; ERAZU, M.; ROCCA, J.; FONTANA, M.

Kanpur, India

Conferencia; International Conference on the Applications of the Mössbauer Effect (ICAME 2007); 2007

Ag-Ge-Se system is an easy glass former in a wide composition range not far from the Se corner of the equilibrium phase diagram. Glasses can be obtained either as films or in bulk form. However, the existence of liquid immiscibility gaps causes an impact on the glass morphology where Ag-rich zones alternate with Ag depleted ones which size depends on composition. In order to analyze the short range order, a bit of Fe, with more than 90% 57Fe, was added as a probe in the synthesis stage of these glasses. Due to their low phonon energy, 0.5% Fe is incorporated in these glasses without apparent segregation. As a reference, Fe doped binary and ternary crystalline phases were also synthesized. Mössbauer spectra of these glasses were obtained at room and lower temperatures. Two types of environments were observed, characterized by broad doublets that can be assigned to Fe in non magnetic environments. The corresponding Debye temperatures, which depend on the composition of the glass, were determined. Additionally, magnetization was measured as a function of temperature and applied magnetic field. From M(H) and M(T) curves it is evident that the magnetization of the glasses has two components, i.e., a blocked one even up to room temperature that saturates at low field, and a paramagnetic (or superparamagnetic) one which does not saturate even at the largest applied field.    The Mössbauer spectroscopy results are discussed and correlated to their morphology and to the magnetic behavior of glasses and crystalline phases.