Relaxation effects in Fe doped Ag-Ge-Se glasses

CONDE GARRIDO, J. M.; MARIA ANDREA UREÑA; FONTANA, M.; ARCONDO, B.

Lima

Conferencia; XII Latin American Conference on the Applications of the Mössbauer Effect 2010 (LACAME 2010); 2010

In this work glasses of composition Agx(Ge0.25Se0.75)1-x with x ≤ 0.25, doped with 0.5 at.% 57Fe were synthesized by the melt quenching technique and characterized employing X-ray diffractometry and scanning electron microscopy. For 0.05 < x ≤ 0.25 glasses presented a decomposition in two amorphous phases (one of them with a high Ag concentration whereas the other is Ag poor) but no evidence was obtained of iron segregation. These samples were also analyzed by means of Mössbauer effect spectroscopy and the contribution of both phases was identified: high spin Fe2+ in the Ag rich phase and low spin Fe2+ in the Ag poor phase. As quenched as well as aged samples were analyzed and a strong long term relaxation was observed. The contribution of the Ag rich amorphous phase, corresponding to high spin Fe2+ in distorted octahedral environments recedes to the growth of the other amorphous phase. This effect is discussed and related to the glass structure and stability.