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

Valparaiso, Chile

Conferencia; Sólidos 2009; 2009

Universidad tecnica federico santa maria

Agx(GeySe1-y)1-x glasses have caused great impact for at least two decades due to their remarkable transport properties. Glasses with y~0.25at. are semiconductors for x<0.08at. whereas for x≥0.08at. they are fast ionic conductors. This abrupt change of transport regime (seven orders of magnitude for conductivity) takes place in a very narrow composition range and is a consequence of the inhomogeneous morphology of these glasses controlled by a large miscibility gap in the liquid phase of the Se-Ag2Se-GeSe2 system. Spinodal decomposition is observed upon solidification in a narrow composition range (0.08-0.10at.) outflanked by zones that present binodal decompositions.With the aim to correlate conductivity and morphology with structure, amorphous samples of compositions Agx(Ge0.25Se0.75)1-x with 0≤x≤0.25 were analyzed by means of extended X-ray absorption fine structure (EXAFS) and Mössbauer effect (ME) spectroscopies. EXAFS analyses (Ge and Se K-edges) were performed at different temperatures and Mössbauer spectroscopy in transmission geometry with 119mSnO3Ca source was performed at 300 K on 119Sn atoms introduced as substitution impurity for Ge.