3. Experimental details Sample of (GeS2)0:3(Sb2S3)0:7glass was prepared in a evacuated silica ampoule from pure elements(99.999% purity), by melting and homogenization at 950 ?C for 12 h.Differential scanning calorimetric (DSC) measurements were performed on ?10 mg bulk sample encapsulated in standard aluminum sample pans,in an atmosphere of dry nitrogen. The instrument was calibrated with indium, lead and zinc standards. Experiments were performed under linear heating rate conditions.