Devitrification and Metastability: Revisiting the Phase Diagram of the System AgI:Ag2MoO4

✍ Scribed by Corrado Tomasi; Piercarlo Mustarelli; Aldo Magistris

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 262 KB
• Volume: 140
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.7867

✦ Synopsis

The phase diagram of the AgI (1؊x) (Ag 2 MoO 4 ) x system has been investigated by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). Besides an incongruent 1 : 1 compound that was previously reported by our group, a metastable 2 : 1 crystalline phase is formed at &110°C over the whole composition range. The stability of this phase is strongly temperature-controlled: at &180°C the crystal decomposes in the time scale of a DSC experiment. For x < 0.5 it gives -AgI and the 1 : 1 compound, whereas for x > 0.5 the 1 : 1 and Ag 2 MoO 4 are formed. The glass-forming region spans over the range 0.20 < x < 0.40. Annealing the samples with 04x < 0.33 near 70°C causes all AgI in excess with respect to the 2 : 1 compound to crystallize as phase.