X-ray diffraction on – and – composites

We have identified the crystallographic phases of the melt-quenched superionic composites ( AgI ) 0.7 – ( NaPO 3 ) 0.3 and ( AgI ) 0.8 – ( NaPO 3 ) 0.2 by X-ray diffraction. Measurements were made in a temperature range from 300 to 630 K. The materials have a glass phase and one or more crystalline phases. At 300 K and at 350 K, the crystalline phase contains a 30:70 mixture of \beta AgI and \gamma AgI. Above 350 K, the fraction of \beta AgI increases and at 403 K it is the dominant phase with a \beta – \gamma ratio of about 70:30 (slightly less in ( AgI ) 0.8 – ( NaPO 3 ) 0.2 ). At 453, 523 and 623 K the crystalline material is mainly \alpha AgI. Crystalline 16-silver dodecaiodide diphosphate ( Ag 16 I 12 P 2 O 7 ) is also present between 373 and 523 K at a 5–10% level. It disappears at 623 K because the crystal melts.