Dispersions of Metastable High Temperature Cubie Silver Iodide

Abstract

The crystalline forms of silver iodide are reviewed. By means of double-jet precipitation using gelatin, at 70 °C with a carefully controlled excess of potassium iodide (pl=2-2.5) or silver nitrate (pAg 2-4), bright yellow dispersions are obtained which change to ordinary cream coloured silver iodide slowly upon keeping or instantly upon cooling to 27°C. By means of quantitative measurements of the blue shift of the reflection spectrum, of the volume change on transition, and of X-ray diffraction powder patterns, the presence of the high temperature (> 146°C) form of silver iodide in these dispersions is established.