Thermal expansion of potassium iodide

Abstract

The thermal expansion of two different specimens of potassium iodide was measured from liquid-air temperatures to 150°C. One specimen was melt grown in our laboratory and other was supplied by Harshaw Chemical Co. The expansion coefficient for the two specimens above room temperature are identical with one another. The high temperature expansion was not influenced by heat, or cold treatment of the specimens. Below 0°C. the thermal expansion of potassium iodide exhibits an anomalous behaviour. Two maxima at -95° and -40°C. and two minima at -60° and -25°C. have been observed. As the length of the specimen varies continuously with the temperature, the transition in this crystal appears to be homomorpous.