A crystallographic study of the acetates of potassium, rubidium and caesium

In the course of a study of the thermal behaviour of the acetates of potassium, rubidium and caesium by crystallographic and physical methods, the lattice parameters and space groups of these compounds have been obtained. A study of the thermal expansion of potassium acetate using a dilatometric method (Hazlewood, Rhodes & Ubbelohde, 1966) has established at least three solid state phase transitions. The present study has been undertaken to establish the structural basis of the transitions. The acetates of rubidium and caesium have been studied for comparison. Room-temperature data were recorded on Weissenberg photographs; at higher temperatures, oscillation photographs recorded on a hemi-cylindrical film holder of 5.75 cm radius have been used. The thcrmostat was similar to that of Parry, Schuyff & Ubbelohde (1965). An electronic controller maintained the temperature within +0.1 °C.