Thermomechanical study of the high temperature phase transition in KH2PO4

The method of thermomechanical analysis (TMA) has been employed to examine the high temperature polymorphic transition in potassium dihydrogen phosphate (KH2PO4). Both loose powder and pressed pellet samples show an anomalous expansion in the temperature region 200–220°C. The anomaly is explained by the occurrence of a sluggish polymorphic transition. The transition has been found to be reversible.