Uranium chalcogenides—III: Heat capacities and thermodynamic properties of US 1·9 and USe 2 from 5 to 350°K

Abstract

Heat capacities have been measured and derived thermodynamic properties calculated for the structurally related US 1·9 and USe 2 phases from 5 to 350°K. Values of the heat capacity ( C p ), entropy ( S° − S° 0) and Gibbs energy function [−( G° − H° 0/ T] at 298·15°K in cal mol −1 °K −1 are 17·68, 25·91 and 13·82 for US 1·9 and 18·92, 31·98 and 17·86 for USe 2, respectively. Schottky-type anomalies are present in US 1·9; a λ-type thermal anomaly with ΔSt = 0·19 cal mole −1 °K −1 occurs at 13·1 °K in USe 2.