MATERIAU A CHANGEMENT DE PHASE A DENSITE STABILISEE

A phase change material for use is a heat battery is provided whichincludes a salt of hydrated Group IIA metal nitrate and Group IA metal nitrate and aneffective amount of as aqueous material sufficient to cause the densities of the liquidand solid phases of said phase change materiel to be approximately equal during phasetransformation. A method of malting the phase change material and a heat battery whichcontains the phase change material are also provided.