Pressure-Composition Isotherm Model and Its Application to Designing Hydrogen Absorbing Alloys

Since invention of LaNi sub 5 in late 1960s by Phillips Corporation, numerous batteries, and other applications have been made of the material, and at present time LaNi sub 5 batteries have reached at same market level as that of nickel cadmium batteries. In this report, alloy design potentials like 2-element LaNi sub 5 , and TiMn sub 2 type of alloys which has the pressure composition isotherm (PCT) properties are discussed. PCT required by many application systems and devices. Authors discuss design requirements such as need to consider crystal and alloy structure to satisfy required functions of end device or system, and processes that materialize such functionality. In PCT model diagram, the equation for equilibrium hydrogen pressure (P) and hydrogen absorbing quantity (X) indicate separate regions of: primary solid solution of ( alpha phase region), and secondary ( alpha phase region) hydride region. Based on the described model most hydrogen storage alloys shall possess properties of: asymmetry PCT diagram, Plato region gradient, among others as described. Author proceeds win introducing recently developed LaNi sub 15-x-y Mn sub x alloy for heat driven cooling/heating system which is a form of heat pump.