Modification of hydriding properties of LaCo 5 by partial substitutions (LaCo 5− xMx with M = Al, Ga)

Abstract

By partial substitution of Co in LaCo 5 by nontransition metals such as Al, an increase in H capacity ( z) vis-a-vis LaCo 5 is achieved at pressures on the order of 100 atm at room temperature. Lower equilibrium pressures, P e, have been previously observed when compounds such as PrCo 5 and LaNi 5 were partially substituted on transition metal sites by nontransition metals such as Al, Be. This fact, coupled with the existence of the high-pressure phase LaCo 5H z with z ≅ 9, suggests that the increased z is due to a lowering of P e of the high-pressure phase to more modest conditions in temperature and pressure. The actual P( z) curves are, however, complex and reflect phenomenology often observed with pseudo-binaries.