Background

Since 1968 when Reilly and Wiswall [1] discovered the reversible hydro the alloy Mg2Ni to form the ternary hydride Mg2NiH4, its hydriding-dehydr thermal and kinetic properties have been investigated by many resea years, Mg2NiH4 has continued to surprise the researchers by exhibiting s [2] and resistivity anomalies [3], seemingly unpredictably dependent on sample history. Mg2NiH4 has been regarded as a promising metal hydride for hyd increasing the negative electrode capacity in nickel metal hydride (NiM under normal conditions Mg2NiH4 is too stable, i.e. at room temperature is so low that Mg2NiH4 practically does not desorb hydrogen. Therefor stability of Mg2NiH4 be decreased to produce a suitable material for practi Results and discussion On heating and cooling, Mg2NiH4 exhibits a reversible phase transfo accompanied by a distinct colour change from orange grey-black ( Mg2NiH4 exhibits a monoclinic distorted low-temperature (LT) modifi temperature (HT) phase, where magnesium ions form a cube around ze in an antifluorite arrangement. In the HT phase the hydrogen a reorientational motion around the central nickel atom [4]. In the LT phas and an ordered arrangement of slightly distorted tetrahedral NiH4-com neutron diffraction [5]. In addition to this, a frequently occurring stacking unit cell level is introduced into the lattice [5, 6]. If the microtwinning is s the hydride is decreased, making it more practical for hydrogen storage [7 Figure 1- Color changes associated with heatin