The crystal structure and electronic properties of a new metastable non-stoichiometricBaAl4-type compound crystallized from amorphousLa6Ni34Ge60 alloy

Abstract

A new metastable La–Ge–Ni ternaryBaAl4-type(ThCr2Si2-type) compound, of which the space group isI4/mmm is synthesized. It is obtained by a polymorphic transformation from anLa6Ni34Ge60 amorphous alloy on crystallizing. The formula of the compound is(La0.3Ge0.7)(Ni0.85Ge0.15)2Ge2. This indicates that it is highly non-stoichiometric compared to the stoichiometricLaNi2Ge2. It is foundthat the c-axis lattice parameter of this compound is much longer than that ofLaNi2Ge2. It should be notedthat the longer c-axis unit cell parameter is attributable only to the longer interlayer distance between Ge site andNi site layers. The temperature dependences of electrical resistivity and thermoelectric power of the(La0.3Ge0.7)(Ni0.85Ge0.15)2Ge2 compoundand La6Ni34Ge60 amorphous alloy are also clarified. The comparison of these electronic properties betweenthe two materials indicates that sp-electrons mainly contribute to the density of statesaround the Fermi level of this compound.