Flux Crystal Growth of the Ternary Polygermanide LaPtGe2, a p-Type Metal.

Large plate crystals of LaPtGe₂ have been grown by using an inert indium metal flux. This compound crystallizes in the CeNiSi₂-type structure (orthorhombic space group Cmcm) with lattice parameters a = 4.3770(9) Å, b = 17.186(3) Å, and c = 4.3942(9) Å. The structure of LaPtGe₂ is a three-dimensional framework with alternating PbO-type layers of PtGe and infinite Ge chains, separated by La atoms. Electrical resistivity and Hall effect measurements characterize LaPtGe₂ as a metal with holes that act as the charge carriers. Strong temperature dependence of the Hall coefficient and a violation of Kohler's rule (from magnetoresistance data) both indicate possible multiband effects. The electronic structure calculations suggest the metallic nature of LaPtGe₂ and show that the strongest bonding exists between Pt and Ge within the PbO-type layers. [ABSTRACT FROM AUTHOR]