Structure analysis and electrical resistivity of the high- and low-temperature phases of NaPd3Ge2 single crystal

Abstract

Rod-shaped single crystals of NaPd3Ge2 with a length of ∼1 mm were grown using the self-flux method. The electrical resistivity exhibits a metal-like temperature dependence with a kink at 115 K, which is due to a structural phase transition not observed in the previous study using polycrystalline samples. The high-temperature phase of NaPd3Ge2 crystallizes in an orthorhombic structure of the space group Imma, while the low-temperature phase is isostructural to NaPd3Si2 (space group: Imm2) as determined by the single-crystal X-ray diffraction analyses at 90 K. The density of states and total energies obtained by the density functional theory calculations reveal that both phases are metallic, and the low-temperature structure is more stable.