Structure analysis and electrical resistivity of the high- And lowerature phases of NaPd₃Ge₂ single crystal

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 higherature phase of NaPd₃Ge₂ crystallizes in an orthorhombic structure of the space group Imma, while the lowerature 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 lowerature structure is more stable.