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We report on the successful synthesis of two new ternary metal-rich phosphides Mo3Ge2P and W3Ge2P, and on their structural, electrical, magnetic, thermal and electronic properties. Mo3Ge2P is thermally stable below 1500 °C, while W3Ge2P decomposes initially at 1110 °C and finally evolves into W, Ge, and P above 1360 °C. They adopt a non-centrosymmetric orthorhombic structure with space group C 2 v 16 — Ama 2 (No. 40). In the unit cell with content Z = 4, Mo (W) atoms are located at two inequivalent sites, respectively 4 b (Mo1/W1) and 8 c (Mo2/W2) Wyckoff positions, Ge and P atoms occupy 8 c and 4 b positions, respectively. The structure is made up of networks organized by edge-shared (Mo1/W1)3P3 planar six-membered rings and edge-shared (Mo2/W2)3Ge3 chair-form six-membered rings. Both compounds exhibit weak magnetism and metallic conduction with electron-dominant charge carriers at high temperatures, as revealed by magnetic susceptibility, electrical resistivity and Seebeck effect. Sommerfeld coefficient γ and Sommerfeld-Wilson ratio R w were derived as 8.87 mJ mol−1 K−2, 1.69 for Mo3Ge2P and 9.85 mJ mol−1 K−2, 1.78 for W3Ge2P, indicating weak electron-electron correlation in the system. Analyses on thermal conductivity ( κ ) suggest a considerable phonon contribution κ L to the total one in these metallic materials. First-principles calculations demonstrate that the Mo-4 d (W-5 d ) orbital electrons dominate the band structures and density of states near the Fermi level.
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