CaPt4P6, first calcium-containing representative of the ternary pyrite-derived pnictides of the BaPt4As6 type: Synthesis, crystal, and electronic structureстатья
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Аннотация:Mixed calcium-platinum phosphide CaPt4P6 was synthesized using flux-assisted high-temperature ampoule technique. According to single-crystal XRD data it crystallizes in the monoclinic space group C2/c with Z = 4 (a = 8.1361(3) Å, b = 7.9489(3) Å, c = 11.3803(5) Å, β = 90.860(2)o, R1 = 0.0240, wRR2 = 0.0618) and belongs to the BaPt4As6 structure type, the structure of which is derived from pyrite structure where one atom of alkaline earth metal per formula unit occupies P2-unit position. DFT calculations predict all known representatives of the BaPt4As6 structure type to be narrow-gap semiconductors (calculated bandgap values are: 0.43 eV (CaPt4P6), 0.57 eV (SrPt4P6), 0.27 eV (SrPt4As6) and 0.40 eV (BaPt4As6)). Bonding analysis establishes that all these compounds are based on the 3D framework of the Pt-Pn and Pn-Pn interactions, with AE cations occupying the voids with varying degree of the distortion of the AE coordination.