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Theoretical prediction, synthesis, and crystal structure determination of new MAX phase compound V2SnC

Qiang XüKey Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, ChinaYanchun ZhouScience and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology, Beijing, 100076, ChinaHaiming ZhangSchool of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing, 100044, ChinaAnna JiangKey Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, ChinaQuanzheng TaoThin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping, SE-581 83, SwedenJun LuThin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping, SE-581 83, SwedenJohanna RosénThin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping, SE-581 83, SwedenYunhui NiuState Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, ChinaSalvatore GrassoKey Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, ChinaChunfeng HuKey Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China

2020en

ABI

Annotatsiya

Abstract Guided by the theoretical prediction, a new MAX phase V 2 SnC was synthesized experimentally for the first time by reaction of V, Sn, and C mixtures at 1000 °C. The chemical composition and crystal structure of this new compound were identified by the cross-check combination of first-principles calculations, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and high resolution scanning transmission electron microscopy (HR-STEM). The stacking sequence of V 2 C and Sn layers results in a crystal structure of space group P6 3 /mmc. The a - and c -lattice parameters, which were determined by the Rietveld analysis of powder XRD pattern, are 0.2981(0) nm and 1.3470(6) nm, respectively. The atomic positions are V at 4f (1/3, 2/3, 0.0776(5)), Sn at 2d (2/3, 1/3, 1/4), and C at 2a (0, 0, 0). A new set of XRD data of V 2 SnC was also obtained. Theoretical calculations suggest that this new compound is stable with negative formation energy and formation enthalpy, satisfied Born-Huang criteria of mechanical stability, and positive phonon branches over the Brillouin zone. It also has low shear deformation resistance c 44 (second-order elastic constant, c ij ) and shear modulus ( G ), positive Cauchy pressure, and low Pugh’s ratio ( G/B = 0.500 < 0.571), which is regarded as a quasi-ductile MAX phase. The mechanism underpinning the quasi-ductility is associated with the presence of a metallic bond.

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DOI: 10.1007/s40145-020-0391-8

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