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采用基于密度泛函理论的第一性原理法对Co-Sc体系中Co Sc、Co2Sc和Co Sc2化合物的热力学参数、电子结构和弹性性质进行计算,分析了3种化合物结构的稳定性和力学性能。结果表明:3种化合物Co Sc、Co2Sc和Co Sc2形成能分别是-0.54、-0.51和-0.36 e V,结合能分别为-6.08、-6.07和-5.56 e V。热力学能均是负值,3种化合物能稳定存在。Co Sc、Co2Sc和Co Sc2费米能级分别为0.6、7.8和8.1 e V,Co Sc在费米能级处的电子能量最小稳定性最好。态密度图分析3种化合物都是金属间化合物。Co Sc的Co(p)、(d)轨道和Sc(p)、(d)轨道电子明显重叠,发生了强烈的杂化作用。Co Sc、Co2Sc和Co Sc2体积模量分别为2.7、172.1和59.3 GPa,Co2Sc有最强的抵抗体积变化特性。Co Sc、Co2Sc和Co Sc2剪切模量分别为72.7、70.1和20.9GPa,Co Sc的刚度相对较强。Co Sc的B/G<1.75为脆性材料,而Co2Sc、Co Sc2的B/G分别为2.46、2.84为塑性材料。
The thermodynamic parameters, electronic structure and elastic properties of Co Sc, Co2Sc and Co Sc2 compounds in Co-Sc system were calculated by the first principle method based on density functional theory. The stability and mechanical properties of the three compounds were analyzed . The results show that the formation energies of Co Sc, Co2Sc and Co Sc2 of the three compounds are -0.54, -0.51 and -0.36 eV respectively, and the binding energies are -6.08, -6.07 and -5.56 eV, respectively. Thermodynamics can all be negative, three kinds of compounds can exist stably. The Co Fermi levels of Co Sc, Co2Sc and Co Sc2 are 0.6, 7.8 and 8.1 eV, respectively. The minimum energy stability of Co Sc at the Fermi level is the best. State density map analysis of the three compounds are intermetallic compounds. The Co (p), (d) orbital and Sc (p), (d) orbital electrons of Co Sc obviously overlapped and strong hybridization occurred. Co Sc, Co2Sc and Co Sc2 bulk modulus were 2.7,172.1 and 59.3 GPa, Co2Sc has the strongest resistance to volume change characteristics. The shear modulus of Co Sc, Co2Sc and Co Sc2 are 72.7, 70.1 and 20.9 GPa, respectively, and Co Sc has a relatively high stiffness. Co Sc B / G <1.75 for the brittle material, and Co2Sc, Co Sc2 B / G were 2.46, 2.84 for the plastic material.