Density Functional Theory of New Double “A” Layer MAX Phase V2Ga2C under High Pressure
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摘要: 基于密度泛函理论的第一性原理,研究了压强对双“A”层MAX相V2Ga2C晶体结构、弹性和电子性质的影响,并利用玻恩稳定准则预测了V2Ga2C力学稳定状态下的压强范围。计算结果表明:在0~70 GPa下,V2Ga2C的晶体结构处于力学稳定状态;随着压强的增大,V2Ga2C的晶格常数和体积均有不同程度的缩小,a轴随压强的增大收缩得最快,晶胞体积收缩了24%左右;随着压强的增加,V2Ga2C材料的维氏硬度从0 GPa压强下的18.23 GPa减小为70 GPa压强下的2.30 GPa,在20.15 GPa时从脆性材料转变为韧性材料;V2Ga2C的态密度和能带结构等电子性质随压强的变化较小,即压强对V2Ga2C的电子性质影响不大。Abstract: The structural, elastic and electronic properties of double “A” layer MAX phase V2Ga2C under high pressure were studied by the first-principles calculations of density functional theory, and the stable state of V2Ga2C was predicted by using the Born stability criteria. The results show that V2Ga2C crystal structure at the state of mechanical stability within the pressure range of 0–70 GPa. With the increase of pressure, the lattice parameters and volumes of V2Ga2C decreased. V2Ga2C is more compressible in the a-axis direction than c-axis direction, and the volume shrinks by about 24%. With increasing pressure, Vickers hardness of V2Ga2C material decreased from 18.23 GPa (0 GPa) to 2.30 GPa (70 GPa), and from brittle material transform into ductile material at 20.15 GPa. With the change of pressure, the electronic properties have changed slightly such as density of states and band structures, which have almost no effect on the electronic properties of V2Ga2C.
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Key words:
- MAX phase /
- V2Ga2C /
- high pressure /
- mechanical stability /
- elastic property /
- electronic property
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表 1 不同压强下V2Ga2C的弹性常数
Table 1. Pressure dependences of elastic constants for V2Ga2C
Pressure/GPa C11/GPa C33/GPa C44/GPa C12/GPa C13/GPa 0 275.07 309.04 88.92 65.69 48.31 10 325.89 437.85 103.70 79.38 101.23 20 392.18 492.57 112.70 113.70 122.66 30 475.27 582.90 99.80 176.94 174.81 40 462.17 636.80 103.00 156.69 180.10 50 524.87 696.25 51.41 228.45 221.66 60 558.67 743.34 29.53 220.05 219.34 70 640.36 854.90 4.53 280.99 275.36 80 618.66 892.67 −84.84 305.13 305.24 -
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