深圳大学学报理工版

基于密度泛函理论的VASP(Vienna ab-initio simulation package)软件包进行第一性原理计算,研究压力状态下Al7Cu2Fe相的能带和各向异性变化情况.结果表明,在0～50 GPa的压力范围内Al7Cu2Fe相具有金属性,且压力有助于提高能带中原子轨道的扩展性.Al7Cu2Fe相的(100)和(010)晶面的弹性各向异性随着压力升高而增强,而(11^-0)晶面的弹性各向异性随着压力的升高呈波动上升趋势.基于准谐德拜模型,研究Al7Cu2Fe相的体积模量、德拜温度、热容和热膨胀系数随温度和压力的变化情况.结果表明,外加压力和温度对Al7Cu2Fe相热力学性质的影响是相反的.外加压力能有效提升Al7Cu2Fe相的体积模量和德拜温度,而温度升高会导致体积模量和德拜温度降低.Al7Cu2Fe相的热容和热膨胀系数在温度和压力下的变化规律基本一致.

The band structures and elastic anisotropy of Al7Cu2Fe phase under various pressures are studied by using the Vienna ab-initio simulation package(VASP)based on density functional theory. The results show that Al7Cu2Fe phase is still metallic in the pressure range of 0 to 50 GPa and the pressure can improve the expansion of atomic orbital in the energy band. The elasti anisotropy in(100)and(010)planes of Al7Cu2Fe phase enhances with the increase of pressure, while the elasti anisotropy in(11^-0)planes shows a fluctuating upward trend from 0 GPa to 50 GPa. Based on the quasi-harmonic Debye model, the changes of bulk modulus(B), Debye temperature(ΘD), heat capacity(Cv and Cp)and thermal expansion coefficient(α)of Al7Cu2Fe phase with pressure and temperature are studied. The effects of applied pressure and temperature on thermodynamic properties of the Al7Cu2Fe phase is opposite. The values of B and ΘD decrease with temperature and increase with the pressure. In addition, the variation trends of Cv, Cp and α under pressure and temperature are basically the same.

引言
1 计算方法
2 结果与分析
3 结论

图1 Al7Cu2Fe相的晶体结构<br/>Fig.1 The structure model of Al7Cu2Fe phase

图1 Al7Cu2Fe相的晶体结构
Fig.1 The structure model of Al7Cu2Fe phase

图2 不同压力下Al7Cu2Fe相的能带图<br/>Fig.2 The band structures of Al7Cu2Fe phase at 0 and 50 GPa

图2 不同压力下Al7Cu2Fe相的能带图
Fig.2 The band structures of Al7Cu2Fe phase at 0 and 50 GPa

表1 Al7Cu2Fe相的弹性常数Cij及弹性模量随压力的变化情况<br/>Table 1 The elastic constants and elastic moduli of Al7Cu2Fe phase under different pressuresGPa

表1 Al7Cu2Fe相的弹性常数Cij及弹性模量随压力的变化情况
Table 1 The elastic constants and elastic moduli of Al7Cu2Fe phase under different pressuresGPa

表2 Al7Cu2Fe相在不同压力下的剪切各向异性因子和各向异性指数<br/>Table 2 The shear anisotropic factors and universal elastic anisotropy index of Al7Cu2Fe phase under different pressure

表2 Al7Cu2Fe相在不同压力下的剪切各向异性因子和各向异性指数
Table 2 The shear anisotropic factors and universal elastic anisotropy index of Al7Cu2Fe phase under different pressure

图3 Al7Cu2Fe相的体积模量随温度和压力的变化情况<br/>Fig.3 B for Al7Cu2Fe phase at different temperatures and pressures

图3 Al7Cu2Fe相的体积模量随温度和压力的变化情况
Fig.3 B for Al7Cu2Fe phase at different temperatures and pressures

图4 压力和温度对Al7Cu2Fe相德拜温度的影响<br/>Fig.4 The variation trend of ΘD of Al7Cu2Fe phase at different temperatures and pressures

图4 压力和温度对Al7Cu2Fe相德拜温度的影响
Fig.4 The variation trend of ΘD of Al7Cu2Fe phase at different temperatures and pressures

图5 热容随温度和压力的变化情况<br/>Fig.5 Cv and Cp of Al7Cu2Fe phase as a function of temperature and pressure

图5 热容随温度和压力的变化情况
Fig.5 Cv and Cp of Al7Cu2Fe phase as a function of temperature and pressure

图6 热膨胀系数α随温度和压力的变化情况<br/>Fig.6 α of Al7Cu2Fe phase as a function of temperature and pressure

图6 热膨胀系数α随温度和压力的变化情况
Fig.6 α of Al7Cu2Fe phase as a function of temperature and pressure

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备注

引言

1 计算方法

2 结果与分析

3 结论

期刊信息

备注

引言

1 计算方法

2 结果与分析

3 结 论

期刊信息

3 结论