A first-principles study of the properties of four predicted novel phases of AlN
A first-principles study of the properties of four predicted novel phases of AlN
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DOI：
10.1016/j.jpcs.2016.12.032
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发表时间：
2017-05
影响因子：
4
通讯作者：
Ruike Yang;Chuanshuai Zhu;Q. Wei;Z. Du
中科院分区：
文献类型：
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作者：
Ruike Yang;Chuanshuai Zhu;Q. Wei;Z. Du
根据密度泛函理论（DFT），利用第一性原理计算了预测的四种新型AlN相（Pmn21-AlN、Pbam-AlN、Pbca-AlN和cmcm -AlN）的结构、弹性、热力学、电子和光学性质。这些相是用CALYPSO方法发现的，但尚未在实验中合成。这里我们预测它们的一些性质。分别用GGA-PBE和PBE0对其性能进行了分析。PBE0得到了精度更高的结果。Cmcm-AlN具有更好的塑性，其杨氏模量比pmn21 - aln、pam - aln和pbca - aln具有更清晰的各向异性。在较高温度下，德拜温度表现出较弱的温度依赖性，接近于一个恒定值。这四种新AlN相和wz-AlN的Dulong-Petit极限都在48jmol−1K−1左右，它们具有几乎相同的温度规律。带隙结构表明，四种AlN均为宽直接带隙半导体，带隙分别为5.95 eV （Pmn21-AlN）、5.99 eV （Pbam-AlN）、5.88 eV （Pbca-AlN）和5.59 eV （Cmcm-AlN）。其成键行为是共价键和离子键的结合。并详细计算了介质常数、折射率、反射率、吸收光谱、损耗光谱、电导率和拉曼光谱。四个相的等离子体频率均低于wz-AlN。
Structural, elastic, thermodynamic, electronic and optical properties of four predicted novel AlN phases (Pmn21-AlN,Pbam-AlN,Pbca-AlN andCmcm-AlN) are calculated using first-principles according to density function theory (DFT). These phases were found using the CALYPSO method but have not yet been synthesized experimentally. Here we predict some of their properties. The properties are analyzed by means of GGA-PBE and PBE0 respectively. The more precision results are obtained by PBE0.Cmcm-AlN owns better plasticity and it's Young's modulus has clearer anisotropy thanPmn21-AlN,Pbam-AlN andPbca-AlN. The Debye temperature, under higher temperature, shows weak temperature dependence and approach to a constant value. The Dulong-Petit limit of all four novel AlN phases andwz-AlN is about 48 J mol−1K−1and they have almost the same temperature law. The band structures show that the four AlN are the wide direct band gap semiconductors, which band gaps are 5.95 (Pmn21-AlN), 5.99 (Pbam-AlN), 5.88 (Pbca-AlN) and 5.59 eV (Cmcm-AlN). The bonding behaviors are the combination of covalent and ionic nature. The dielectric constants, refractive index, reflectivity, absorption, loss spectra, conductivity and Raman spectra are also calculated in detail. All four phases have a lower plasma frequency than of wz-AlN.