掺杂原子对α-Cr₂O₃结构稳定性和电子特性的第一性原理研究

First-Principle Study of Doping Atoms Effects on Structural Stability and Electronic Properties of α-Cr₂O₃ Oxide

摘要: 本文采用第一性原理研究了掺杂原子对α-Cr₂O₃结构稳定性和电子特性的影响。研究结果表明Fe、Mo、Nb、Ni、Mn、Al、Si掺杂于α-Cr₂O₃复合体系的结合能均为负值，这些元素构成的α-Cr₂O₃复合氧化物均具有稳定的结构，尤其Nb的作用最为明显。吉布斯自由能来看，掺杂原子后α-Cr₂O₃复合体系结构稳定性在200~1000 K温度范围内，随着温度的升高结构稳定性逐步增强，尤以Ni和Si最为明显。由布居数和态密度分析了复合体系α-Cr_1.5M_0.5O₃的电化学活性，计算结果来看Mo和Al能使α-Cr₂O₃构成的复合氧化物的带隙宽度稍微增加，而Si和Mn则使α-Cr₂O₃的带隙宽度变窄，即Mo和Al能提高α-Cr_1.5Mo_0.5O₃和α-Cr_1.5Mo_0.5O₃复合氧化物的电子化学稳定性。

Abstract: The structural stability and electronic property of α-Cr_1.5M_0.5O₃ with doping atoms are studied by first-principle calculations. The cohesive energy of α-Cr₂O₃ with Fe, Mo, Nb, Ni, Mn, Al and Si elements indicates that Nb, Al, Mo and Mn atoms are effective for improving the binding ability of α-Cr₂O₃ , especially Nb in α-Cr₂O₃ oxide. Gibbs free energy proves that these doping atoms’ solid solution in α-Cr₂O₃ makes the structure more stable at the temperature range of 200 - 1000 K, especially Ni and Si in α-Cr₂O₃ oxide. Compared with the band gap width of α-Cr_1.5M_0.5O₃ (M = Cr, Fe, Mo, Nb, Ni, Mn, Al, Si), Mo and Al are elements which are effective for increasing band gap width of α-Cr_1.5M_0.5O₃, namely Mo and Al can make the structure more electrochemically stable.