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

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-Cr1.5M0.5O3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-Cr1.5Mo0.5O3和α-Cr1.5Mo0.5O3复合氧化物的电子化学稳定性。

The structural stability and electronic property of α-Cr1.5M0.5O3 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-Cr1.5M0.5O3 (M = Cr, Fe, Mo, Nb, Ni, Mn, Al, Si), Mo and Al are elements which are effective for increasing band gap width of α-Cr1.5M0.5O3, namely Mo and Al can make the structure more electrochemically stable.