School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
J Chem Phys. 2010 Jan 14;132(2):024707. doi: 10.1063/1.3290815.
The Cu(I)-based delafossite structure, Cu(I)M(III)O(2), can accommodate a wide range of rare earth and transition metal cations on the M(III) site. Substitutional doping of divalent ions for these trivalent metals is known to produce higher p-type conductivity than that occurring in the undoped materials. However, an explanation of the conductivity anomalies observed in these p-type materials, as the trivalent metal is varied, is still lacking. In this article, we examine the electronic structure of Cu(I)M(III)O(2) (M(III)=Al,Cr,Sc,Y) using density functional theory corrected for on-site Coulomb interactions in strongly correlated systems (GGA+U) and discuss the unusual experimental trends. The importance of covalent interactions between the M(III) cation and oxygen for improving conductivity in the delafossite structure is highlighted, with the covalency trends found to perfectly match the conductivity trends. We also show that calculating the natural band offsets and the effective masses of the valence band maxima is not an ideal method to classify the conduction properties of these ternary materials.
基于铜（I）的水锌矿结构，Cu（I）M（III）O（2），可以在 M（III）位置上容纳广泛的稀土和过渡金属阳离子。已知二价离子对这些三价金属的替代掺杂比未掺杂材料中发生的掺杂产生更高的 p 型电导率。然而，对于在这些 p 型材料中观察到的电导率异常，当三价金属变化时，仍然缺乏解释。在本文中，我们使用密度泛函理论（针对强关联系统中的局域库仑相互作用进行了修正的 GGA+U）研究了 Cu（I）M（III）O（2）（M（III）=Al，Cr，Sc，Y）的电子结构，并讨论了异常的实验趋势。强调了 M（III）阳离子和氧之间的共价相互作用对于提高水锌矿结构中的电导率的重要性，发现共价趋势与电导率趋势完全匹配。我们还表明，计算自然能带偏移和价带最大值的有效质量不是分类这些三元材料传导特性的理想方法。
