论文标题
共取代的Bifeo3：第一原理的电子，铁电和热力学特性
Co-substituted BiFeO3: electronic, ferroelectric, and thermodynamic properties from first principles
论文作者
论文摘要
Bismuth铁素体Bifeo3是一种多性固体，由于铁电偏振会增强光生载体的分离，因此吸引了越来越多的注意力作为潜在的光催化材料。通过寻找途径来设计带隙和带路的动机，在保存或增强铁电特性的同时，我们研究了BICOXFE1 XO3固定溶液的热力学，电子和铁电特性，并使用密度的功能理论使用0 <x <0.13，使用密度的功能理论。我们表明，通过钴取代可以将带隙从2.9 eV降低到2.1 eV，同时增加了自发极化，这与与Fe阳离子相比，这与明显更大的CO的天生有效电荷有关。我们讨论了CO杂质之间的相互作用，该CO杂质非常有吸引力，并且会驱动CO的聚集，这是蒙特卡洛模拟所证明的。因此，相位将相位分为热力学优先，并且均匀的固体溶液只能以亚稳态形式存在，受到缓慢的阳离子扩散动力学的保护。最后，我们在适用于光催化的背景下讨论了具有相关氧化还原电位的纯和共取代的BifeO3的带对齐。
Bismuth ferrite, BiFeO3, is a multiferroic solid that is attracting increasing attention as a potential photocatalytic material, because the ferroelectric polarisation enhances the separation of photogenerated carriers. With the motivation of finding routes to engineer the band gap and the band alignment, while conserving or enhancing the ferroelectric properties, we have investigated the thermodynamic, electronic and ferroelectric properties of BiCoxFe1 xO3 solid solutions, with 0 < x < 0.13, using density functional theory. We show that the band gap can be reduced from 2.9 eV to 2.1 eV by cobalt substitution, while simultaneously increasing the spontaneous polarisation, which is associated with a notably larger Born effective charge of Co compared to Fe cations. We discuss the interaction between Co impurities, which is strongly attractive and would drive the aggregation of Co, as evidenced by Monte Carlo simulations. Phase separation into a Co-rich phase is therefore predicted to be thermodynamically preferred, and the homogeneous solid solution can only exist in metastable form, protected by slow cation diffusion kinetics. Finally, we discuss the band alignment of pure and Co-substituted BiFeO3 with relevant redox potentials, in the context of its applicability in photocatalysis.
