Departamento de Física de la Materia Condensada , GIyA, CACCNEA, Instituto de Nanociencia y Nanotecnologı́a, CNEA-CONICET , 1650 San Martin , B1650 Buenos Aires , Argentina.
Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Ciudad Universitaria , Pab. II, Buenos Aires C1428EHA , Argentina.
Inorg Chem. 2018 May 7;57(9):4989-4996. doi: 10.1021/acs.inorgchem.7b03231. Epub 2018 Apr 26.
In this work we present a systematic computational study of the structural and magnetic properties of a layered family of Co(II) hydroxichlorides, obeying to the general formula Co(OH)Cl (HO) . This solid contains both octahedral and tetrahedral cobalt ions, displaying a complex magnetic order arising from the particular coupling between the two kinds of metallic centers. Here, supercells representing concentrations of 12, 20, and 40% of tetrahedral sites were modeled consistently with the compositions reported experimentally. Our simulations show that the two types of cobalt ions tend to couple antiferromagnetically, giving rise to a net magnetic moment slightly out of the plane of the layers. The band gap reaches its minimum value of 1.4 eV for the most diluted fraction of tetrahedral Co(II) sites, going up to 2.2 eV when the content is 40%. Moreover, our results suggest that the presence of interlayer water stabilizes the material and at the same time strongly modifies the electronic environment of tetrahedral Co(II), leading to a further drop of the band gap. To our knowledge, this is the first theoretical investigation of this material.
在这项工作中，我们对遵循通式 Co(OH)Cl(HO)的一系列层状 Co(II)氢氯化物的结构和磁性进行了系统的计算研究。该固体包含八面体和四面体钴离子，由于两种金属中心之间的特殊耦合，显示出复杂的磁有序。在这里，用实验报告的组成一致地模拟了代表四面体位置浓度为 12%、20%和 40%的超胞。我们的模拟表明，两种类型的钴离子倾向于反铁磁耦合，导致净磁矩略微偏离层的平面。当四面体 Co(II)位的含量为 40%时，带隙达到最小 1.4 eV，当四面体 Co(II)位的含量为 40%时，带隙达到最大 2.2 eV。此外，我们的结果表明，层间水的存在稳定了材料，同时强烈改变了四面体 Co(II)的电子环境，导致带隙进一步降低。据我们所知，这是对该材料的首次理论研究。
