Metastable Layered Cobalt Chalcogenides from Topochemical Deintercalation.
Metastable Layered Cobalt Chalcogenides from Topochemical Deintercalation.
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DOI：
10.1021/jacs.6b10229
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发表时间：
2016-12
影响因子：
15
通讯作者：
Xiuquan Zhou;B. Wilfong;H. Vivanco;J. Paglione;C. Brown;E. Rodriguez
中科院分区：
文献类型：
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作者：
Xiuquan Zhou;B. Wilfong;H. Vivanco;J. Paglione;C. Brown;E. Rodriguez
我们提出了一种通过热力学稳定相的局部化学脱嵌来合成亚稳层状材料的一般策略。通过对脱嵌反应的动力学控制，我们分别从起始化合物KCo2Se2和KCo2S2出发，合成了两种假想的具有反PbO结构的亚稳态化合物CoSe和CoS。研究了这些新的层状硫系化合物的热稳定性、X射线和中子衍射的晶体结构、磁化率、磁化强度和电阻率，发现CoS和CoS都是居里温度接近10K的弱巡游铁磁体。由于层间的弱van der Waals力，CoS被发现是进一步插入客体物种如Li-乙二胺的合适宿主。根据第一性原理计算，我们解释了为什么钴硫化物是铁磁体，而不是像它们的铁类似物那样是超导体。对计算的电子态密度的成键分析既解释了它们的相稳定性，也预测了我们的去嵌入技术的局限性。我们的结果对合理设计新型功能材料的二维构件具有广泛的指导意义。
We present a general strategy to synthesize metastable layered materials via topochemical deintercalation of thermodynamically stable phases. Through kinetic control of the deintercalation reaction, we have prepared two hypothesized metastable compounds, CoSe and CoS, with the anti-PbO type structure from the starting compounds KCo2Se2 and KCo2S2, respectively. Thermal stability, crystal structure from X-ray and neutron diffraction, magnetic susceptibility, magnetization, and electrical resistivity are studied for these new layered chalcogenides; both CoSe and CoS are found to be weak itinerant ferromagnets with Curie temperatures close to 10 K. Due to the weak van der Waals forces between the layers, CoSe is found to be a suitable host for further intercalation of guest species such as Li-ethylenediamine. From first-principles calculations, we explain why the Co chalcogenides are ferromagnets instead of superconductors as in their iron analogues. Bonding analysis of the calculated electronic density of states both explains their phase stability and predicts the limits of our deintercalation technique. Our results have broad implications for the rational design of new two-dimensional building blocks for functional materials.