彩钼铅矿电子结构和暴露面预测的第一性原理计算研究

First-Principles Study on Electronic Properties and Commonly Exposed Surfaces of Wulfenite Crystal

彩钼铅矿是重要的钼氧化矿,同时富含钼和铅两种有价元素,具有重要的综合利用价值。基于密度泛函理论,采用第一性原理研究了彩钼铅矿的电子结构,从晶面未饱和键密度和表面能角度对彩钼铅矿的暴露面进行了预测,并与彩钼铅矿纯矿物的X射线衍射分析结果(XRD)进行了对比。结果表明,理想彩钼铅矿属直接带隙p型半导体,费米能级附近主要要由Mo的4d~5轨道、O的2p~4轨道和小部分的Pb 6s~2轨道电子贡献,Mo—O键重叠布居较大,在MoO_4四面体基团内部沿着Mo—O键电子云分布较均匀,表现出较强的共价性,不易断裂。Pb—O键重叠布居较少,沿Pb—O键没有明显电子云分布,说明Pb—O键极有可能是以离子键键合或者不成键的形式存在。彩钼铅矿的{112}面和{001}面由于更低的表面能、更小的断裂键密度和更大的层间距,是彩钼铅矿的最可能暴露面,这一结果与XRD的分析结果相一致,也验证了第一性原理计算结果的准确性。上述结论有助于深入了解彩钼铅矿的物化性质,并为相关浮选机理的研究提供参考。

Wulfenite is an important molybdenum oxide mineral,which has important comprehensive utilization value because of its high content of molybdenum and lead element.Based on density functional theory,first principles study on electronic properties of wulfenite crystal has been conducted,and the commonly exposed surfaces of wulfenite crystal have been predicted from the perspective of anisotropic surface broken bonds and surface energies,respectively,and the predictions have also been compared with the X-ray diffraction analysis(XRD)of pure wulfenite.The results indicate that the perfect wulfenite is of direct bandgapp-type semiconductor,and the Fermi levels are mainly contributed by the 4d5 orbital of Mo,the 2p4 orbital of O and slightly by the 6s2 orbital of Pb.the Mo-O bond has a large overlapping Mulliken population,and the electron clouds are mainly distributed along Mo-O bonds which indicates strong covalent bonding and hard to break.While the Pb-O bond has a smaller Mulliken population,and no obvious electron clouds are found along Pb—O bonds,which indicates ionic bonding or no bonding.Based on the calculations,the{112}surfaces and{001}surfaces are expected to be the most common cleavage surfaces due to their lower surface energies,smaller broken bond densities,and larger interlayer spacings than other surfaces,and the results are consistent with the X-ray diffraction(XRD)observations,which verify the accuracy of the first-principles calculation.The above conclusions will help to understand the physicochemical properties of wulfenite,and provide references for related flotation mechanism research.