Theory analysis and vestigial information of surface relaxation of natural chalcopyrite mineral crystal  

天然黄铜矿矿物晶体的表面弛豫信息与理论分析(英文)

作　　者：文书明[1] 邓久帅[1] 先永骏[1] 刘丹[1] 

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第3期796-803,共8页中国有色金属学报（英文版）

基　　金：Project(u0837602) supported by the Key Program of the National Natural Science Foundation of China;Project(2010J056) supported by the Natural Science Foundation of Education Department of Yunnan Province,China;Projects(2009113,2011464) supported by the Analysis and Testing Foundation of Kunming University of Science and Technology;Project(41118011) supported by the Excellent Doctoral Dissertation to Cultivate Foundation of Kunming University of Science and Technology

摘　　要：X-ray diffraction was used to measure the unit cell parameters of chalcopyrite crystal.The results showed that the chalcopyrite crystal is perfect,and the arrangement of its atoms is regular.A qualitative analysis of molecular mechanics showed that surface relaxation causes the chalcopyrite surface to be sulfur enriched.Atomic force microscope（AFM） was used to obtain both a microscopic three-dimensional topological map of chalcopyrite surface and a two-dimensional topological map of its electron cloud.The AFM results revealed that the horizontal and longitudinal arrangements of atoms on the chalcopyrite surface change dramatically compared with those in the interior of the crystal.Longitudinal shifts occur among the copper,iron and sulfur atoms relative to their original positions,namely,surface relaxation occurs,causing sulfur atoms to appear on the outermost surface.Horizontally,AFM spectrum showed that the interatomic distance is irregular and that a reconstruction occurs on the surface.One result of this reconstruction is that two or more atoms can be positioned sufficiently close so as to form atomic aggregates.The lattice properties of these models were calculated based on DFT theory and compared with the experimental results and those of previous theoretical works.On analyzing the results,the atomic arrangement on the（001） surface of chalcopyrite is observed to become irregular,S atoms move outward along the Z-axis,and the lengths of Cu—S and Fe—S bonds are enlarged after geometry optimization because of the surface relaxation and reconstruction.The sulfur-rich surface and irregular atomic aggregates caused by the surface relaxation and reconstruction greatly influence the bulk flotation properties of chalcopyrite.通过XRD测定黄铜矿晶体的晶胞参数,表明黄铜矿结晶完整,内部原子排列规则。通过分子力学定性分析,指出黄铜矿表面弛豫出现表面富硫现象。采用AFM获得黄铜矿表面的三维微观结构拓扑图和表面电子云分布二维拓扑图。AFM分析测试结果表明,黄铜矿表面原子的纵向和横向排列与晶体内部相比发生了很大变化。纵向上,铜、铁和硫原子相对于原来的位置发生位移,即发生了表面弛豫,弛豫的结果使得硫原子位于表面的最外区域。横向上,AFM图谱显示原子间距不规则,表面发生重构,重构的结果使得部分两个或更多个原子靠近,形成原子聚集体。采用基于密度泛函理论的总体能量平面波超软赝势法,电子交换关联能结合广义梯度近似形式,对晶胞进行优化。结果表明,(001)面表面原子排布变得不规则,表面硫原子沿Z轴轴向外移,铜硫键和铁硫键键长增加,晶胞体积膨胀,表面发生弛豫,晶体结构发生重构。这种表面弛豫和重构导致的富硫表面和不规则的原子聚集对浮选具有重要影响。

关 键 词：CHALCOPYRITE surface relaxation RECONSTRUCTION sulfur-rich surface 

分 类 号：P573[天文地球—矿物学]