HgO-HI-H_2O体系HgI_2晶体分形结构的生长模拟  

Growth and Smulation of HgI_2 Crystal Fractal Structures in the HgO-HI-H_2O System

作　　者：李俊英[1] 许岗[1] 张延京[1] 杨丛笑[1] 郭炎飞 LI Junying XU Gang ZHANG Yanjing YANG Congxiao GUO Yanfei(School of Materials and Chemical Engineering,Xi＇an Technological Universit)

机构地区：[1]西安工业大学材料与化工学院,西安710021

出　　处：《西安工业大学学报》2017年第2期134-138,共5页Journal of Xi’an Technological University

基　　金：陕西省教育厅科研计划项目(15JS040);西安工业大学省级重点实验室开放基金(ZSKJ201414)

摘　　要：为探究HgO-HI-H_2O体系中HgI_2晶体的分形结构/枝晶的生长条件及其生长机理,通过控制Hg^(2+)∶I-摩尔比为1∶7~1∶2间配制溶液,在氧化铟锡玻璃(ITO)上等温溶剂挥发生长了HgI_2晶体.采用津岛紫外-可见分光光度计分析枝晶溶液体系中存在的生长单元;利用LEICA-DM2500P偏光显微镜观察晶体形貌变化,确定分型结构的生长工艺条件;采用二维扩散限制凝聚理论(DLA)对比理论计算与实际枝晶的分型维数,分析枝晶的生长机理.研究结果表明:HgO-HI-H_2O体系中晶体生长单元为HgI_2分子;在[Hg^(2+)]∶[I^-]≤1∶6时,生长形貌为枝晶;在1∶6~1∶3间,晶体形貌为树枝晶与四方晶共存;离子比为标准计量时,生长形貌为四方晶.模拟[Hg^(2+)]∶[I-]=1∶7时的树枝晶形貌与实际晶体形貌非常符合,分形维数分别为1.48和1.45,表明远离平衡条件下,树枝晶是由分子布朗运动形成,其形貌受到分子扩散影响。In order to explore the growth conditions and growth mechanism of fractal structure in HgOHI-H_2O solution,HgI_2 crystal was grown on ITO by means of isothermal solvent evaporation method with the ratio of Hg^2＋∶I^-（mol ratio）ranging from 1∶7 to 1∶2,repectively.The changes of crystal morphology was observed by LEICA-DM2500 Ppolarized microscope.The growth units in the dendritic crystal solution was investigated using UV-VIS spectrophotometer.Matlab software was used to simulate the crystal morphology according to the theory of two-dimensional Diffusion-Limited Aggregation（DLA）.The results reveal that growth morphology is dendrite while[Hg^2＋]∶[I^-]≤1∶6,it is tetragonal grain while[Hg^2＋]-[I^-]=1∶2.The growth unit in solution of[Hg^2＋]∶[I^-]≤1∶6 is HgI_2 molecules.The simulation of crystal morphology is consistent to the actual crystal,which the fractal dimension is 1.48 and 1.45,respectively.It can be proved that the formation of dendrite crystal derives from Brownian motion of molecules,which is controlled by molecules diffusion mechanism.

关 键 词：碘化汞 枝晶 分形维数 扩散限制凝聚理论 

分 类 号：TN304.25[电子电信—物理电子学] O78[理学—晶体学]