热液条件下锐钛矿晶体生长的实验  

Experimental Studies on Crystal Growth of Anatase under Hydrothermal Conditions

作　　者：丁兴[1,2] 何俊杰[3,4] 刘灼瑜 Ding Xing;He Junjie;Liu Zhuoyu(State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China;Key Laboratory of Mineralogy and Nietallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Cuangzhou 510640, China;College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China)

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院青藏高原地球科学卓越创新中心,北京100101 [3]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [4]中国科学院大学地球与行星科学学院,北京100049

出　　处：《地球科学》2018年第5期1763-1772,共10页Earth Science

基　　金：国家重点研究发展计划项目(No.2016YFC0600408);国家自然科学基金项目(No.41773054)

摘　　要：为了解金属离子生长成为热液矿石矿物的过程和机理,使用氟钛酸钾稀溶液在100MPa和200~400℃条件下开展了一系列等温不等时和等时变温实验.结果显示该热液条件下形成了不同形貌的锐钛矿.随着反应时间和温度的增加,锐钛矿由几十纳米生长至十几微米;10h以内的晶体生长速度远高于10h以后,相对高温下的晶体生长速度则高于低温,表明锐钛矿的热液生长与温度、过饱和程度密切相关.综合来看,粒子成核生长、定向附着和奥氏熟化先后控制了热液锐钛矿的生长,而金属在流体中的过饱和程度和溶解-沉淀过程则决定了其生长速度.因而锐钛矿的形态特征可用于指示其形成的温度、世代关系甚至含氟流体的演化历史.How metal mineral grows in hydrothermal fluids from a metal ion or metallic compound to the macrocrystals is one of the most fundamental problems in mineralogy and metallogeny.In this study,a series of non-isothermal and non-isochronic hydrolysis experiments of potassium titanium fluoride（K2 TiF6）solution were investigated at temperatures from 200 to 400℃and pressure of 100 MPa.The results show that anatases,with varied morphology,were synthetized in the hydrothermal conditions.With increasing reactive time and temperature,the anatase can grow up from dozens of nanometers to 10 micrometers or more.Remarkably,the anatases that were synthetized within 10 hor at higher temperatures exceeds those over 10 hor at lower temperatures in the rate of growth,which suggests the supersaturation level of Ti and temperature dependence on the crystal morphology,grain size and the rate of growth of the anatase.Generally speaking,classical nucleation and growth,oriented attachment,and Ostwald ripening are involved in the growth of the hydrothermal anatase,in which the supersaturation level of metal in hydrothermal fluids and dissolution-precipitation process are decisive to control the rate of anatase growth.Finally,we consider anatase as a typomorphic mineral that its morphology could be used to decipher the formation temperature,generation relationship of minerals,and even the evolution of F-bearing hydrothermal fluids.

关 键 词：热液 锐钛矿 晶体生长 定向附着 奥氏熟化 结晶学 

分 类 号：P571[天文地球—矿物学]