基于红外和拉曼光谱的氟碳铈矿热稳定性研究  

Experimental study on the thermal stability of Bastnaesite and its hydroxyl group behaviors based on IR and Raman analysis

作　　者：石羽钧 张家晟 何超 李林 SHI Yujun;ZHANG Jiasheng;HE Chao;LI Lin(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Beijing),Beijing 100083;School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083100083;Institute of Earth Sciences,China University of Geosciences(Beijing),Beijing;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083)

机构地区：[1]地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学(北京)能源学院,北京100083 [3]中国地质大学(北京)科学研究院,北京100083 [4]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《光散射学报》2024年第4期399-409,共11页The Journal of Light Scattering

基　　金：国家级大学生创新创业训练计划支持项目(202311415084);中国地质大学(北京)大学生创新创业训练计划项目资助(项目号:202311415084)

摘　　要：碳酸盐是地球深部碳循环的重要载体和研究对象。造山带和大陆边缘碳酸岩型稀土矿床中最常见矿石矿物—氟基稀土碳酸盐(氟碳铈矿)与羟基稀土碳酸盐晶体结构相似,常以不同比例形成类质同象。本文综合运用高温氘代示踪、单晶X射线衍射、红外和拉曼光谱分析技术,从实验矿物学角度厘定了氟碳铈矿发生氘代反应的条件,研究了氟碳铈矿在不同温度和氘代过程中的结构状态、热稳定性和其表面氟基被羟基置换的条件。结果表明,氟碳铈矿在548 K和280 ml/min的CO_(2)气流量条件下发生氘代反应;在293 K~548 K范围内增温过程中结构型不变,在573 K、598 K时发生部分分解;将氘代实验后的样品在实验室常温压下放置6个月后,测得样品表层氟基和羟基发生类质同象置换,形成含羟基氟碳铈矿,且表面有吸附水。氟碳铈矿是碳、氟(-羟基)和稀土元素在地球浅部成矿的产物,本实验结果对于理解碳、水、氟和稀土元素组合的地球化学循环与富集机制具有重要意义。Carbonates are important carriers and subjects of study in the deep carbon cycle of the Earth.Fluorine-bearing rare earth carbonates(such as bastn site),which are common ore minerals in rare earth deposits within orogenic belts and continental margins,have similar crystal structures to hydroxyl-bearing rare earth carbonates and often form solid solutions in varying proportions.This research employs a combination of high-temperature deuterium tracer experiments,single-crystal X-ray diffraction,infrared,and Raman spectroscopy to define the conditions under which deuterium substitution occurs in bastn site from an experimental mineralogy perspective.It investigates the structural state,thermal stability,and conditions for surface fluorine substitution by hydroxyl groups in bastn site at different temperatures and during the deuterium substitution process.The results show that bastn site undergoes deuterium substitution at 548 K and under a CO_(2)gas flow rate of 280 ml/min.The structural type remains unchanged during temperature increases in the range of 293 K to 548 K,but partial decomposition occurs at 573 K and 598 K.After storing the samples at laboratory ambient temperature and pressure for six months following the deuterium substitution experiment,it was found that the surface fluorine and hydroxyl groups underwent isomorphous replacement,forming hydroxy-fluorocarbonates,and that there was adsorbed water on the surface.Bastnaesite are products of mineralization involving carbon,fluorine(-hydroxyl),and rare earth elements in the Earth’s near-surface environment.The results of this experiment are significant for understanding the geochemical cycling and enrichment mechanisms of carbon,water,fluorine,and rare earth elements.

关 键 词：氟碳铈矿 氘代反应 热稳定性 羟基化 光谱学分析 

分 类 号：O433[机械工程—光学工程] P575[理学—光学]