硅酸盐玻璃中的Na和K含量电子探针分析条件设定探讨  

Parameters of Electron Probe Microanalysis for Na and K in Silicate Glass

作　　者：李芳洲 李小犁 LI Fangzhou;LI Xiaoli(Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871

出　　处：《岩矿测试》2022年第2期161-173,共13页Rock and Mineral Analysis

基　　金：国家自然科学基金项目(41202032)。

摘　　要：含Ti硅酸盐玻璃在基础科学研究和应用技术开发上均有重要价值,亟需对其进行准确的成分分析,为进一步的科研工作提供重要的数据支撑。对玻璃进行电子探针分析时,由于样品的易损性和其中(Na和K)阳离子在电子束轰击下极易发生迁移和扩散,因此往往需要经过条件实验来确定合适的分析条件,确保样品在该条件下能够保持尽量稳定的状态,才能获得相对准确的定量分析结果。本文通过改变电子束束斑大小、电子束束流强度,以及待测元素特征X射线谱线峰位的计数时间,对高Na(NTS)和高K(KTS)的两类含Ti硅酸盐玻璃(Na_(2)O/K_(2)O-TiO_(2)-SiO_(2))进行系统分析,以获得其准确的元素化学组分,并为样品进一步的物理属性研究提供重要参考。本文研究表明,随着束斑大小增加、电流降低以及增加计数时间的变量改变,待测元素的定量分析结果大都表现出有规律的变化。并且,以最大限度接近样品理论含量为标准,确定在大束斑(80~100μm)、小电流(3nA或5nA)及适宜计数时间(10s、20s、30s和40s)条件下,可以对样品进行准确的定量分析。这与以往的玻璃分析条件有所不同,可能与本文样品的高Na、K以及Ti含量有关。与此同时,通过网格分析元素面分布建模,本文研究还揭示了待测样品中可能存在化学价键及相应晶体化学组构,这将为进一步的相关研究提供新思路和探索方向。BACKGROUND: The precise measurement for Na and K in silicate glass is usually difficult in electron probe microanalysis(EPMA). Ti-containing silicate glass has an important value in basic scientific research and application technology development, and it is urgent to carry out accurate composition analysis to provide important data support for further scientific research work. The glass is of amorphous form and damageable under electron bombardment. Moreover, the alkali Na and K elements can easily diffuse and migrate during the electron bombing. Therefore, it is often necessary to set the appropriate analysis conditions through conditional experiments to ensure that the sample can be kept as stable as possible under these conditions, so that relatively accurate quantitative analysis results can be obtained.OBJECTIVES: To determine the proper analytical conditions for Na and K analyses in the silicate glass.METHODS: Electron probe quantitative analyses for Na and K were performed in the synthetized silicate glass samples of NTS(Na;O-TiO;-SiO;) and KTS(K;O-TiO;-SiO;). By changing the probe diameter(10-100μm), beam current(3 nA, 5 nA and 10 nA) and count time(10 s, 20 s, 30 s and 40 s) orderly in a series of experiments, the optimal analytical conditions for accurate quantitative results were established. RESULTS: The results showed a systematic change with positive trend of Na, K, Si and Ti contents with probe diameter and count time increases, but a contrasting trend for beam current. In most cases, the conditions of larger probe diameter up to 80-100μm and lower beam current(3 nA or 5 nA) provided the highest Na or K content that maximumly approaches the normal value before synthesis. This was different from the previous glass analysis conditions, which may be related to the high Na, K and Ti content of the samples. In grid analysis for elemental map modeling, certain correlation(s) among Na, K, Si and Ti were revealed, which provided further perspectives for potential chemical bonds, i.e. crystallochemical st

关 键 词：硅酸盐玻璃 Na_(2)O-TiO_(2)-SiO_(2)体系 K_(2)O-TiO_(2)-SiO_(2)体系 电子探针 定量分析 网格分析 

分 类 号：P575.1[天文地球—矿物学]