Microanalysis of Glass Containing Alkali Ions
Microanalysis of Glass Containing Alkali Ions
复制标题
含碱离子玻璃的微量分析
DOI：
10.1007/s006040050050
复制
发表时间：
2000
影响因子：
5.7
通讯作者：
K. Jurek
中科院分区：
文献类型：
--
作者：
O. Gedeon;V. Hulínský;K. Jurek
在含有几乎所有可能的碱离子(Na、K、Rb、Cs)的玻璃上，研究了EPMA过程中与碱离子迁移有关的常见问题。以纯硅酸盐玻璃为原料，在铂坩埚中熔化制备了二元二氧化硅玻璃。这些玻璃是用酒精仔细抛光的，以防止表面被水腐蚀，并储存在真空中。样品被覆盖了大约30纳米厚的碳层，并暴露在直径为100 m的50 μkeV电子束中。结果表明，所有碱性离子都在电子束作用下发生迁移，但迁移速率与电流密度有关。在所有情况下，衰变曲线(特征X射线强度与时间的关系)形状相似。衰减曲线显示出两种输运模式，第一种为线性输运模式，第二种为指数输运模式。在一段被称为潜伏期的时间之后，第一个运移机制进入了快速的碱迁移。一般情况下，碱性离子越大，周期越长。研究发现，即使是大的Rb和Cs离子也会以与钠离子和钾离子相同的机制迁移到玻璃内部。而对于K、Rb、Cs离子，在合适的实验条件下观察到了潜伏期，而含Na的二元玻璃没有观察到的潜伏期。除了二元Na_2O- + -SiO_2玻璃外，还可以找到可靠定量电子探针的合适实验条件。
The common problems connected with alkali ion migration during EPMA were studied on glasses containing nearly all possible alkali ions (Na, K, Rb, Cs). Binary silica glasses were prepared by melting from a very pure batch in Pt crucible. The glasses were carefully polished using alcohol to prevent surface corrosion by water and they were stored in vacuum. The specimens were coated with carbon layers approximately 30-nm thick and exposed to a 50- keV electron beam of 100 μm diameter. It was found that all alkali ions migrate under the electron beam, but the rate of the migration depends on the current density. The decay curves (characteristic X-ray intensity versus time) are similar in shape in all cases. The decay curve shows two transport regimes, the first being linear-like, the second being the exponential-like. The first transport regime busts into the rapid alkali migration after a time known as the incubation period. The period is in general longer for the larger-alkali ions size. It was found that even large rubidium and caesium ions migrate inside the glass with the same mechanism as sodium and potassium ions. While for K, Rb, and Cs ions the incubation periods were observed under the suitable experimental conditions, binary glass containing Na exhibits no observable incubation period. Except for the binary Na2O + SiO2glass, the suitable experimental conditions for reliable quantitative EPMA can be found.