Yankuang ceshi (Mar 2022)
Parameters of Electron Probe Microanalysis for Na and K in Silicate Glass
Abstract
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 (Na2O-TiO2-SiO2) and KTS (K2O-TiO2-SiO2). By changing the probe diameter (10-100μm), beam current (3nA, 5nA and 10nA) and count time (10s, 20s, 30s and 40s) 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 (3nA or 5nA) 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 structure of the sample. CONCLUSIONS A larger probe diameter of 100μm and lower beam current of 3-5nA for Na and K analyses in silicate glass are recommended for optimum analysis.
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