Xing Zhang 1, Shuiyuan Yang *1, He Zhao2, Shaoyong Jiang1, 3, 4, Ruoxi Zhang1, Jing Xie5
1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan
430074, China
2. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China
3. Faculty of Earth Resources and Collaborative Innovation Center for Scarce and Strategic Mineral Resources, China
University of Geosciences, Wuhan 430074, China
4. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University,
Nanjing 210093, China
5. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China
ABSTRACT: The effect of operating conditions on the time-dependent X-ray intensity variation is of great importance for the optimal EPMA conditions for accurate determinations of various elements in carbonate minerals. Beam diameters of 0, 1, 2, 5, 10, 15, and 20 μm, and beam currents of 3, 5, 10, 20, and 50 nA were tested. Ca, Mg, Zn, and Sr were found to be more sensitive to electron beam irradiation as compared to other elements, and small currents and large beam diameters minimized the timedependent X-ray intensity variations. We determined the optimal EPMA operating conditions for elements in carbonate: 10 μm and 5 nA for calcite; 10 μm and 10 nA for dolomite; 5 μm and 10 nA or 10 μm and 20 nA for strontianite; and 20 nA and 5 μm for other carbonate. Elements sensitive to electron beam irradiation should be determined first. In addition, silicate minerals are preferred as standards rather than carbonate minerals.
Effect of beam current and diameter on electron probe microanalysis of carbonate minerals.pdf