Study On The Re-Pentaphosphate Crystal Used As The Standardized Sample For The Electron Probe Analysis

Abstract

Fifteen rare-earth pentaphosphates crystals (see table) were prepared by using the evaporation solution method ,which can be used as the standard sample in electron probe quantitative analysis of rare-earth minerals. Chemical analysis has been made for the composition of the samples and theoretic values . According to Boyd’s method,their homogeneity of element distribution and stability under the irradiation of electron beam were carefully invertigated using ModelEMX-SM7 electron probe.The results indicate that under the normal experiment conditions the homogeneity and stability of the samples are qualified. The inconductive samples were also studied to determine the effects of accelerating voltage,electron beam density (diameter of electron beam, beam current),irradiating time of electron beam and the thickness of evaporation film on the sample current and the stability of numbering. The results show that under the normal operating conditions (accelerative voltage 15KV, sample current 2×10-8A ,diameter of electron beam 4-5um)both sample current and numbering are stable within 5 min when the thickness of evaporation film is about 300 .