XIAO Liuping, XIE Lei, ZHOU Jiaolian, LI Yaxin, XIE Lifang
The accurately determination of impurity elements content in high-purity cesium is crucial for guiding the production impurity removal,improving the material performance,and ensuring the stable operation of national defense,military industry,satellite navigation and other fields.Due to the high chemical reactivity of cesium(it can be rapidly oxidized upon contact with air and it is explosive when exposed to liquid solvents),its sampling and decomposition pose severe challenges.In this study,the sampling was conducted in an argon atmosphere within an oxygen-isolated glove box.Based on the characteristic of cesium that its melting point (28.5 ℃) is slightly higher than room temperature but lower than hand temperature,the solid samples were melted into liquid using hand warmth as a heat source.A pipette was used for quantitative liquid transfer,overcoming the difficulty of sampling high-viscosity solids.The wall-hung samples were placed in open air for over 10 h.Utilizing the properties of easy oxidation for cesium,susceptibility to hydration for cesium oxides and deliquescence for cesium hydroxides,a three-stage gas-solid reaction chain of "oxidation→hydration→deliquescence" was constructed with oxygen and water vapor as reactants to achieve gradual passivation and mild decomposition.Based on this,a method for determination of 9 impurity elements in high-purity cesium,including lithium,sodium,potassium,calcium,magnesium,iron,aluminum,lead and rubidium,by inductively coupled plasma atomic emission spectrometry(ICP-AES) was established.To address the coupled ionization and physical interference effects caused by cesium matrix,a strategy was adopted that primarily used the matrix matching method(for correcting lithium,sodium,potassium,calcium,magnesium,iron,aluminum,lead) and supplemented by the standard addition method(for correcting rubidium).The calibration curves had good linear relationships,and the correlation coefficients (r) were all not less than 0.999 6.The limit of detection ranged from 0.000 001% to 0.000 042%,and the limit of quantification ranged from 0.000 01% to 0.000 42%.The content of 9 impurity elements in actual and synthetic high-purity cesium samples were determined according to the experimental method.The relative standard deviations(RSD,n=5) of the determination results were between 0.86% and 9.5%,and the recoveries ranged from 94.9% to 103% (except rubidium).The content of rubidium in sample was determined by inductively coupled plasma mass spectrometry(ICP-MS) and compared with the experimental method.It was found that the measurement results of two methods were basically consistent.
