混合酸制备四氟化硅气体用于硅同位素测量

Preparation of SiF_4 Gas by Mixture Acid Method and Its Application for Determination of Si Isotopic Abundance Ratios

1引言 在自然界中,硅元素有3种稳定同位素28Si,29Si和30Si,丰度分别为92.23%,3.68%和3.09%。准确测量硅的摩尔质量,需准确测量硅的3种同位素的丰度值。目前,测量硅摩尔质量最佳的方法是采用SiF4气体测定硅同位素的丰度值,

To determine the isotope ratios of single crystal silicon,SiF4 gas was prepared by using the mixture acid method.After etching the single crystal silicon,the sample was dissolved with appropriate of HF and HNO3 mixture acid.BaSiF6 precipitation was obtained by adding BaCl2 solution to the silicon solution,and then BaSiF6 was decomposed into SiF4 gas.We measure the silicon isotope ratios of SiF4 sample by gas mass spectrometer.Some parameters were optimized in the chemical treatment.The sample was completely dissolved to yield of BaSiF6 precipi-tation.The result shows that the SiF4 samples are pure and the maximum errors among the SiF4 samples are no more than 0.2‰ for δ ^30Si and for δ ^29Si,and the standard deviation is no more than 0.1‰ for δ ^30Si and for δ ^29Si.