锗二次阴极-直流辉光放电质谱法测定高纯石英中9种杂质元素

锂、铍、硼、钠等作为高纯石英中的常见杂质元素,对产品的性能有重要影响,建立相应的测定方法至关重要。实验采用锗罩作为二次阴极,建立了直流辉光放电质谱法(dc-GDMS)测定高纯石英中锂、铍、硼、钠、镁、铝、硫、钛、铜等9种杂质元素的方法。所用锗罩的厚度为0.25 mm,罩上有4个尺寸为1 mm×8 mm的狭缝,每个狭缝间隔1 mm。实验还考察了放电参数对基体信号强度、信号稳定性、基体和锗罩信号比的影响。实验表明,当在1.3 mA/1 350 V的放电参数下,²⁸Si的信号强度可达1.3×10⁹ cps,放电稳定,硅、锗的信号比为1∶40。按照实验方法测定高纯石英样品中锂、铍、硼、钠、镁、铝、硫、钛、铜,结果的相对标准偏差(RSD,n=5)均在30%以内;还对比了锗罩、钽罩对高纯石英测定结果的影响,结果表明,由于钽罩中铜含量较大,导致铜测定结果差异较大以外,其余元素测定结果基本一致。采用锗罩测定高纯石英中杂质元素的检出限可达ng/g级别,低于采用钽罩的检出限。

Determination of nine impurity elements in high-purity quartz by direct-current glow discharge mass spectrometry using germanium as secondary cathode

As common impurity elements in high-purity quartz, Li, Be, B and Na have important influence on the product performance. Therefore, it is necessary to establish the corresponding determination method. A method for the determination of nine impurity elements (including Li, Be, B, Na, Mg, Al, S, Ti and Cu) in high-purity quartz by direct-current glow discharge mass spectrometry (dc-GDMS) was developed using germanium mask as the secondary cathode in experiments. The thickness of germanium mask used was 0.25 mm, and there were four slits with size of 1 mm×8 mm. The spacing between two slits was 1 mm. The influence of glow discharge parameters on matrix signal intensity, signal stability and the signal ratio of matrix to germanium mask was investigated. The experiments showed that when the discharge parameter was 1.3 mA/1 350 V, the signal intensity of matrix (²⁸Si) could reach 1.3×10⁹ cps. The discharge was stable, and the signal ratio of matrix to germanium mask was 1∶40. The contents of Li, Be, B, Na, Mg, Al, S, Ti and Cu in high-purity quartz sample were determined according to the experimental method. The relative standard deviations (RSD, n=5) of results were all within 30%. The effects of germanium mask and tantalum mask on the testing result of high-purity quartz were also compared. The results showed that due to the high content of Cu in tantalum mask, the determination result of Cu had great difference, while the determination results of other elements were basically consistent. Meanwhile, the detection limits of impurity elements in high-purity quartz with germanium mask could reach the ng/g level, which were lower than those using tantalum mask.