悬浮液进样-液体阴极辉光放电原子发射光谱法测定高纯氮化硅粉体中微量杂质元素

针对高纯氮化硅粉体中的9种微量杂质元素(Al、Ca、Co、Fe、K、Mg、Mn、Na、Ni),建立了悬浮液进样-液体阴极辉光放电原子发射光谱定量分析方法.考察了制备稳定悬浮液对样品颗粒度的要求,并通过六通阀将悬浮液引入液体阴极辉光放电原子发射光谱装置检测.本方法采用水溶液标准进行定量分析,无需对悬浮液的pH值进行精确调节,能够保持液体阴极辉光等离子体的稳定性.研究了仪器装置的操作电压、载液流速、光电倍增管积分时间等因素对检出限的影响.优化后得到的最佳实验条件为操作电压1080 V,载液流速1.2 mL/min,光电倍增管积分时间800 ms.利用六通阀进样系统对原有的液体阴极辉光放电原子发射光谱装置进行改进,从而实现悬浮液直接进样检测.用此装置对氮化硅实际样品进行检测,得到各种元素的检出限在0.2~53 mg/kg之间,RSD在1.1%~5.0%之间.通过对氮化硅标准参考物质ERM-ED101进行分析,其测定结果与高温高压消解-电感耦合等离子体发射光谱法一致,并与标准参考值吻合,表明此方法可用于氮化硅粉体的悬浮液直接进样检测,结果准确可靠,灵敏度高,具备应用价值.

Determination of Trace Metals in High-purity Silicon Nitride Powderby Solution-cathode Glow Discharge-atomic EmissionSpectrometer Using Slurry Sampling

Trace impurities of Al, Ca, Co, Fe, K, Mg, Mn, Na, Ni in silicon nitride powder were determined by slurry introduction into a solution-cathode glow discharge-atomic emission spectrometer (SCGD-AES).The effect of particle size on the stability of suspension was investigated.A 6-port valve was selected to link sampling system and SCGD-AES, by which the suspension could be introduced into the SCGD-AES to get instantaneous spectrum signal.The calibration curves for quantitative analysis could be established using aqueous standards and the pH of suspension was not required to be adjusted accurately.The applied voltage, solution flow rate, and integral time of PMT were set to 1080 V, 1.2 mL/min and 800 ms, respectively.In this work, slurry sampling was combined with SCGD-AES by a 6 port 2-pos valve.Powder Si3N4 was tested by this way and the limits of detection for all nine elements were 0.2-53.0 mg/kg.The RSDs were 1.1%-5.0%.The detection result of trace impurities in standard reference material ERM-ED101 agreed with that obtained from inductively coupled plasma atomic emission spectrometry.This method was proved to be accurate, reliable and valuable.