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将多晶硅(硅粉)用氢氟酸和硝酸二次溶解,用高氯酸的二次冒烟去除氟离子对铝的干扰,用3 cm的比色皿解决铁低灵敏度带来的误差大的问题。使用分光光度法准确测定多晶硅中铁和铝的含量。研究了显色条件对显色反应的影响,确定最佳实验条件。结果表明,在pH3~5的乙酸-乙酸钠缓冲溶液中,铁与5 mL 0.25 g/L的1,10-二氮杂菲10 min后生成稳定的红色络合物,且在2~10μg/50 mL范围内服从比尔定律;在pH 5.5~6.1的六次亚甲基四胺缓冲溶液中,铝与5 mL 0.3 g/L的铬天青-S在15 min后形成稳定的紫红色络合物,且在4~16μg/50 mL范围内服从比尔定律。用分光光度法能准确测定纯度为99.99%多晶硅(硅粉)中铁和铝含量,并与ICP-AES法测试结果对比,相对误差在5%左右。
Polysilicon (silicon powder) with hydrofluoric acid and nitric acid secondary dissolution, with perchloric acid secondary smoke to remove fluoride ions on the interference of aluminum, with 3 cm cuvette to solve the low sensitivity of iron caused by the error problem. Accurate determination of iron and aluminum in polycrystalline silicon using spectrophotometry. The effect of color conditions on the color reaction was studied and the best experimental conditions were determined. The results showed that iron complexed with 5 mL of 0.25 g / L 1,10-phenanthroline in acetic acid-sodium acetate buffer solution at pH 3-5 for 10 min resulted in a stable red complex with a mass ratio of 2 ~ 10 μg / Beer’s law was obeyed in the range of 50 mL. Aluminum and 5 mL of 0.3 g / L chrome azure-S in distilled water of hexamethylenetetramine (pH 5.5 ~ 6.1) formed a stable purple complex after 15 min Beier’s law was obeyed in the range of 4 ~ 16μg / 50mL. The content of iron and aluminum in polycrystalline silicon (silicon powder) with purity of 99.99% can be accurately determined by spectrophotometry, and the relative error is about 5% compared with the ICP-AES method.