熔融制样-X射线荧光光谱法测定稀土铝中间合金中稀土元素

稀土铝中间合金中稀土含量(质量分数,下同)一般约在0.5%~20%之间,文献中鲜见稀土铝中间合金标样和测定稀土含量大于10%的方法。实验通过选择钐的Lβ1线,镧、铈的Lα线,钇的Kα线,采用纯物质法配制标准溶液解决无标样问题,采用特散比法校正基体效应,对熔片条件以及仪器参数进行优化,建立了一套熔融制样-X射线荧光光谱法(XRF)测定稀土铝中间合金中镧、铈、钐、钇的方法。实验表明,称样0.2g,用5mL盐酸(1+1)熔样,四硼酸锂-偏硼酸锂混合熔剂熔融,稀释比选择1∶30,以4mL溴化铵溶液为脱模剂,控制熔样温度为1050℃,熔样时间为15min,熔样效果较好。实验方法应用于镧铝、铈铝、镧铈铝、钐铝、钇铝5类稀土铝中间合金中稀土元素的测定,测定结果与电感耦合等离子体原子发射光谱法(ICP-AES)结果基本一致,相对标准偏差(RSD)均在2%以下。方法可用于测定镧铝、铈铝、镧铈铝、钐铝、钇铝5类稀土铝中间合金中含量范围为0.5%~20%的镧、铈、钐、钇。

Determination of rare earth elements in rare earth-aluminum intermediate alloy by X-ray fluorescence spectrometry with fusion sample preparation

The content of rare earth elements in rare earth-aluminum intermediate alloy was usually 0.5%-20% (mass fraction, similarly hereinafter). The certified reference materials of rare earth-aluminum intermediate alloy as well as the determination method of rare earths with content higher than 10% was rarely reported in the literature. Lβ1 line of Sm, Lα line of La and Ce, Kα line of Y were selected as the analytical lines. The standard solutions were prepared with pure substances to solve the problem of no certified reference materials. The matrix effect was corrected by the characteristic/scattering ratio method. The fusion conditions and instrumental parameters were optimized. Thus, a determination method of rare earth elements in rare earth-aluminum intermediate alloy was established by X-ray fluorescence spectrometry (XRF) with fusion sample preparation. The results showed that the optimal sample fusion conditions were as follows: 0.2g of sample was melted with 5mL of hydrochloric acid (1+1); the mixture of lithium tetraborate and lithium metaborate was used as flux; the dilution ratio was 1∶30; 4mL of ammonium bromide solution was used as release agent; the sample fusion temperature was 1050℃ and fusion time was 15min. The contents of rare earth elements in five types of rare earth-aluminum intermediate alloys (lanthanum-aluminum, cerium-aluminum, lanthanum-cerium-aluminum, samarium-aluminum and yttrium-aluminum) were determined according to the experimental method. The results were consistent with the results obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the relative standard deviations (RSDs) of determination results were all less than 2%. The proposed method was applicable for the determination of lanthanum, cerium, samarium and yttrium (0.5%-20%) in five types of rare earth-aluminum intermediate alloys including lanthanum-aluminum, cerium-aluminum, lanthanum-cerium-aluminum, samarium-aluminum and yttrium-aluminum.