布鲁克BrukerX射线荧光光谱分析备样技术.ppt

Folie,.,*,2001,Bruker,AXS All Rights Reserved,Arial 28 pt,Arial 16-24 pt,Arial 16-24 pt,Arial 16-24 pt,Arial 16-24 pt,Arial 16-24 pt,X,射线荧光光谱分析技术之二：制样方法,制样的,目的：,1、均匀,2、重复性好,3、颗粒效应小,4、矿物效应小,5、无限厚（薄膜法除外）,分析层的厚度：无限厚,X-ray tube,to soller slit,(collimator),analysed layer,(saturation depth),Sample,分析层的厚度无限厚,Sample,B KA1 (0,18 keV),Sn LA1(3,4 keV),Cr KA1(5,4 keV),Sn KA1(25,2 keV),tube,to soller slit,Is your sample homogeneous?,Analysed,layer,on the sample,surface,no excitation within the inner(upper)part of the sample,the lower parts(layers)of the sample can be excited(by short wavelengths)but,emmitted,radiation will be absorbed within the sample,fluorescence radiation to be measured comes from a layer near the sample(specimen)surface,分析层的厚度：无限厚,0,01,m,m=10 nm=100 A,atom radius:0,5 -3 A,tube,分析层的厚度：对于轻基体（如液体）,Light matrix,颗粒效应:,不均匀的颗粒样品,CaCO3,SiO2,压片样品,松散样品,颗粒效应:,不均匀的颗粒样品,分析层!,analysed layer,颗粒效应:,不均匀的颗粒样品,颗粒效应:,产生90%荧光强度的样品厚度,Thickness of the sample from which 90%of the measured intensity is derived,NBS 88b Dolomite,Pressed Pellet without binder,Especially for the lines of light elements,average grain size,layer thickness,(typically grain sizes vary between:20-200,m,m),X,射线荧光光谱可以分析的样品种类,固体，块状样品,金属块,矿石块,粉末状样品,矿石粉，如铁矿、煤炭,液体样品,油品,水样,块状样品的制样方法,对于金属样品,研磨,研磨+抛光（分析轻元素时需要）,需要考虑样品加工时带来的污染，如,SiO2、Al2O3,基体效应教严重，不过采用新的软件，可以对基体效应进行校正,块状样品的制样方法,对于矿样,考虑到样品的不均匀性，一般先制成粉末,也可以直接进行定性或半定量分析,粉末样品的制样方法,直接装入液体杯中测量，称为松散样品,压片制样,特点：简单、快速、节省,存在颗粒效应、矿物效应,熔融制样,制样精密度好,均匀性好,可以人工配制标样,消除了颗粒效应、矿物效应,缺点：制样麻烦、成本高、影响检出限,松散样品,Na to U,absorption in foil,He flushing required?,for qualitative and,semiquantitative,analysis,for quantitative analysis in special cases only,（,一般是压不成片的时候）,压片制样,press,as pure pellet,on a support of boric acid,in steel rings,in,aluminium,cups,add binder if necessary,wax(C and H),boric acid(BH and O),压片制样的精密度,熔融制样,熔融设备,马弗炉,燃气炉,inductively heated,熔剂,lithiumtetraborate,Li,2,B,4,O,7,lithiummetaborate,LiBO,2,mixtures of Li,2,B,4,O,7,and LiBO,2,白金坩埚(,crucibles and moulds),Analysis of Raw Meal Samples,Pressed pellets,versus,fused beads,Samples,six certified reference materials(Holderbank),Two different preparation methods,fused beads,0.9 g of material,8.1 g of flux,pressed pellets with 20%of wax,Analysis of Raw Meal Samples,Pressed pellets,versus,fused beads,压片制样和熔融制样的分析结果的比较,压片制样和熔融制样的分析结果的比较,The comparison of the two different preparation methods clearly shows:,sensitivities,and,LLDsare better for pressed pellets,the,accuracy,is much better for fused beads,up to a factor of 10 for SiO,2,液体样品,水,油,溶液,泥浆,.,尽量不要分析对仪器有腐蚀或污染的样品，如酸溶液,液体样品：,用液体杯直接分析,不同的样品要选择合适的膜,光路为氦气光路，千万不要抽真空,液体样品可以分析的元素范围,:,Na-U,WD-XRF,Mg in Oil:0-900,ppm,WD-XRF,Mg in Oil:0-900,ppm,油品样品中各元素的检出限,液体样品：滤纸片法,small quantities of sample(several 100l),dropped on a filter paper with an hydro-phobic ring to guarantee a constant area over which the sample is spread,unloaded filters necessary for blank measurement,熔融制样方法：,常用熔剂,Li2B4O7（,熔点,：920,o,C,）,LiBO2,（,熔点,：850,o,C,）,Li2B4O7+LiBO2：,混合熔剂,如12：22,常用的熔融比：1：5，1：10，1：20,脱模剂（改变熔液的浸润特性，以方便脱模）,LiBr,KI,NH4I,KBr,氧化剂,NaNO3,NH4NO3,LiNO3,熔融制样方法：典型的熔融方法,铁矿制样熔融制样方法,5,g Li2B4O7+0.5,样品+1,mL LiBr,(30mg/,mL,)+1mL LiNO3(220mg/,mL,),电炉上烘干10,min,1100,C,熔融10,min,冷却成型,