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Obnovit | RAW

Laboratory of X-ray Diffractometry and Spectrometry

Reports from XRF spectrometrs ARL 9400, Performix and Axios–standardless analysis

 Elements F-U in reports may be expressed either as elements or oxides (exceptionaly as another compounds) or as combination of elements and oxides. It is not possible in simple way from XRF analysis to judge in which chemical form are elements present in the sample (XRD can help). The value „Sum Conc's before normalisation“ may be used to help and  should be 100%, if the following ias fullfiled - proper amount of sample, correct choise of chemical form of present elements and no  unmeasurable elements ( H-N) in sample. The values „Sum Conc's before normalisation“ in range 98-102% are OK.

 The goal of sample preparation is to achieve „Sum Conc's before normalisation“ in range 98-102%

 „Sum Conc's before normalisation“ includes elements with + sign in case of spectrometrs ARL9400 and Performix and elements present in report for spectrometr Axios. Software presents elements with concentration higher than 2xStdErr, we consider more reliable if calculated concentration is higher than 3xStdErr. Operator may define the minimal reliable concentration respect to time of mesurement. It is about 30-50ppm, (resp. 0.003-0.005%) for standard measurement speed (15-20min/sample). Each element has got  different detection limit, light elements F-Si are more difficult to detect.

XRF - spectrometer ARL 9400

 Report for sample with elements if form of oxides – report in  oxides 

Report for sample with elements if form of elementss – report in elements .

Samples may include hydrates (unmeasurable H, O). This case may be solved by heating the sample and using method LOI or less laborious and often convenient including calculation of unmeasurable rest – H2O. This is the case of impurity determination in calcium sulphate dihydrate CaSO4.2H2O . Elements of interest Zn and Pb as elements, other elements as oxides.

If Ca is present as CaCO3 than report in form oxides  has got „Sum Conc's before normalisation“ smaller than 100% (e.g. 89%), which  demonstrates presence of unmeasurable part, in this case CO2. Report with stochiometrically calculated CO2  has got „Sum Conc's before normalisation“ in range 98-102% (100.9%).

If  Ca is present as CaCO3, CaSO4.2H2O, CaO i Ca(OH)2 than the most accurate result can be achieved by LOI (Lost On Ignition) method. We may weight such an amount of sample, that after heating we have suitable amount for XRF analysis. The simplest case is when 1g is OK, heating at proper temperature and long enough to get oxide. Than weight calcinated product and for weight 0.59g we get LOI =41. This value is inserted in program and we obtain concentration of elements as oxides in final report before heating.

Uniquant 4 will normalize all results to 100%, there is no chance to get results without normalisation.

It is possible to summarise results from more samples in Excel file – summarisation of  results. Only elements of interest are usually presented for clarity. 

XRF - spectrometer Performix

Report for sample with elements if form of oxides – report in  oxides . 

Report for sample with elements if form of elementss – report in elements .

Integrated  Uniquant 5 may produce results with or without normalization.

 

XRF - spectrometer Axios

Report for sample with elements if form of oxides – report in  oxides . 

Report for sample with elements if form of elementss – report in elements .

Peak intensities from 11 measured scans are used to calculate element concentration using spectrometr Axios and standardless software Omnian. The main advantage of  software Omnian respect Uniquant is possibility to check the presence of trace elements by searching the scan  and with eye judging if the peak of an element is or is not present. The disadvantage is the longer time of measurement and from the statistical point of view less precise measured intensities. The significant advantage is the possibility to compare scans of more samples together in one figure.     

EDXRF – portable spectrometer XL5

Determination of materiál grades – possibility  to compare element composition of sample with inbuilt library of alloys (e.g. determination of  material grade).

Layer thickness determination – layer thickness can be mesured in range 0.01-100 micrometrs and present in different units (micrometrs, g/cm2). Layer thickness Cu on Fe substrate.

Updated: 23.7.2018 10:04, Author: Jan Prchal


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Information provided by the Department of International Relations and the Department of R&D. Technical support by the Computing Centre.
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