Sample Analysis using Mapping Thermo Scientific ARL PERFORM’X 4200 Advanced WDXRF Spectrometer

InstrumentThe ARL PERFORM’Xspectrometer used for these testswas a 4200 Watt system. Thissystem is configured as standardwith 6 primary beam filters, 4collimators, up to nine crystals, twodetectors, and our 5 GN Rh X-raytube for best performance fromultra light to heaviest elements.

The ARL PERFORM’X analyzerfeatures mapping and small spotanalysis allowing for 1.5 mm and0.5 mm areas.

Mapping of geological samplesThe ARL PERFORM’X mapping of this geological sample illustratesthe ability to define and locate grain boundaries and crystallinestructures that are not visible to thenaked eye.

The formation of pseudotachyliteis usually studied without referenceto its chemistry, but in this examplewe can see a wealth of chemicalinformation that bears upon thegenesis of the material. Al, Si, K, Caand Fe show large gradients whileNa, Mg, Ti and Sr are more evenlydistributed.

Application Note: AN41652

Key Words

• ARL PERFORM’X

• Mapping

• X-ray fluorescence

• XRF

Figure 1: Pseudotachylite sample withanalyzed area

Figure 2: Distribution of nine elements in the sample

IntroductionWavelength dispersive XRFspectrometers are typically used forquantitative elemental analysis ofmany material types ranging frompetrochemical, geochemical, metals,glass and ceramics, mining andcement. These samples are normallypresented to the XRF instrument asuniform and homogenouslyprepared samples.

With the introduction of theThermo Scientific ARL PERFORM’Xspectrometer, a new dimension ofsample analysis is now possiblewith sample surface mapping. The mapping capability enablesheterogeneity, contamination,gradient, segregation and inclusiondetermination and analysis.

The ARL PERFORM’X mappingoption can construct detailedcomposite maps of elementaldistribution within a sample. Thecartography control and overlay hasa fine resolution of 0.1 mm stepsproviding superior analysis forprocess improvement and problemsolving applications.

This ability bridges the gapbetween traditional bulk analysisand standard micro-analysis usingmicroscopic techniques such asSEM.

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AN41652_E 03/11C

Another example is shown inFigures 3 and 4 with a feldsparsample having a clearinhomogeneous structure. The ARL PERFORM’X identifiesthe element constituents in theselected section of the sample.

The interesting aspect of thisanalysis is in the differences ofchemistry of the two feldspars, andhow the plagioclase comes tomantle the earlier alkali feldspar.The chemistry gives a lot of basicinformation regarding this process.

Mapping of metallic samplesMapping can be used for easyidentification and quantification ofcontamination or metallic inclusionsas shown in Figures 5 to 8.

Standard-less analysis for mappingThe most useful development ofXRF analytical programs has beenthe availability of “standard-less”

Thermo Fisher Scientific (Ecublens) SARL,Switzerland is ISO certified.

Figure 3: Heterogeneous feldspar sampleseen in the 30mm aperture sample holder Figure 4: Distribution of eight elements in the sample

packages. These packages allow forquantitative data to be obtained forcompletely unknown samples.

As in many real life situations,obtaining any or enough standardsto create a calibration is not alwayspossible. This is certainly the casewhen analyzing defects or unknowncontamination. In such situations,we can offer the most comprehensivestandard-less software on the market:Thermo Scientific UniQuant package.

It is a factory calibration basedon 64 pure element standards thatallows for concentrationdetermination of unknown samplesin any matrix by using complexmathematical algorithms for up to79 elements. These algorithmscorrect for matrix effects as well as

inter-elemental effects to provide aprecise quantitative result.

ConclusionThe elemental mapping capability is a very interesting tool for allapplications dealing withheterogeneity or concentrationgradients in samples as well as whenimpurities or inclusions are found ingiven specimens. It is seen thatanalysis using mapping can easilybe performed with the ARLPERFORM’X sequential XRFspectrometer.

Operation is made easy throughthe state-of-the-art Thermo ScientificOXSAS software which is able tooperate with the latest MicrosoftWindows® 7 packages.

Figure 5: Selected areafor mapping in green

Figure 6: Distribution of Cr Figure 7: Distribution of Cu Figure 8: Distribution of Fe

Acknowledgement: Our thanks to Richard Conrey of Washington State University for submitting the geological mappings and useful discussions.

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