SIMPLIFIED MATERIALS ANALYSIS VIA XRF. Ravi Yellepeddi and Didier Bonvin Thermo Fisher Scientific (Ecublens) SARL, Ecublens/Switzerland

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1 SIMPLIFIED MATERIALS ANALYSIS VIA XRF Ravi Yellepeddi and Didier Bonvin Thermo Fisher Scientific (Ecublens) SARL, Ecublens/Switzerland

2 SIMPLIFIED MATERIALS ANALYSIS VIA XRF Ravi Yellepeddi and Didier Bonvin Thermo Fisher Scientific (Ecublens) SARL, En Vallaire Ouest C, CH Ecublens, Switzerland Introduction: Among the various analytical techniques available today for the chemical characterization of materials, X-ray fluorescence (XRF) stands out as one of the most advantageous and reliable methods. In comparison with most other analytical methods, XRF offers a non-destructive, accurate and highly reproducible analysis with little or no sample preparation in a wide dynamic range (sub ppm to 100%). Wavelength dispersive XRF is one of the well established techniques for the analysis of materials in the cement and mining, ferrous and non-ferrous metals, ceramics, refractories and glass, inorganic chemicals and other industries. This technique is becoming a reference method in the area of petrochemicals (oils, polymers, additives etc.) and is increasingly applied in the areas traditionally reserved for ICP or AA methods. Recent developments in the XRF instrumentation have indeed helped to enhance the sensitivities across the periodic table and expand the capacity to handle a larger variety of samples (solids in the form of metals or pressed pellets or fusion beads, loose powders, liquids, granules, small and irregular samples, slurries, filters and thin films etc.). The most striking development in the recent past has been the availability of the so called standard-less or semi-quantitative analysis programs. XRF like many other analytical techniques remained a comparative method for a long time and a set of certified reference materials was required for quantitative analysis. Thanks to these standard-less analysis packages linked to fast sequential goniometers, WDXRF has become the most powerful tool in any central analytical laboratory. Instrumentation: The most appropriate type of XRF instrument for the global materials analysis is the sequential system with a universal goniometer. Two types of sequential instruments depending on the type of samples, the analysis turn-around time and their frequency can be proposed. Figures 1 and 2 show the cross section and geometry of these two instruments: ARL ADVANT X with the X-ray tube below the sample for solids, liquids and loose powders and ARL 9900 with the tube above the sample for rigid solids (pressed pellets, metals, glasses or fused beads). Figure 4 shows the variety of samples that are commonly analyzed. Apart from the difference in the geometrical arrangement, the XRF goniometer (Figure 3) can be identical in both instruments in terms of its speed, flexibility and versatility. Furthermore, the ARL 9900 can be fitted with two goniometers which analyze the sample simultaneously thus cutting the analysis time by half or by a series of fixed channels allowing simultaneous analysis of selected elements. For enhanced performance and sensitivity, both instruments can be equipped with mid or high power generators and X-ray tubes (1200W to 4200W) depending on the speed of analysis and the limits of detection required. The 1200W and 2500W versions do not require external water chiller. Both the ARL ADVANT X and ARL 9900 can be fitted with large capacity X-Y autosamplers (Figure 4) in order to accommodate series of samples that are analyzedillustrated in Fig. 4 in batch mode using the unattended mode of operation. The ARL 9900 Series instrument is unique as it can accommodate in addition an Integrated X-ray Diffraction system (either Full or Compact) that will allow phase analysis of crystalline materials.

3 SAMPLE X-RAY TUBE X-RAY TUBE GONIOMETER GONIOMETER 1 SAMPLE GONIOMETER 2 Fig. 1: Conventional sequential WDXRF Fig. 2: Unique dual sequential XRF Fig. 3: Types of samples/materials analyzed by XRF Fig. 4: Automatic batch handling of solids, liquids, powders, granules, fusion beads, etc.

4 Analytical tools: The heart of sequential WDXRF instruments is the goniometer whose details and operating principle are shown in Figure 5a and 5b. Analytical expertise necessary to perform instrument optimization, qualitative scans, creation of analytical programs etc. is built into the proprietary operation software. Based on the table of Mendeleev, the integrated Analytical Assistant function (Fig. 6) allows users with little or no knowledge of XRF to build analytical programs easily without risk of choosing inappropriate parameters. As discussed above, both the ARL ADVANT X and ARL 9900 can be used for qualitative and quantitative analysis provided suitable standards are available. In these cases, limits of detection that can be achieved for various applications are shown in the following section. Detector grating 2 θ drive X-ray tube Fixed detector-reader head Detector Secondary collimator Crystal Crystal grating 1 θ drive Sample Fixed crystal-reader head Primary collimator Fig. 5a: Universal goniometer Fig. 5b: Goniometer principle of operation Fig. 6: OXSAS software: Analytical Assistant Fig. 7: Goniometer scan graphics with peak identification However, when no specific standards are available to determine calibration curves, no calibrations are possible and when no appropriate sample preparation is possible, the semi-quantitative analysis programs become extremely useful. Two types of standard-less analysis packages can be proposed in conjunction with the goniometer: QuantAS and UniQuant QuantAS is based on global scans (Figure 7) followed by spectral processing while UniQuant performs peak and background measurements followed by intensity processing.

5 Typical results: Analysis of various materials In the following sections, analysis of various types of samples is illustrated using both quantitative and semi-quantitative programs. Typical limits of detection have been presented in some pure metals, oils, polymers, aqueous solutions, oxide materials. These values were obtained using a series of standards. Some examples of the semi-quantitative analysis have also been presented to illustrate the performance of such programs in the cases of difficult samples. A. QUANTATITATIVE ANALYSIS A.1. Applications in geology, mining, cement, glass and oxide industries Analysis of soils & stream sediments Analysis of oxide materials Analysis of glass Element Element Oxide/ Element As 1.8 CaO 9 Na 2 O N.R. Cd 2.5 SiO 2 10 MgO 10.3 Co 1.0 Fe 2 O 3 9 Al 2 O Cr 0.7 MgO 58 SiO 2 N.R.* Cu 0.6 Al 2 O 3 25 SO Hg 1.3 K 2 O 8 K 2 O 1.3 Mo 0.3 MnO 6 CaO N.R. Ni 0.6 Cr 2 O 3 5 TiO Pb 1.1 TiO 2 5 Fe 2 O Sn 3.2 P 2 O 5 13 As 2 O V 0.3 SO 3 13 SrO 1.0 Zn 0.3 Na 2 O 113 Co 2 O Se 1.0 *N.R. = Not Relevant Cl 3.0

6 A.2. Applications in petrochemicals and liquids Analysis of oils Analysis of traces in polymers Analysis of traces in aqueous solutions Element Element Element 4200W 2500W Mg 2.2 Mg 0.86 As 1.1 Al 0.67 Al 0.23 Ba 0.9 Si 0.38 Cr 0.11 Cd 1.1 S 0.25 P 0.16 Co 0.3 Ca 0.1 Cl 0.30 Cr 0.3 Cr 0.2 Ca 0.14 Cu 0.2 Mn 0.2 Ti 0.10 Hg 0.6 Fe 0.2 Fe 0.07 Ni 0.2 Cu 0.2 Pb 0.4 Zn 0.2 Zn 0.2 Sn 0.4 Pb 0.14 Analysis of Ni and V in gas oil Element [ppb] V 76 Ni 28

7 A.3. Applications in metals industry Ferrous base Analysis of traces in aluminum Analysis of traces in pure copper Analysis of traces in pure silver Analysis of traces in platinum El. 2500W El. 4200W El. 4200W El. El. Al 2.6 Si 2.1 Sn 4.7 Fe 3.1 Fe 4.0 Bi 4.2 Na 3.1 Cr 1.0 Ni 2.5 Ni 3.0 Ca 1.3 Ca 0.5 Zn 2.2 Cu 2.3 Cu 2.6 C 89 Ti 0.6 Pb 2.8 Zn 2.4 Rh 15.0 Ce 4 V 0.6 Fe 0.9 Ru 6.5 Pd 12.9 Cr 2 Cr 0.7 Ni 1.2 Rh 17.3 Ag 17.3 Cu 2.2 Mn 0.6 O Pd 10.6 Ir 10.6 Mg 19 Fe 0.8 S 0.5 Cd 16.6 Au 16.6 Mn 2.3 Ni 0.5 Bi 2.5 Sn 14.8 Pb 14.8 Mo 1.2 Cu 0.5 Co 0.6 Sb 15.3 Nb 1.3 Zn 0.4 Sb 5.7 Ir 2.7 Ni 1.8 Ga 0.3 As 6.7 Pt 2.2 P 1.1 Ag 1.7 Ag 5.2 Au 2.2 Pb 5.6 Cd 1.7 Se 1.2 Pb 4.4 S 1 Sn 1.9 Rh 4.6 Bi 2.2 Si 3.5 Pb 0.4 Cd 5.9 Sn 9.2 Mg 6.0 Mn 0.8 Ta 6.8 Co 0.6 Te 8.8 As 1.6 Ti 1.3 Hg 0.6 V 1 Bi 0.3 W 4.8 Zn 2.2 Zr 1.3

8 B. STANDARD-LESS ANALYSIS B.1. QuantAS Analysis of rare-earths in fusion bead form Analysis of sediments Element Concentrations Element Concentrations Given QuantAS Given QuantAS SiO % 30 % SiO2 76.3% 76.0% Dy2O % 5 % Al2O3 10.4% 13.4% Nd2O % 5 % Fe2O3 4.39% 4.32% Sm2O % 5 % K2O 3.28% 3.55% Ho2O % 5 % MgO 0.620% 0.748% Eu2O % 5 % CaO 0.470% 0.444% Tm2O % 5 % Na2O 0.460% 0.401% Pr6O % 5 % TiO % 0.355% CeO % 5 % MnO 0.321% 0.300% Lu2O % 5 % SO3 424 ppm 800 ppm La2O % 5 % PbO 685 ppm 700 ppm Yb2O % 5 % Rb2O 446 ppm 520 ppm Er2O % 5 % P2O5 584 ppm 510 ppm Gd2O % 5 % ZnO 464 ppm 480 ppm Tb4O % 5 % Cl 290 ppm 330 ppm SnO2 420 ppm 320 ppm Analysis of maraging steel BaO 321 ppm 280 ppm As2O3 248 ppm 210 ppm ZrO2 207 ppm 170 ppm WO3 159 ppm 130 ppm CuO 98 ppm 100 ppm Element Concentrations V2O5 84 ppm 61 ppm Given QuantAS Sb2O3 19 ppm 60 ppm Fe 31.2% 30.5% Y2O3 54 ppm 59 ppm Ni 21.8% 22.1% Bi2O3 56 ppm 57 ppm Cr 21.6% 21.9% Nb2O5 36 ppm 37 ppm Co 17.8% 17.8% SrO 34 ppm 34 ppm Mo 2.83% 2.86% NiO 18 ppm 23 ppm W 2.38% 2.39% Ga2O3 25 ppm 22 ppm Mn 0.910% 0.941% ThO2 27 ppm 3 ppm Ta 0.752% 0.790% Si 0.382% 0.414% Al 0.134% 0.240% La 265 ppm 280 ppm Ti 232 ppm 270 ppm V N.A.* 180 ppm Cl N.A. 170 ppm *NA = Not Available Ca N.A. 120 ppm K N.A. 110 ppm Cu 206 ppm 110 ppm Nb 110 ppm 59 ppm P 112 ppm 12 ppm

9 B.2. UniQuant 1) Applications in food industry Soy based baby food Animal food (pressed pellet) Element Concentrations Element Concentrations Uniquant % % cert. UniQuant % % cert. K K Ca Ca Cl Cl P P Na Na S Mg Mg Si N.A. Fe Zn Zn N.A.* Mn Si N.A. Fe Br N.A. Cu Nb N.A Pb N.A. Zr N.A. *N.A. = Not available Cu Mn ) Analysis of small and irregular samples Analysis of stainless steel drillings Analysis of filters Element Element UniQuant [μg] Cert. [μg] Mn 1.34 % 1.37 % 1.37 % V Si 0.36 % 0.30 % 0.37 % Cr Cr % % % Mn Ni % % % Fe Mo 1.91 % 1,47 % 1.80 % Ni Cu % 0.08 % Cu Ti % % % Zn Fe 66.4 % 67.3 % 66.4 % As Nb % Se Ag Cd Ba The drillings were analyzed under helium environment with a film support (6 micron PP) Pb

10 Conclusions : Wavelength dispersive XRF technique has been shown to be the most versatile and cost effective analytical method for materials characterisation. Two types of sequential instruments - one of them offering a unique dual goniometer system - which satisfy the most demanding analytical needs have been described. Both quantitative analysis based on specific calibrations and standard-less analysis for samples without suitable reference materials have been performed using these instruments. It is shown that analysis of oxide materials such as minerals, glass, soils and sediments, ceramics, cements, petrochemical products such as oils and polymers, ferrous and non-ferrous metals, food products, waste and incineration products etc. can easily be performed.

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