Standardization of EDS on FEI XL40 ESEM
The EDS software (EDAX Phoenix circa 2000) is standardized for analysis of phases likely found in concrete, cement paste in particular. As of December, 2012, element intensities were based upon the following:
Silicates wafer #1:
Element Mineral ID
F APAT (col_01.std and col_02.std) P APAT (col_01.std and col_02.std) Ti ILM1 (col_01.std and col_02.std) Mn NVGR (col_01.std and col_02.std) Fe NVGR (col_01.std and col_02.std) Si WOLL (col_02.std) Ca WOLL (col_02.std)
Silicates wafer #3:
O QTZ (col_01.std and col_02.std) Si QTZ (col_01.std) Al ANOR (col_01.std and col_02.std) Ca ANOR (col_01.std) Mg NBDI (col_01.std and col_02.std)
Standards files are noted in parentheses with their associated element/mineral relationships as two different standard sets were compiled.
- Silicates wafer #1 (ACMAL)
- Silicates wafer #3 (ACMAL)
- Polished willemite standard on pin stub mount (M&M 717)
- Mineral standards analyses (M&M 717 in black binder)
- Load one of the standards wafers and the willemite standard into the ESEM chamber. The standards wafer has two index points - orient the wafer so the points are at 12 o'clock and four o'clock on the stage x-y coordinate plane. Make sure the back scatter detector is in place. Pump the instrument down and saturate the filament at 15kV accelerating voltage prior to collecting spectra.
- While the filament is saturating:
- The wafer is much higher than the willemite standard, so z must be considered carefully throughout this procedure. Focus on one of the standards on the wafer and set FWD to 10mm.
- Locate the mineral standards on the wafer and save their locations in the stage map.
- Locate the willemite standard while keeping the FWD at 10mm relative to the wafer (the WD will increase to about 20mm upon focusing on the willemite). Save this stage location.
- Review EDS analysis method covering how to collect spectra.
- Start the SEM Quant ZAF program on the EDAX workstation.
- Click Setup>Presets and set live time to 200 seconds.
- Verify that the rate meter is set to integrate under the Zn peak with a range of 8.54 to 8.74 keV.
- In the Quantify window, make sure pure standards is selected (EDAX SEC should not be shown).
- The fundamental decision to make is whether to modify an existing standard set (.std file) or start one from scratch. Starting from scratch eliminates the possibility of having inaccurate element intensities for less often analyzed for elements, so that is what is recommended. Assuming this:
- Click the Quantify button (Fe/Cr) to open the Quantify window. Click the Factors button and set all element intensities equal to 1.00. Click OK when done.
- Create a folder with a logical name and save a new standards set (.std file) which will presently contain values of 1.00 for all elements.
Collect Spectra from Mineral Standards
The following steps will be performed on all of the necessary mineral standards:
- Select the willemite stage location and once over the willemite, set FWD to 10mm.
- Switch to spot scan mode.
- Collect a spectrum and make note of the integrated counts under the Zn peak in the rate meter window. Write down the number with its associated mineral ID.
- Select the willemite stage location which will move the stage away from the willemite standard and so avoid an expensive collision of the BSE detector with the standards wafer.
- Switch to full frame scan mode.
- Select the stage location of the mineral standard to collect a spectrum of. Set FWD to 10mm once the standard is in in the frame.
- Switch to spot scan mode.
- Clear the spectrum and collect a spectrum of the mineral standard.
- Once collection has started, click Edit>Edit spc file parameters and enter the BCF (integrated Zn counts/1000) and click save.
- Upon completion of collection, verify that the BCF is correct (Edit>Edit spc file parameters) and then save the spectrum using ID of the mineral standard for the file name.