Table of Contents
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This guide is a quick introduction to the DIFFRAC.EVA software (version 5.1) and how to use the program to solve crystalline phase identification. For detailed information and an in-depth guide refer to DIFFRAC.EVALUATION User Guide & Tutorial available in hard copy in the X-Ray Lab or online in Cumulus at /wiki/spaces/LN/pages/7338166219.
For former version of DIFFRAC.EVA software, refer to hard copy available in the X-Ray Lab.
Opening a Diffractogram in DIFFRAC.EVA
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Figure 2. View of a Diffractogram in EVA
Removing the Background
The first step in preparing a scan for Search/Match phase identification is to subtract the background (Figure 3). There are two methods for removing the background:
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In Data Command Panel, select Tools > Background to open the Background dialog box (Figure 3). Default view is 'Original + Background'. If needed, use the slider on the left to adjust the curvature on background humps. When satisfied, in the drop-down box, select Background subtracted option. Close the text box 
. The background is removed, and the diffractogram is changed to baseline.
Search/Match
The Search/Match (scan) tool in the Data Command Panel attempts to match XRD scans with patterns found in the ICDD (International Centre for Diffraction Data) PDF database. The Search/Match process tries to identify an unknown scan based on pattern recognition techniques. EVA can also find a reference pattern by its name or ICDD number.
Note: It is at the user's discretion to identify and choose the correct pattern matches.
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Select the desired search parameters (see suggestions below and Figures 6, 7 and 8). Once the desired parameters are selected, click Rebuild to rebuild the database for your selections. After the database is rebuilt, click back onto Candidate List and click Match.
Figure 4. A. Search/Match, B. Auto Views Panel, C. Search/Match dialog box
In the Criterion field of the Options Tab (Figure 5), begin the search with 2: Neutral.
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In the Databases Tab, select the DB Filter. Click on the "three dots" button 
(Figure 6A). The Database Filter window opens (Figure 6). The default name is 'Database Filter #1', and the database used is "PDF-2 2001". The Search/Match can be enhanced using database filters such as the following (Figure 6):
–Quality Marks: Degrees of pattern quality assigned by ICDD. Recommended: *, Calculated, Indexed (a).
–Status: Recommended: Primary (b).
–Colors: Select the color of the mineral to be searched.
–Sources: Database section: select both ICDD Database (experimental) and ICSD Database (ICSD-FIZ) (c).
–Subfiles: Select the group of patterns to be searched, for example, inorganics, zeolites, minerals, etc. (d).
–Element # in Formula: Choose the minimum/maximum number of elements considered in the formula (default values are min=1 and max=24).
–Density: Enter a minimum/maximum density for the mineral being searched (default values are min=1 and max=80).
Figure 6. Database Filter.
Chemical Filter
In the Databases Tab, select Chemical. Click on the "three dots" button . The Chemical Filter window opens (Figure 7). The default name is 'Chemical Filter #1'. A chemical filter can be set for any element in the periodic table (Figure 7).
–Green = M = Mandatory. All elements shall match.
–Red = D = Discarded. Exclude from match.
–Blue = A = At least one element shall match (must be present in the search result).
–Gray = N = Neutral. Element may match.
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Figure 7. Chemical Filter.
Candidate List Tab
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Once the desired parameters are selected, click Rebuild to rebuild the database for your selections (Figure 6B). After the database is rebuilt, click back onto Match Lists (Figure 8). In the drop-down menu, select the list of clay minerals and common minerals and click OK (Figure 8A). Then, click Match (Figure 8B).
Close the window.
Figure 8. Match Lists
In the Auto Views panel, the list of candidates appears (Figure 9). Expand the table to see important information on the candidate (Figure
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9), including
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:
–Index # 
: Rank number of the given pattern during the Search run
–Match: Number of reference pattern lines matching the unknown. The Match Column gives: on the left (green bar) the number of reference pattern lines matching the unknown in the displayed range, on the right (orange bar) the number of reference pattern lines not matching the unknown.
–FOM: Figure of Merit –
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the higher this number, the better the match. Patterns are sorted by decreasing FOM. The FOM is represented by a blue bar proportional to its value.
Check the tick box (green square in Figure 8) to add selected peaks. To delete selected peaks, right-click on the selection and choose 'Delete'.
Figure 8. Search List Tab in the Auto Views Panel
Residual Scan – Searching the minor phases
Minor phases are often sometimes difficult to identify because the patterns of the major peaks are higher on have a better position in the list. Using the Residue tool will exclude the already matched patterns and increase the weight of the minor phases.
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1.
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In Search/Match (scan) screen, choose the Selected Candidates tab.
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2.
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Select the pattern you wish to exclude in your next search.
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3.
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Select the Residue tool.
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Adjust the width of the zone to exclude around the pattern peaks.
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Click Apply.
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Click back onto Candidate List Tab and click Match.
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The candidates for the residual scan are listed in Candidate List
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Select the Scissors tool from the View Window toolbar.
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2.
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Cut the peaks that you wish to exclude from the Search/Match.
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3.
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Under Search/Match (scan) box,in the Candidate List tab, select Match.
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The program will search the peaks left uncut.
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5.
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Click 
(Residual Scan) or right-click anywhere on the Graphical 1D View and then choose Residual Scan > Residue (all scans) (Figure 9). Select the area you want to exclude. The area will be displayed in red. To restore the excluded part, click the Undo arrow 
or right-click and choose Residual Scan > Restore (all scans).
Check the tick box (green square in Figure 9) to add selected peaks. To delete selected peaks, right-click on the selection and choose 'Delete'.
Figure 9. Residual Scan
Peak Search
Peak Search detects peaks automatically and is useful for phases not identified with Search/Match or to export the pattern to another program.
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1. | Select the scan in the data tree. |
2. | Click Peak Search in the Tool List of the Data Command Panel. The Peak Search dialog box is displayed. |
3. | Move the slider to select the peaks you desire (Figure 9). |
4. | Once you are satisfied, click Make Dif to create a DIF pattern. The pattern list is created in the Data Tree and can be Search/Matched. |
5. | To select specific peaks click Append to List and a peak list is created in the Data Tree (Figure 10). |
6. | Highlight the peaks you want and click Search/Match (peak list) under Tool or Make DIF Pattern (which you can export to another program). |
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Figure 10. Peak Search with Append List.
Printing in EVA
You can print any of the views in EVA.
Print Preview allows you to enter header and footers onto your print out, in addition to editing axis and labels. You can also Export the print preview as an image *.PNG file.
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