v.378PXRD DIFFRAC.TOPAS:

Quick Start Guide

V378P
V372| December 2017

Introduction

This guide is a quick introduction to the DIFFRAC.TOPAS software and how to use the program for profile fitting and Reitveld Refinements. For detailed information and an in-depth guide refer to DIFFRAC.TOPAS User Guide & Technical Reference available in hard copy in the XRD lab or online in Cumulus.
DIFFRAC.TOPAS is not a phase identification software. If you do not know the minerals present, first identify the phases using DIFFRAC.EVA and then use DIFFRAC.TOPAS to quantify those minerals.

Part 1: Opening a Diffractogram in DIFFRAC.TOPAS

Select the DIFFRAC.TOPAS icon on the desktop to open the software (Figure 1).

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In DIFFRAC.TOPAS a scan is referred to as a 'Range'. Multiple scans can be loaded and refined simultaneously.

Part 2: Identify Peaks

Peaks can be defined either automatically or manually inserted.

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3. With the mouse click on the center of each peak you want to identify directly in the scan window. The peak details window can be pulled up again to change the peak values.

Part 3: Set Refinement Parameters

Refinement parameters are set in the 'Parameter Window' and changed in the data grid. In the Parameter Window there are two parameter definitons: Global and Range. Global parameters apply to all scans in the parameter window. Range parameters will only apply to that specific scan.
To select a parameter, check the box in the 'Use' column in the parameter row (Figure 9). A parameter can then either be fixed or refined. Switch between 'fix' and 'refine' under the 'Code' column. Click inside the box next to your parameter. Select the drop down menu and choose between 'fix' or 'refine'. Note that a fixed parameter remains black and a refined parameter turns red. A fixed parameter can also be denoted with a '!' and a refined parameter with an '@'

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1. Right click on 'Instrument' and select 'Load Instrument Details'.
2. Navigate to Local Disk C > TOPAS 4-2 > Instrument details > D4EndeavourParameters.par
3. Select the file and click 'open'

Part 4: Run Refinement

When the parameters are set run the refinement.

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4. If the calculated line looks good select 'Yes' in the window to accept the refinement. If the calculated line does not look good select 'No' to reject the refinement and then go back to the parameter window and tweak the parameters. When a refinement is rejected the calculated curve will remain there until another refinement is run.

Part 5: Find Area Under Curve

1. In the parameter window go to your scan tree and select 'Peaks Phase' (Figure 13).

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3. These values can be copied and pasted into a personal spreadsheet.

Part 6: Weight Percent Analysis

A structure file contains crystallite size and indice values for minerals. Add structure files of each mineral present for TOPAS to calculate the weight percentage and/or the crystallite size. If evaluating multiple scans and using the same minerals to quantify each this can be done in 'Global' tree. If doing one scan or using different minerals for each scan, add structures scan by scan.

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1. Go to the parameter window and look at all the scans loaded in.
2. The colored box next to the scan indicates that a scan is active. Clicking on the box alternates it between 'active' and 'inactive'. In Figure 20 there are two active scans, quartz is blue and Illite is black. In Figure 21 the white box next to Illite illustrates that this scan is now inactive.
   
   

   Figure 20. Two Active Scans

   
   
   

   Figure 21. One Active Scan and one inactive scan

3. One scan can be run at a time so click on the colored boxes next to all but one scan. After this there should only be one scan seen on the graph.
4. Go to the refinement window and select 'Play'.
5. The message will appear stating the refinement converged and asking to accept or deny the refinement. Check the data before selecting an answer.
6. In the upper right corner, the weight percent of each mineral appears. Check the areas by following instructions listed in Part 5.

Part 7: Save and Export Image

Save a File

1. Select 'File' on the Menu Bar and go to 'Save project As…' (Figure 22)
   
   

   Figure 22. Save Project Pathway

   
   2.  Navigate to a place on the desktop on server and save the file.

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