ICDD PDF-4+ 2012 Instructions

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Phase analysis in action: Examples Example 1: Titanium dioxide It can often be a good idea to perform XRD on your reagents before you begin your sample preparation work; any problems can be spotted before they ruin hours of good work! Here, I was checking that my reagent, TiO2, was what it said on the bottle -‐ and in the crucible after it had been dried at 900 °C! There are two known polymorphs of TiO2: anatase and rutile. The data were collected on the STOE Imaging Plate detector, with a total scan time of around 38 minutes. Phase analysis was then conducted using the SIeve+ software. I clicked on the periodic table tab and selected both Ti and O, omitting all other elements. This simple search returns 462 cards including many such as TiO, Ti2O3 etc. Scanning through the list for mineral names highlighted quite a few anatase and rutile phases – in this first plot, from WinX POW , I compare my experimental data (in green) with <strong>PDF</strong> card number [21-‐1272], a *-‐quality entry, for anatase:
It can immediately be seen that the sample does not contain anatase – none of the most intense Bragg reflections for anatase, e.g. the (101) peak at 25.281 °2θ, are observed in the experimental dataset. If we compare instead with rutile (graphics from WinX POW ): All of the Bragg reflections, including all those of low intensity, for rutile are observed in our dataset; there are no additional reflections. We can be confident that this sample is the rutile phase of TiO2. What was apparent, however, was a small linear peak shift across the diffraction pattern – the experimental reflections were always at a slightly higher angle than those from the <strong>PDF</strong> card. This is likely caused by a small misalignment of the diffractometer. Had the data been collected on a Bragg-‐Brentano geometry instrument, this peak shift would more likely have arisen from a specimen height displacement error. Remember: all experiments have errors! Finally, had the peak shift been non-‐linear, i.e. a small shift at low angles and larger at higher angles, it most likely would have been a sample effect – some change in the chemistry of the sample causing a change in the unit cell dimensions. Of course, SIeve+ can automate this process to some degree. In the Search window, I set up search filter: ‘Yes’ for Ti,O and ‘No’ to all other elements. I also selected to omit deleted
Page 1 and 2: ICDD PDF-‐4+ and SIeve+ Softwar
Page 3 and 4: Setting up your data The first thin
Page 5 and 6: Searching the Database The database
Page 7 and 8: Starting SIeve+ and loading your da
Page 9 and 10: your sample. The software will then
Page 11: Common problems ‘I have found a c
Page 15 and 16: Example 2: Nb,Cu-‐doped Titaniu
Page 17 and 18: slightly different composition (whi
Page 19 and 20: By also accepting the Si card, SIev
Page 21 and 22: Next, I select the elements of inte
Page 23 and 24: Further Reading The ICDD software h
Page 25 and 26: Appendix 2: Quality Marks The edito

ICDD PDF-4+ 2012 Instructions

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