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Examples Exploiting Extra Features in DDView ICDD

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Examples Exploiting Extra Features in DDView ICDD Powered By Docstoc
					Data Mining with DDView+
 and the PDF-4 Databases

   FeO Non-stoichiometric Oxides




               Some slides of this tutorial have sequentially-layered
               information that is best viewed in ‘Slide Show’ mode
 This is one of three example-based tutorials for using the
 data mining capabilities of DDView+ with the PDF-4+
 database and it covers the following topic:
 • FeO Non-stoichiometric Oxides
    – sorting out temperature and stoichiometric effects
      on cell parameters

 Two other similar tutorials for data mining exist and
 cover the following topics:
• CIGS Photovoltaics
  – solid solution / cell parameter relationship
• Carbamazepine Polymorphs
  – a PDF-4/Organics application
  – investigating polymorphic forms of an active
    pharmaceutical ingredient (API)
       Stoichiometric Factors Affecting the
            Diffraction Pattern of FeO

• FeO is frequently non-stoichiometric with
  Fe-site vacancies.
• These defects have crystallographic effects
  and can cause shifts in the observed powder
  diffraction peaks.
• Summaries of this effect can be “mined”
  from the PDF-4+ database and displayed for
  further study.
        Ideal Crystal Structure of FeO*

                                                        Cubic System
                                                        Space Group: Fm-3m
                                                        NaCl type structure




*Structure taken from PDF entry 04-004-7638 calculated from the LPF database.
Data Mining for FeO Entries: Step 1
Use the Preferences Window to establish what will be displayed in the
Search Results table . . .
                              1. Click the ‘Preferences’ icon
                              2. Click the ‘Search’ tab in the
                                  ‘Preferences’ window
             Selecting Fields for the Results Table


                                                      Selected Fields:
                                                        Use these buttons
                                                        to move a selected
                                                        item up or down in
                                                        the listed order for
                                                        the results table.




Available Fields:
    Use these buttons to move selected items between the
    ‘Available Fields’ list of 60 items and the ‘Selected Fields’
    list of items that will be displayed in the results table.
Selecting Fields for Results Table (FeO)



                       Setting up the fields as shown
                       here will serve the purposes of
                       this example.
                Chemistry Criterion for Search: Fe and O only entered on
                ‘Periodic Table’ tab of ‘Search’ window
Once entered, the chemistry
criterion can be verified here.                 Finally click ‘Add’ to include
                                                this criterion for the search.




               Then click ‘Only’ . . .
                                              First click elements Fe and O . . .
Structure Criterion for Search: FCC Space Group #225 – ‘Fm-3m’
         entered on ‘Structures’ tab of ‘Search’ window




Perform search using
specified chemistry
and space group
criteria.
    Results of DDView+ Search for FeO




A total of 63 entries for Fe1-xO compounds
            Analysis of the Resulting Database Entries
Most fields in the results table can be graphically illustrated in
either X-Y plot or histogram form.
For the current application, we will use an X-Y plot to illustrate the
a-axis cell parameter as a function of atomic % Fe.
To do this, ‘Graph Fields…’ is first selected from the ‘Results’ drop
down menu of the ‘Results’ window.
                   Choose X-axis field
                   from drop down
                   menu: ‘Atomic %’




Choose element
for Atomic %
values from drop
down menu: ‘Fe’




                   Choose Y-axis field
                   from drop down
                   menu: ‘XtlCell-a’

                     Click ‘OK’ to
                     draw Graph
  FeO a-axis Cell Parameter vs. Atomic % Fe
                                                               Stoichiometric – 1:1

                                             High Temperature




                                                                 Ambient




• This graph shows little apparent correlation between atomic % Fe and a-axis.
• Note that entries reported as being stoichiometric (1:1) are in a vertical line at
  right (50 at% Fe). All others report less than stoichiometric amounts of Fe.
• Further examination of individual entries separates ambient and high
  temperature determinations of the a-axis.
• Individual entries from this chart may be examined by left-clicking on individual
  spots. The circled spot corresponds to the entry on the next slide.
PDF Card for FeO (01-073-2144)




      Fe.942O



 The ‘PDF’ tab of this window displays
 the actual formula and stoichiometry.
PDF Card for FeO (01-073-2144)


               This window may be closed to return to the
               previous graphical plot of ‘a’ vs. atomic % Fe.




The ‘Experimental’ tab of this window shows (among other
things), the source of the information. Authors, in this case,
are B.T.M. Willis & H.P. Rooksby.
        FeO a0 Cell Parameter vs. Atomic % Fe

                                                  Stoichiometric – 1:1
                                                 Stoichiometric – 1:1
                                  High Temperature
                                  High Temperature




                                                  Ambient
                                            Ambient




Choosing another entry from the graph (circled in blue), one
can bring up the information shown on the next slide.
PDF Card for FeO (01-074-1880)




Fe.9536O



 Reported stoichiometry for this
 entry is shown on the ‘PDF’ tab.
PDF Card for FeO (01-074-1880)
                      Close window to return to
                      search results graph.




         The reference shown on the
         ‘Experimental’ tab, for this entry,
         cites a study by E.R. Jette & F.
         Foote.
                   FeO a0 Cell Parameter vs. Atomic % Fe
                                                            Stoichiometric – 1:1

                                               High Temperature




                                     Ambient




                                           1 2 3 4 5 6 7 8 9

                                                    Formula     Reference
A number of points on this graph               1.   Fe0.942O    Willis & Rooksby
                                               2.   Fe0.9536O   Jette & Foote
appear to be linearly aligned with
                                               3.   Fe0.9570O   Jette & Foote
the two examined thus far.                     4.   Fe0.9630O   Jette & Foote
One could check the references                 5.   Fe0.9646O   Jette & Foote
of these points to determine if                6.   Fe0.9712O   Jette & Foote
                                               7.   Fe0.9712O   Jette & Foote
they are from the same sources.
                                               8.   Fe0.974O    Willis & Rooksby
                                               9.   FeO         Jette & Foote
    Combining the FeO Data from Just the Willis &
        Rooksby and Jette & Foote Sources

• To analyze the apparent relationship within the roughly linear data
  identified in the previous slide, the data must be limited to just
  the sources identified.
• A particular author can be added to the search criteria to restrict
  results to just that author.
• Results of multiple searches can be combined, such as results
  found from two different sources.
• This process is outlined here and illustrated on the next few slides:
    – Add author ‘Willis’ criterion to previous FeO search and perform search
    – Change author ‘Willis’ to author ‘Jette’ and perform search again
    – Combine results from these two searches via the ‘History’ tool
                 Search FeO Structures for Author ‘Willis’
   With the ‘Just (Fe And O)’ and ‘Space Group #225’ still in place on
   their respective tabs on the ‘Search’ window, the author ‘Willis’ can
   be added to the ‘References’ tab and the search performed.




                            2 Results


The results of this, and any other ‘Search’, are automatically saved in the
‘History’ file and can be accessed for the duration of the DDView session.
               Search FeO Structures for Reference ‘Jette’
Similarly, a second search is performed substituting author ‘Jette’ for
‘Willis’ of the previous search.




                             7 Results
       Use of the ‘History’ Tool to Combine Searches




The ‘History’ feature is accessed via the ‘Tools’ menu.
               Combine the Results of These Two Searches




The top area shows a history of searches performed during
this session. These searches may be individually selected and
copied to the searches may be combined with ‘And’ to arrow
The selected ‘Combined Searches’ area via the down include
only those entries that appear in both selected or with ‘Or’ to
button. Alternatively, they can both be searches using ‘Ctrl-click’
and copiedentries that appear in either search. For this
include all together via the down-arrow button.
exercise, we are interested in all entries, so ‘Or’ is chosen,
then the ‘Combined Results’ button performs the operation.
Combined Author Results for FeO Entries
            The results table includes all 9 entries,
            which may be graphed similarly to the
            way the original 63 hits were graphed.




                              ‘Atomic % Fe’ vs. ‘XtlCell-a’

                              Click ‘OK’ to create graph
                   Graph of FeO Cell Parameters derived by
                     Willis & Rooksby and Jette & Foote




These data may be exported to a ‘.csv’ file for more involved
mathematical or statistical analysis using a spreadsheet program. For
example, one could explore whether these data are linear (Vegard’s Law)
or if there is a systematic (and significant) deviation from linearity.
                         FeO a-axis Cell Parameter vs. Atomic % Fe
                               - High Temperature Studies

                                                    Stoichiometric – 1:1
                                           High Temperature




                                                          Ambient




Several entries from this high temperature region reference
a single study, “Point Defect Clusters in Wuestite” by Radler,
Cohen, & Faber, J. Phys. Chem. Solids, 51, 217 (1990). To
quickly examine which points come from this study, the
search can be reperformed using one of these authors.
  Change Author for Search




On the ‘References’ tab, ‘Radler’ (or
‘Cohen’ or ‘Faber’) can be entered in the
‘Author’ field to obtain the desired PDF
entries. The ‘Structures’ and ‘Periodic
Table’ tabs contain the previously
entered information regarding FeO and
space group 225. This search will yield
the 13 entries found on the next slide.
PDF Entries from Radler, Cohen, & Faber Study (1990)




        The a-axis cell parameter for just these
        entries can now be plotted vs. atomic % Fe
        and the resulting graph is shown on the
        following slide.
                   Graph of Radler, Cohen, and Faber FeO Entries




                                1




                        2




1. Data for varying T from 1123 to 1373 C with slightly increasing O content

2. Data for varying stoichiometry at 1323 C from Fe0.88O to Fe0.95O
                                 Another Look at FeO results - Density
Return to the original list of 63 FeO entries . . .

                                          Choose the original search:
                                          {Only (Fe And O)} And {International
                                          Space Group Number Exactly ‘225’}
                                          and click the ‘Results’ button.




 Use the ‘History’ icon to
 retrieve any searches already
 performed during this session
 of DDView+.
Another Look at FeO results - Density
            Another way to analyze this data is to
            look at the density as a function of cell
            parameter. This is performed by using the
            ‘Results’ drop down menu to access
            ‘Graph Fields…’
                              Results: density vs. a axis cell
                            parameter for reported FeO structures



                                             Entries with 1:1 atomic ratio reported for FeO
                                             Density is inversely proportional to cubic cell parameter




                                           “An -ray Study of the Wuestite (FeO) Solid Solutions”
                                           - Jette & Foote & “Change of Structure of Ferrous
                                           Oxide at Low Temperature” - Willis & Rooksby.
                                           Density increases very slightly as cell parameter goes
                                           up with increasing Fe content.
“Point Defect Clusters in Wuestite” - Radler, Cohen, & Faber
Density decreases as a axis increases (inverse relationship) as T
is varied from 1123 to 1373 C with slightly increasing O content
Both density and a axis increase dramatically as stoichiometry
at 1323 C is increased from Fe0.88O to Fe0.95O.
     Summary for Non-stoichiometric Cubic FeO

• Multiple explanations exist for unit cell parameter
  variations in non-stoichiometric FeO in the PDF
• Systematic studies regarding stoichiometry and/or
  temperature can be “mined” from the database
• No single relationship describes all the data, thus
  different “defect” arrangements must exist for these
  materials
• Ability to access PDF entries directly from graphs’
  facilitates obtaining other data and references
   Thank you for viewing our
tutorial. Additional tutorials are
 available at the ICDD web site
        (www.icdd.com).




              International Centre for Diffraction Data
                        12 Campus Boulevard
                     Newtown Square, PA 19073
                        Phone: 610.325.9814
                          Fax: 610.325.9823

				
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posted:10/13/2012
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