Data Mining with DDView and the PDF4 Databases

1
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
2
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)

3
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.

4
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.
5
Data Mining for FeO Entries Step 1 Use the
Preferences Window to establish what will be
displayed in the Search Results table . . .

• Click the Preferences icon
• Click the Search tab in the Preferences window

• Click the Preferences icon

6
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.
7
Selecting Fields for Results Table (FeO)
Setting up the fields as shown here will serve
the purposes of this example.
8
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 . . .
9
Structure Criterion for Search FCC Space Group
225 Fm-3mentered on Structures tab of
Search window
Perform search using specified chemistry and
space group criteria.
10
Results of DDView Search for FeO
A total of 63 entries for Fe1-xO compounds
11
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.
12
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
13
FeO a-axis Cell Parameter vs. Atomic Fe
Stoichiometric 11
High Temperature
Ambient

• This graph shows little apparent correlation
  between atomic Fe and a-axis.
• Note that entries reported as being
  stoichiometric (11) 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.

14
PDF Card for FeO (01-073-2144)
Fe.942O
The PDF tab of this window displays the actual
formula and stoichiometry.
15
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.
16
FeO a0 Cell Parameter vs. Atomic Fe
Stoichiometric 11
Stoichiometric 11
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.
17
PDF Card for FeO (01-074-1880)
Fe.9536O
Reported stoichiometry for this entry is shown on
the PDF tab.
18
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.
19
FeO a0 Cell Parameter vs. Atomic Fe
Stoichiometric 11
High Temperature
Ambient

• Formula Reference
• Fe0.942O Willis Rooksby
• Fe0.9536O Jette Foote
• Fe0.9570O Jette Foote
• Fe0.9630O Jette Foote
• Fe0.9646O Jette Foote
• Fe0.9712O Jette Foote
• Fe0.9712O Jette Foote
• Fe0.974O Willis Rooksby
• FeO Jette Foote

A number of points on this graph appear to be
linearly aligned with the two examined thus
far. One could check the references of these
points to determine if they are from the same
sources.
20
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

21
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.
22
Search FeO Structures for Reference Jette
Similarly, a second search is performed
substituting author Jette for Willis of the
previous search.
7 Results
23
Use of the History Tool to Combine Searches
The History feature is accessed via the Tools
menu.
24
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
Combined Searches area via the down arrow
button. Alternatively, they can both be selected
using Ctrl-click and copied together via the
down-arrow button.
The selected searches may be combined with And
to include only those entries that appear in both
searches or with Or to include all entries that
appear in either search. For this exercise, we
are interested in all entries, so Or is chosen,
then the Combined Results button performs the
operation.
25
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
26
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 (Vegards Law) or if there is a systematic
(and significant) deviation from linearity.
27
FeO a-axis Cell Parameter vs. Atomic Fe - High
Temperature Studies
Stoichiometric 11
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.
28
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.
29
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.
30
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
31
Return to the original list of 63 FeO entries . .
.
Another Look at FeO results - Density
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.
32
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
33

• Results density vs. a axis cell parameter
  for reported FeO structures

Entries with 11 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.
34
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

35
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 [phone]