Transcript Examples Exploiting Extra Features in DDView

Data Mining with DDView+
and the PDF-4 Databases
Solid Solution Crystal Cell Parameters
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:
• CIGS Photovoltaics
– solid solution / cell parameter relationship
Two other similar tutorials for data-mining exist and
cover the following topics:
• FeO Non-stoichiometric Oxides
– sorting out temperature and stoichiometric effects
on cell parameters
• Carbamazepine Polymorphs
– a PDF-4+/Organics application
– investigating polymorphic forms of an active
pharmaceutical ingredient (API)
CIGS Photovoltaics
• CIGS = Cu (In, Ga) Se2 - ( 1 : 1 : 2 )
• Record-breaking light-energy conversion
efficiency for film-based photovoltaics, ~20%
• Several methods of manufacture
• Efficiency depends on stoichiometry
Can stoichiometry be evaluated by XRD?
CIGS Data Mining
Process Steps
1. Find the PDF-4+ entries for CIGS solid
solution phases
2. Obtain chemical composition, space group,
and crystal cell parameters from entries
3. Determine relationship between chemistry
and crystal cell parameters, if any
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 categorized items and the ‘Selected
Fields’ list of items that will be displayed in the results table.
Using the described arrows, set up the ‘Selected Fields’ list
to match the following:
PDF File Reference #
Quality Mark
Ambient Conditions Flag
Chemical Formula
Crystal System
Space Group
Space Group # (Int. Tables)
Crystal Cell a-axis length
Crystal Cell c-axis length
Calculated Density
Once the ‘Selected Fields’ list is set up as shown, click the ‘OK’
button to save changes and close the ‘Preferences’ window
Save changes and exit ‘Preferences’ window.
Save changes,
but do not exit
‘Preferences’
window.
• The ‘Search’ window is used to enter criteria for locating database entries of
particular interest.
• There are seven different tabbed windows of search criteria available.
• Click on the ‘Periodic Table’ tab to enter elemental criteria for this search.
CIGS Photovoltaics: {Cu (In, Ga) Se2}
[The sequence for specifying “Only (Cu And In And Ga And
Se)” will be shown as you continue to click this slide]
Finally click ‘Add’ to include
this criterion for the search.
Then click ‘Only’ . . .
First click these four elements . . .
Activating the search: Cu (In, Ga) Se2
Note this tab label has turned
red, which denotes that search
criteria now exist on this page.
Verify the proper entry of the
elemental criterion here . . .
. . . and click ‘Search’ to retrieve the PDF4+ entries that satisfy this criterion.
CIGS Retrieval (Only Cu, In, Ga, Se) Results Table
• All listed entries belong to the Cu (In, Ga) Se2 solid solution series except
00-051-1222 which is Cu (Ga, In)3 Se5.
• Except for 00-051-1222, all belong to tetragonal space group I-42d (#122).
(Note a ~ 5.7Å and c ~ 11.3Å for all entries.)
• PDF entries 04-005-8370 and 04-006-4510 are from the LPF database (04)
and thus contain the crystal structure complete with atomic coordinates.
• An entry is viewed by double clicking on its row in the table. We’ll examine
this one.
This window provides access to all database information for this entry.
The crystal structure is viewed by clicking the circled ‘atomic structure’ icon.
The resulting window gives a choice of structural views. Clicking the
first one will show a rotatable 3D view that fills the window.
Structure View Window
Use a right mouse click to bring up the structure view manipulation menu.
This determines the action of left mouse click-and-drag.
Through appropriate X/Y-axes
rotations one can obtain the
end-view perspective of the
tetragonal cell shown above.
CIGS Photovoltaics
• To get a complete perspective of cell parameter relationships for
the solid solution series, it would be advantageous to include the
end-members of the series, namely CuInSe2 and CuGaSe2.
• These can be included by modifying the search as follows:
– Periodic Table:
• [And] Cu And Se - must have both
• [And] In Or Ga - must have at least one
• [And] Just Cu, Ga, In, Se - no other elements but these
– Space group: #122 (I-42d)
– Database filter: Primary patterns*
• Additionally, the ‘atomic %’ field should be included in the results
table for examining In-Ga concentration dependencies.
 The next few slides will guide you through this process.
* There are numerous entries for the end-member compounds, this will limit
the results to those determined as best by the ICDD task groups and editors.
Add ‘Atomic %’ to CIGS Search Results Preferences
Add Atomic % to Selected
Fields for Results Table
Add ‘Atomic %’ to CIGS Search Results Preferences
Add Atomic % to Selected
Fields for Results Table
Enter New Search Criteria
Before entering new criteria, clear the previous search criterion by clicking
the ‘Reset All’ button.
Enter new search criteria (Page 1):
“Primary” pattern status is selected on the “Subfiles / Database Filters” page
Enter new search criteria (Page 2):
International Space Group (#122) is selected on the “Structures” page
Enter new search criteria (Page 3):
 Enter required elements on “Periodic Table” page: (Cu And Se)
Enter new search criteria (Page 3):
Enter required elements: (Cu And Se)
 Enter solid-solution elements: (In Or Ga)
Enter new search criteria (Page 3):
Enter required elements: (Cu And Se)
Enter solid solution elements: (In Or Ga)
 Restrict chemistry to these 4 elements: Just (Cu And Ga and In and Se)
Enter new search criteria (Page 3):
Verify chemistry criteria and start search.
• Verify chemistry criteria
• Click ‘Search’
CIGS Search Results Including Atomic %
32 Resulting Entries
4 are CuGaSe2 (2 experimental, 1 ICSD, 1 LPF)
24 are CuInSe2 (1 experimental, 22 ICSD, 1 LPF)
4 are Cu(In,Ga)Se2 (3 experimental, 1 LPF)
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 using an X-Y plot to illustrate
cell parameters as a function of atomic % Ga.
To do this, ‘Graph Fields…’ is first selected from the ‘Results’ dropdown menu of the ‘Results’ window.
Choose X-axis field
from drop-down
menu: Atomic %
Choose element for
Atomic % values: Ga
Choose Y-axis field
from drop-down
menu: XtlCell-a
Click ‘OK’ to
draw Graph
Cu (In, Ga) Se2 - ao Cell Parameters vs. At % Ga
a0
The data, extracted in this manner from the PDF-4+ database, clearly
illustrate the linear relationship of the a-axis lattice parameter of CIGS
compounds with atomic % Ga in the structure.
At 0 atomic % Ga, the a-axis is ~5.78Å, while at 25 atomic % Ga
(CuGaSe2 where gallium is ¼ of the atoms in the formula), the a-axis
is ~5.61Å.
Similarly, data for the c-axis cell parameter can be plotted.
Using the same Ga atomic % values for the X-axis, the
XtlCell-c data field can be chosen for the Y-axis.
Y-axis Field: XtlCell-c
Click ‘OK’ to display graph
Cu (In, Ga) Se2 - Cell Parameters vs. At % Ga
c0
Again, a linear relationship of the c-axis lattice parameter of CIGS
compounds with atomic % Ga in the structure is clearly illustrated.
At 0 atomic % Ga, the c-axis is ~11.61Å, while at 25 atomic % Ga, the
c-axis is ~11.02Å.
Cu (In, Ga) Se2 - Cell Parameters vs. At % Ga
Results can be exported as a
comma-delimited text file for
use in a spreadsheet program.
Cu (In, Ga) Se2 - a-axis Cell Parameter vs. Ga At %
Linear Regression via Excel Spreadsheet*
Rearranging, At % Ga = -145.808 * a (Å) + 843.1761
* Use a spreadsheet or data analysis program of your choice
Cu (In, Ga) Se2 - c-axis Cell Parameter vs. Ga At %
Linear Regression via Excel Spreadsheet *
Rearranging, At % Ga = -41.6505 * c (Å) + 483.8731
* Use a spreadsheet or data analysis program of your choice
CIGS Summary
• Crystal cell parameters for CIGS compounds,
Cu(In,Ga)Se2, can be effectively “mined” from the
PDF-4+ database
• These can be plotted as a function of Ga (or In) At %
to show a relationship
• Equations useful for determining At % Ga from
ray-derived cell parameters can be generated
• At % Ga = -145.808 a (Å) + 843.1761
• At % Ga = -41.6505 c (Å) + 483.8731
• A single, indexed powder diffraction pattern can
provide two determinations of At % Ga
X-
Thank you for viewing our tutorial.
Additional tutorials are available at the ICDD website
(www.icdd.com).
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