ICDD PDF-4+ 2012 Instructions

ICDD PDF-­‐4+ and SIeve+ Software
Contents
Setting up your data ................................................................................................................... 3
Setting up Preferences ................................................................................................................ 4
Searching the Database .............................................................................................................. 5
Starting SIeve+ and loading your data ....................................................................................... 7
Multi-phase samples .............................................................................................................. 8
Publishing your final analyses ................................................................................................... 9
Common problems ................................................................................................................... 11
‘I have found a card with peaks in similar positions, but shifted to higher/lower angle’ .... 11
‘The intensities on the PDF card are odd – they’re all multiples of 10, or 20!’ .................. 11
Phase analysis in action: Examples .......................................................................................... 12
Example 1: Titanium dioxide ............................................................................................... 12
Example 2: Nb,Cu-doped Titanium dioxide ........................................................................ 15
Example 3: Two-phase mixture of NaCl and Si .................................................................. 18
Example 4: Data Mining ...................................................................................................... 20
Further Reading ....................................................................................................................... 23
References ................................................................................................................................ 23
Appendix 1: Conversion of ‘old’ to ‘new’ format PDF Card Numbers .................................. 24
Appendix 2: Quality Marks ..................................................................................................... 25
This software is only licensed for use on one computer. It is
not available for users to install on other computers.

Last updated: NRM, 07/03/2013

Setting up your data
The first thing you need to do is to set up your experimental powder diffraction data for
analysis. In order to load your experimental data in to the SIeve+ software, it must first be
in one of the following data formats:
-­‐ *.csv (as output by the Siemens D500 and Philips PW1825)
-­‐ *.dat (for the Siemens D5000s)
-­‐ *.xyd (for all other instruments)
For data collected on the Siemens D5000s:
1. Open the program ConvX
2. Choose File Type: DiffracPlus Raw
3. Select File(s) to convert (can multi-­‐select files where identical scan parameters used)
4. Set Output file details to ‘Files of Type’ = ASCII 2theta,I
5. Check Output Parameters boxes filled in appropriately
6. Press ‘Do That Convert Thang!!’ button and check for any files skipped.
For data collected on the STOE Image Plate:
1. In WinX POW , go to Raw Data/Raw Data Handling
2. Go to File/Open, and select your file
3. Click Ranges/Add Ranges – add ranges 2 and above to range 1
4. Click Ranges/Extract Ranges – extract range 1, to a file with format .ra1
5. Click File/Export, and select the *.xyd file format option
For data collected on the STOE PSD systems:
1. In WinX POW , go to Raw Data/Raw Data Handling
2. Go to File/Open, and select your file
3. Click File/Export, and select the *.xyd file format option
You can also import data in GSAS format by specifying the start and stop angles, step size,
the number of data points per line, the line number where data start, and the wavelength.

Setting up Preferences
The next step is to ensure that the PDF-­‐4+ 2012 software is set up appropriately for the
experiment that you performed.
1. Click on the ‘PDF-­‐4+ 2012’ icon on the desktop of the computer to launch the
software, if not already running.
2. At the top of the screen, click the Edit menu, then choose Preferences.
3. In the PDF Card tab, ensure that the ‘Wavelength’ matches that of your experiment.
4. Click on the Simulated Profile tab and make sure that again the Type and Anode
match your experiment (i.e. Type = Ka1 or Ka1+2 and Anode = Co, Cu or Mo as
appropriate).
5. Also on the Simulated Profile tab, check how the ‘Profile’ is being calculated for
simulated line shapes. An easy way to simulate sharper Bragg lines is to use a larger
‘Crystallite Size’ with ‘Mean Crystallite Diameter’ of 500.0 nm or higher; conversely,
using a smaller ‘Mean Crystallite Diameter’ will calculate a broader line shape.
6. At the bottom of the Simulated Profile tab, you can also select the Ranges displayed
for simulated profiles.
7. On the SIeve+ tab, set the desired Search Method (typically Hanawalt), Search and
Match Windows (typically 0.18), Lowest Allowable GOM (1000-­‐2000, lower will allow
more ‘false positives’) and Wavelength (as appropriate)
8. Click OK.

Searching the Database
The database can be accessed by clicking on the ‘PDF-­‐4+ 2011’ icon on the desktop of the
computer.
There are a multitude of search criteria – I would encourage you to play around and see
what things do. As a brief summary, you can search by the following general criteria:
• Database (there are actually several included)
• Ambient or non-­‐ambient temperature/pressure
• Quality Mark (S, R, I are more reliable)
• Subclass (e.g. cements, ceramics…)
• Elements (using Boolean logic or Yes/No/Maybe)
• Formula, composition & number of elements
• Name (compound, common, mineral)
• Zeolite or Mineral Classification
• References (author, journal, title, etc.)
• Structures (symmetry, space group, unit cell dimensions, (non)centrosymmetry,
atomic environment (e.g. tetrahedral, etc.))
• Lines at specific low angles (‘long lines’) or intense peaks (‘strong lines’)
• Density
• Melting point
• I/Ic (for RIR method of quantitative phase analysis)
• Organic functional groups…
Those italicised are recommended, but not essential. Those in bold should be considered
essential.

To filter through the database:
1. Go to the main ‘Search’ window
2. Choose your filtering criteria – a good starting point might be to select those
elements present in your sample. To do this:
a. Select either the Boolean or Yes/No/Maybe tab; I prefer the latter, so we’ll
do that here.
b. Click Set Unselected to ‘No’ – this will deselect all elements
c. Click an element to add it to the ‘Maybe’ list (i.e. this element may or may
not be in the phases in your sample). Clicking it again will add it to the ‘Yes’
list (i.e. this element must be in all the phases in the sample). A third click
will return it to the ‘No’ list.
d. Repeat for all elements as appropriate.
3. Repeat for other search criteria if and where appropriate.
4. Once you are happy with the search criteria, click Search at the bottom of the
‘Search’ window. A ‘Results’ list will appear in a new window.
5. Double-­‐clicking on any of the results in the list will open that PDF Card up in a new
window.
You can also search for specific PDF card numbers:
1. In the main PDF-­‐4+ 2012 menubar, click File and then Open PDF Card...
2. Enter the card number...
If you wish to search for a PDF card in the old 6 digit XX-­‐XXXX PDF card number, you will
need to convert it to the new 9 digit PDF card number format – see Appendix 1.

Starting SIeve+ and loading your data
We should now have the software open, and set up to look at the data collected during your
specific diffraction experiment.
1. At the top of the PDF-­‐4+ 2012 screen, click Tools, and then SIeve+
2. In the SIeve+ window, choose File, then Import Diffraction Pattern
3. Select your *.csv, *.dat or *.xyd file. Another window appears!
a. Note: If using a (D5000) *.dat file, there will be a warning that you’re being
kicked in to the Advanced Experimental Data Importer – this is because you
have a comment in Line 1. Under ‘Delimiter’ set the Start Line to 2.
4. Select the appropriate wavelength for your data
5. Click Show Graph. Make it matches what you actually did (correct 2θ range etc.)
6. Click Process Data
7. Another window opens! Here you can remove the background, smooth the data,
and remove Kα2 peaks. So far, I have found using the default options OK, though
those with significant amorphous (e.g. glassy) components may need to be more
careful: press Remove, then Smooth if necessary
8. Kα2 stripping:
a. If your data were collected on the PW1825, D500 or D5000s, zoom in on high
angle lines and check to see if you are resolving the Kα2 peaks. If so, press
Strip Kα2, but be careful of introducing artefacts in to your data.
b. If the data were collected on the STOEs, instead press Skip>
9. You should notice that the Plot Preview in the Import screen has updated with tick
marks indicating your peak positions. SIeve+ will use these tick marks to try to
identify what phase(s) are present in your sample. If you’re happy with the tick
marks chosen, press Accept Peaks. If not, repeat the process or use the Manual
Peak Selection controls to add or remove peaks. This is the key stage so it is vital you
do this well.
10. Click Import

11. Click on the appropriate Past Search Filter to select a relevant subsection of the
data.
12. Click Apply Filter and wait while the software searches for matches. Clicking ‘No
Filter’ to search against the full database.
A list of results appears, ranking the database entries in the order in which they most closely
resemble your data by some ‘Goodness of Match’ score. This does NOT mean that the top
result is definitely a match for your sample – just that its XRD pattern most closely matches
your experimental data. It is much more important that the chemistry matches what is
reasonable or expected for your sample!
Double-­‐clicking any entry in the list will display the PDF database card for that entry.
To reiterate: you will now have a list of possible matches to your sample, organised by the
‘Goodness of Match’ score – bear in mind that the software only knows what you tell it
about your specimen, and so the top answer is NOT necessarily correct – garbage in,
garbage out!
You can also add a specific PDF card number to the list in SIeve+ if you wish to compare
against something specific:
1. In the SIeve+ window, click on the Matches menu
2. Click Add PDF ...
Multi-­‐phase samples
Follow all the instructions in the previous sections!
If you have a multi-­‐phase sample, you can then click on the ‘handshake’ button at the top of
the SIeve+ window to accept a card that you think is a good match for one of the phases in

your sample. The software will then look for the next best matching phase (assuming you
have made your filter criteria quite general).
Once all the peaks in the diffraction pattern have been accounted for, the software may be
able to use the RIR method to give an estimated of the quantity of phases present –
providing the cards you have selected all have an I/Ic value entered – many do not.
I/Ic is the height of the strongest reflection in the pattern (the 100% reflection) expressed as
a ratio to that of corundum, a-­‐Al2O3. I/Ic is obtained by preparing a 50:50 mixture (by
WEIGHT) of the phase with corundum and measuring the strongest reflection from the
phase and from corundum as obtained from the mixture.
The RIR method is relatively easy, but can be very inaccurate. There is a tutorial about it on
the ICDD website here which those considering it should probably read. You definitely need
randomly orientated powder samples, and it only gives ratios not absolute amounts. If you
want a more accurate quantification, you really need to use the Rietveld method.
Publishing your final analyses
Once you’ve satisfactorily finished your phase analysis, you should have a fitted graph that
you want to export in to some format that you can take elsewhere and view as a picture or
paste in to a report, etc.
The best way I have found to do this within the software is...
1. In the SIeve+ window, go to the Phases menu and Open Simulated Profile with
Experimental Data
2. In the window that appears, click Edit and then Preferences
3. In the PDF Card tab, ensure that the ‘Wavelength’ matches that of your experiment.
Click on the Simulated Profile tab and make sure that again the Type and Anode

match your experiment (i.e. Type = Ka1 or Ka1+2 and Anode = Co, Cu or Mo as
appropriate).
4. If you wish to export the selected PDF card(s) as simulated profile(s), the easiest and
quickest way to broaden the simulated profile peaks to more closely match yours is
to click on the Simulated Profile tab and change the ‘Profile’ setting from Pseudo-­‐
Voigt to Crystallite Size and change the Mean Crystallite Diameter from e.g. 25 to
250 – play around and see. This does not imply anything about the crystallite size in
your specimen! Click OK.
5. If you wish instead to export the selected PDF card(s) as stick traces (i.e. peaks with
no width), click Plots and Add Stick Trace. Enter the correct PDF Card number, and
click Open. Click OK to accept the default ‘Fixed Slit Intensity’ type. Finally, click
Plots, Delete, and select the entry for the full simulate profile – this will be the one
with the full stoichiometry, PDF card number AND comments about Experimental
Intensity). Click OK and then Delete.
6. Repeat if and as appropriate for other PDF card(s).
7. Once you are satisfied, click File, Save. Change ‘Files of Type:’ to JPEG and give a file
name. This JPEG will be an image file that you can then view or import in to Word,
Powerpoint etc. as a picture file.

Common problems
‘I have found a card with peaks in similar positions, but shifted to
higher/lower angle’
This can have three possible causes:
1. Sample height displacement – even a small error in the height of the sample will
have an impact on peak position. This error may appear fairly linear with diffracted
angle. This is a very common, but largely avoidable, problem. Run the sample again,
with more attention to correct sample height.
2. Wrong wavelength selected – either when importing the data (copper is the default),
or in Search/Match (other people may have changed this). If the peak shift is
dramatically different, this may be the cause.
3. Change in chemistry – if you can replace an element in the crystal structure with
another, this is likely to cause changes in the shape and size of the unit cell. You may
get the same pattern of peaks, but shifted to higher or lower angles. In this case, the
shift is likely to be small at low angles, and significantly larger at higher angles.
‘The intensities on the PDF card are odd – they’re all multiples of 10, or 20!’
This would indeed be quite odd for a real sample! Most likely the data have been collected
using an old photographic film technique; check the card text entry for the method used –
perhaps it says a Guinier diffractometer was used, or that intensities were obtained via
‘visual’ or ‘densitometer’ methods. Such techniques are extremely accurate; however, the
ability of the researcher to accurately interpret the data is more limited! Use such cards
with caution.

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 PDF 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 PDF
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

patterns, which reduced the number of cards returned to 431. Opening SIeve+, I imported
and digitised my experimental diffraction data and automatically applied my filter.
The top card, with a GOM score of 3259, was card 04-­‐014-­‐0245 – no mineral name was
listed for this entry, but the crystal system was ‘Tetragonal’, and the space group P42/mnm.
Comparing with other cards that also gave a good match proved that this card, and my
specimen, were indeed rutile-­‐structured:

Example 2: Nb,Cu-­‐doped Titanium dioxide
In the same research project, I used this TiO2 as a reagent, along with CuO and Nb2O5, to
investigate the possible formation of a rutile-­‐structured solid solution series, Ti1-­‐3xCuxNb2xO2.
Appropriate amounts of each reagent were mixed in an agate mortar and pestle, then fired
in Pt foil boats at 935 ºC for 60h with intermittent regrinding. I then used the imaging plate
detector on our Cu-­‐STOE system for phase analysis.
Compositions (data shown below, in WinX POW ) with x = 0.01–0.23 yielded phase-­‐pure
samples, which were indexed using the rutile space group, P42/mnm, showing that co-­‐
doping of TiO2 with Cu and Nb was possible:
Comparison against the previous example will show that the first five reflections for the
rutile are present and correct here for samples with x = 0.05, 0.13 and 0.20. No other
additional reflections are observed; these samples are phase pure. Note how the rutile
peaks are shifting to lower angles, i.e. higher d-­‐spacings, as x increases. As I replace Ti 4+
with the larger Cu 2+ and Nb 5+ cations in my structure, the unit cell size is increasing. For a
solid solution, generally, unit cell parameters should change linearly with composition – a
phenomenon known as Vegard’s Law. In this case, the a and c cell parameters deviate away
from linearity, but the cell volume does increase linearly with composition (see N. Reeves-­‐
McLaren et al, “Synthesis, structure and electrical properties of Cu3.21Ti1.16Nb2.63O12 and the

CuOx–TiO2–Nb2O5 pseudoternary phase diagram”, Journal of Solid State Chemistry, 2011 for
further details of this study).
The rutile peaks are also present in the other two histograms, for x = 0.242 and 0.286;
however, they are no longer shifting with composition. In addition, we also see extra
reflections – most notably at around 24 and 30 º2θ. In combination, these data show that
the limit for solid solution formation (in samples prepared at 935 ºC as these were, at least)
lies between x = 0.20 and x = 0.242; in this example, I will work on the data for x = 0.286, to
make the presence of the secondary phases obvious.
The indexing of these Bragg reflections from secondary phases was initially informed by the
pseudoternary phase diagram, on which I was working. Previously reported phases with
compositions closest to those of my two rogue samples were obvious candidates to check
first – there were a number of copper niobate and titanium niobate phases listed in the
Powder Diffraction File.
Loading my data file in to SIeve+, I based my initial search filter on what I suspected from
where the composition lay in the pseudoternary phase diagram; I was expecting to see
phases that definitely contained Cu, Nb and O, and might also contain Ti. This returned 24
cards. The software immediately identified a monoclinic CuNb2O6 phase, which gave a good
match for many of my observed reflections. After accepting this card (04-­‐014-­‐9621), the
software pulled up a second, orthorhombic polymorph of CuNb2O6 – this was anticipated,
from literature reviews, as these two phases always co-­‐exist. I accepted this card by again
clicking the handshake button.
No further results were returned. However, there were still additional unindexed
reflections in my data. From my other studies, I knew from the pattern that this was my
doped rutile phase – only one such phase was listed in the database, ‘Cu0.5Ti0.5NbO4’ (x =
0.20) in PDF card number 00-­‐046-­‐0524. In the SIeve+ window, I went into the ‘Matches’
menu, and chose ‘Add PDF #...’, and entered this card manually. The peaks appeared, and
are a little way off mine – this is to be expected, since the rutile phase in my specimen has a

slightly different composition (which we could calculate from its lattice parameters, if we
wanted to).
I was then satisfied that my sample contained a rutile phase, whose composition could be
calculated from its lattice parameters, and both the orthorhombic and monoclinic forms of
CuNb2O6. This information could then be fed in to the construction of my pseudoternary
phase diagram. Unfortunately, that mismatch on the rutile peak positions most likely
rendered the quantification provided by SIeve+ untrustworthy.

Example 3: Two-­‐phase mixture of NaCl and Si
In a 2011 training school, students were asked to perform quantitative phase analysis using
the Rietveld method on a specimen that I had prepared. The specimen was 0.0641g NaCl
and 0.0183g Si, therefore 77.79 wt% NaCl, 22.21 wt% Si. The Rietveld method is the best
method for quantitative phase analysis, and the students were able to determine the
correct phases to within a couple of wt%.
I repeated the experiment using the SIeve+ software. I applied three basic filters: Na, Si
and Cl were set to ‘Maybe’, all other elements were set to ‘No’, and the total number of
elements in each card was to be 1 or 2 (this can be set in the ‘Elements’ tab).
SIeve+ found the NaCl straight away:
I accepted this card by clicking the handshake icon. SIeve+ then found the Si automatically –
bear in mind that this is great data collected on a well-­‐prepared specimen of two things with
simple crystal structures!

By also accepting the Si card, SIeve+ was also able to use the RIR method to give a
quantification of the two phases, which is listed under I% near the bottom.
SIeve+ was suggesting that the sample was 74 wt% NaCl, 26 wt% Si. Not a bad estimate –
but bear in mind that the answer is good because we are expecting this answer… and that
the errors inherent in the RIR method still apply.

Example 4: Data Mining
The PDF-­‐4+ 2011 software allows for some interesting and potentially useful data mining
applications. As an example of the sort of thing that is possible, let us consider a study of
the NaCl-­‐KCl solid solution series, Na1-­‐xKxCl. One thing we know about solid solutions is that
they often follow Vegard’s Law, i.e. that the lattice parameters show a linear variation with
composition.
There are a lot of entries in the PDF-­‐4+ 2011 database that would be relevant to this study,
which will all have relevant lattice parameters listed… but how can we mine this data?
Let us first set up our search filters. I’m only interested in good quality data collected at
ambient conditions. I don’t want any high temperature/pressure data! I therefore set up
the following filters on the Subfiles/Database Filters tab:
- those cards not deleted by ticking the ‘not’ tickbox, and then clicking ‘Deleted’
- those datasets collected under ambient conditions
- those cards of ‘Star’, ‘Rietveld’ and ‘Indexed’ quality marks (using shift key and click
to multi-­‐select)

Next, I select the elements of interest by going to the ‘Periodic Table’ tab, and the
‘Yes/No/Maybe’ subtab. I ‘Set Unselected to ‘No’’ and then single-­‐click ‘Na’ and ‘K’ to add
them to the Maybe list; I double-­‐click ‘Cl’ to add it to the ‘Yes’ list.
Finally, as I don’t want to find Cl on its own, but only in combination with either Na or K, I go
to the Elements tab and under ‘Number of Elements (#El’s) I select 2 and 3, again using shift
key and click to multi-­‐select. When I click Search, a ‘Results’ child window appears listing all
of the appropriate KCl, NaCl and Na1-­‐xKxCl database entries.
I want to do some advanced stuff here, so I click ‘Edit’ and then ‘Preferences’. Because I
want to look at how the lattice parameters vary with composition in these results, I need to
add two ‘fields’ from the available fields list to the selected fields list: ‘Atomic%’ and
‘AuthCell Vol’ for the composition and cell volume parameters, respectively. ‘Atomic%’ is
listed under ‘+Elements’, while the cell parameters options are listed under ‘+Structures’.
To add them to my Selected Fields list, I simply find and highlight them, then click the big
blue ‘>’ button, then click OK when done.

Back in the ‘Results’ child window, I click in to the ‘Results’ menu and then ‘Graph Fields…’.
On the X-­‐axis, I select ‘Atomic%’ from the drop down menu, and then set the Element to ‘K’.
For the y-­‐axis, I select ‘AuthCell Vol’. Then I click ‘Create Graph’. A graph appears in a new
child window, and it is apparent that there are a couple of weird outliers in the data. I hold
the left-­‐mouse button to drag a box around the data of actual interest to me, which then
appears zoomed in:
From these data, it is apparent that, for this solid solution series, the lattice parameter
increases linear with K content in accordance with Vegard’s Law! Clicking on any of the data
points will open up the PDF card for that specific entry. Clicking ‘File’, then ‘Save’ allows you
to save in *.jpg format, or as a *.csv file for further analysis in e.g. Excel.
There are further examples of this process on the ICDD’s tutorial website, which can be
accessed via the software’s help menu. Of particular relevance are the tutorials on Data
Mining – Nonstoichiometric Oxides and Data Mining – Solid Solution. There are a lot of
potential pitfalls with this sort of analysis, which are well covered in these online resources.

Further Reading
The ICDD software has an extensive Help section which may be accessed via the software.
Also, clicking on the Help menu will show the Tutorial link – clicking on this opens up the
extensive array of online tutorial materials available on the ICDD website.
References
West, A.R., (1988). Basic Solid State Chemistry. John Wiley & Sons Ltd: Chichester.
Pecharsky, V.K. & Zavalij, P.Y., (2005). Fundamentals of Powder Diffraction and Structural
Characterization of Materials. Springer: New York.
Clearfield, A., Reibenspies, J. & Bhuvanesh, N., (2008). Principles and Applications of
Powder Diffraction. John Wiley & Sons Ltd: Chichester.
Hyatt, N.C., (2008). MAT255: X-ray Diffraction. Lecture course notes.
Help files attached to the ICDD PDF-4+ and SIeve+ 2011 software packages.

Appendix 1: Conversion of ‘old’ to ‘new’ format PDF Card Numbers
This is the identification number of the pattern in the Powder Diffraction File (PDF).
Traditionally, the ICDD has employed a logical numbering process for giving each
experimental PDF pattern a unique number. This is done by subtracting 1950 from the year
of a given annual update then adding a further 4 digits from 0001 to 2500 (typically). For
example, the first pattern in the 1997 update is 47-­‐0001 and the 2,500th is 47-­‐2500.
Collaborations with other database organizations, FIZ in Karlsruhe (the ICSD database) and
CCDC in Cambridge (the CSD database) and the National Institute of Science and Technology
(NIST) and the Linus Pauling File (LPF) have led to a dramatic explosion in entry population.
Provided the ICDD maintains the historical significance of experimental patterns in the PDF-­‐
2, the 6-­‐digit entry system did not contain enough space to house all of these new entries.
The solution was to add additional digits (an "area code") to the PDF number. The following
schema has been implemented:
The primary motive in this scheme is to leave the functional components of the PDF number
intact. As seen in the Table, the new 9-­‐digit code allows the ICDD to avoid overlapping PDF
numbers between those entries from the CSD and those from the ICSD. The PDF number
scheme was implemented for the first time in the PDF-­‐4/Organics 2003.
Entries may be cross-­‐referenced.
(Taken from Help files for PDF-­‐4+ 2012 software)

Appendix 2: Quality Marks
The editor of the PDF assigns the quality mark based upon an evaluation of the following
parameters:
• Formula checking including generation of an empirical formula.
• Form of the chemical name and comparison with the formula for consistency.
• Comparison of the measured, calculated, and estimated densities.
• Validation of space group, aspect, or lattice type with allowed symbols and assigned
crystal system.
• Generation of Pearson symbols for structure types.
• Refinement of d-­‐Spacings and confirmation of indexing with extinction rules for
space groups.
• The Smith-­‐Snyder and the deWolff figures of merit.
The following quality mark definitions are available:
• Star (S). Indicates the pattern represents high-­‐quality diffractometer or Guinier data.
• Rietveld (R). The "R" quality mark is used for patterns where it is clear that the d-­‐
values are directly the result of whole pattern fitting methods, such as the Rietveld
or decomposition methods. The entry should meet all the requirements of a Star (S).
• Indexed (I). Indicates the pattern has been indexed.
• Blank (B). Indicates the pattern does not meet the Star, Indexed, or Low-­‐Precision
criteria.
• Low-­‐Precision (O). Indicates the diffraction data have been taken on poorly
characterized material or that the data are known (or suspected) to be of low
precision.
• Calculated (C). Indicates the powder pattern was calculated from single-­‐crystal
structural parameters, for which the structural refinement R-­‐factor was < 0.10.
• Prototyping (P). Indicates the structural data that was assigned to a particular entry
from the Linus Pauling File. Prototype structure is an editorial action to assign a
space group and coordinates for entries that have not recovered this information
from the primary literature.

• Hypothetical (H). Indicates the structure is calculated theoretically from the atomic
positions and thermal parameters of an isostructural compound.
• Good (G). Indicates the non-­‐crystalline pattern has no unit cell, but does have
chemical analysis, characterization of local structure (either by pair distribution
function or spectroscopy) and a good signal-­‐to-­‐noise.
• Minimal Acceptable (M). Indicates the non-­‐crystalline pattern has a good signal-­‐to-­‐
noise and a desirable chemical analysis.
(Taken from Help files for PDF-­‐4+ 2012 software)