PDF-4 Products
PDF-4+ Flyer (PDF)
PDF-4+ Scholar Flyer (PDF)
PDF-4+, an Electron Diffraction Database Flyer (PDF)
PDF-4+ - Purchase PDF-4+
PDF-4
Confidence comes with great results
More Data • More Data Mining
More Atomic Coordinates
More Types of Data
The PDF-4 family of databases is designed to provide users with continuously updated data from global resources. For several years, the ICDD has been processing over 50,000 new material data sets every year. These are sourced from international database organizations, private contributions, donations, grants and bibliographic literature (see Table 1).
The PDF-4 family of databases is designed to provide flexibility. This flexibility is demonstrated in our data mining, search, and graphics capabilities, as well as our display fields. Reference data can be represented as X-ray, neutron, synchrotron, or electron diffraction. Data can be viewed and displayed as traditional diffraction patterns (2 theta versus intensity) or two-dimensional plots (xy versus intensity), as either spot patterns or ring patterns, or as electron diffraction back scattered patterns (Kikuchi plots). Our plotting graphics are interactive, allowing the users to vary wavelength and various instrumental factors. There is also a selection of diffraction profiles, and crystallite size can be computed; the latter being important in the simulation of nanomaterial patterns. Our expanded list of select features and capabilities can be found here.
Table 1: Powder Diffraction Data Entry Source.
PDF-4+ 2010 - Purchase PDF-4+ 2010
Identify and Quantitate
301,282 material data sets
53 searches and 90 display fields
Highlights
- Comprehensive in materials breadth
- Data sourced from over 2,300 journals and 110,000 authors
- Extensive cross-referencing, prototyping and classification
- New for 2010 - 22,064 additional materials with atomic coordinates
- Digital patterns for noncrystalline, semicrystalline and amorphous materials
The PDF-4+ is designed to be comprehensive in the ability to identify and quantitate solid-state materials. This includes common, but noncrystalline solid-state materials, such as many polymers, clays and amorphous materials. These materials are difficult to characterize, hence ICDD uses targeted grants and known field experts to collect, review and edit reference data for the PDF.
Identify
PDF-4+ is sourced from four different crystallographic databases (see Figure 5). These databases all have separate editing systems, classifications and some unique sources of data which are combined in PDF-4+. Exact duplicates, from identical references are eliminated, which accounts for the varying entry populations when compared to data sourced for PDF-2. This results in the world’s most comprehensive inorganic materials database in terms of entries, number of journal sources, authors and materials with unique empirical formula. Data are constantly being added, standardized, edited and reviewed.
Figure 5. PDF-4+ data sources.
The diversity of materials in the database is demonstrated by the increases in all types of data. Figure 6 shows the distribution in compounds with one through five elements in PDF-4+ products since 2005. Note that all categories increased in size. Similar plots could be shown for subfile populations, number of empirical formula and various physical property data added to the database.
Figure 6. Compound distribution with one through five elements in PDF-4+.
Quantitate
With 301,282 standardized material data sets, the addition of noncrystalline materials, along with common organics and polymers make PDF-4+ a more powerful database for material identification.
The database also provides the critical information required for subsequent quantitative analysis. The most frequently used method by ICDD customers is Rietveld refinement, which requires atomic parameters including atomic coordinates; both of which are available in PDF-4+.
Figure 7. Increase in data entries with atomic coordinates.
As shown in Figure 7, the PDF-4+ database has been adding atomic coordinates to data sets at an ever-increasing rate. The ICDD has developed editorial review and analysis programs that automatically identify analogous material data sets without atomic coordinates of the same chemistry, diffraction pattern and unit cell parameters. ICDD then cross-references these data sets to materials with atomic coordinates. In total, over 60% of all entries (188,911 data sets) have either atomic coordinates or are cross-referenced to materials with atomic coordinates. The requirements in chemistry and crystallography are very strict for the cross-referencing since it is specifically designed to assist in automated or semi-automated Rietveld refinement. Also, every year with the addition of thousands of new data sets, the cross-referencing programs are rerun and the database continuously updated. For data sets with atomic coordinates, there is an array of molecular graphic options, integrated bond length and angle tables, as well as, nearest neighbor atomic environment displays and bond distances.
Figure 8. PDF-4+ also provides key data required for other quantitative analysis techniques such
as digital patterns for all entries (pattern fitting), indexed digital patterns (LeBail Method), and
reference intensity ratios for the RIR method.
