(also see PDF-2, PDF-4, and PDF-4 Support Software)

ICDD’s Mission
To be the world center for quality diffraction data, meeting the needs of the technical community.

To promote the application of materials characterization methods in science and technology, by providing a forum for the exchange of ideas and information and through publication of X-ray diffraction data.

The PDF Databases

Release 2008 of the Powder Diffraction File contains 622,117 unique material data sets. Each data set contains diffraction, crystallographic and bibliographic data, as well as experimental, instrument and sampling conditions and select physical properties in a common standardized format. The PDF’s large size and comprehensive material coverage is achieved through ICDD’s historical sources of powder diffraction data, ICDD’s Grant-in-Aid Program, contributions, and bibliographic searches, as well as collaborations with international crystallographic database organizations

The database is designed and produced in several different formats in order to serve different groups of users.

PDF-2 is a collaborative product between ICDD, FIZ and NIST and is designed for inorganic materials analyses. Many common organic materials from the ICDD are added to this database to facilitate rapid material identification. (purchase)

PDF-4+ is an advanced database containing the data from both the PDF-2 and ICDD’s collaboration with MPDS. This database has comprehensive material coverage for inorganic materials and it contains numerous features such as digitized patterns, molecular graphics and atomic parameters. Many new features have been incorporated into PDF-4+ to enhance the ability to do quantitative analysis by any of three methods: Rietveld Analysis, Reference Intensity Ratio (RIR) method or Total Pattern Analysis. (purchase)

PDF-4/Minerals is a subset of PDF-4+, which includes the new features incorporated into PDF-4+. (purchase)

PDF-4/Organics is a collaborative product between the ICDD and CCDC. It is designed to identify organic and organometallic materials and it contains a few thousand inorganic materials, primarily pharmaceutical excipients to help with formulation analyses and identification. (purchase)

WebPDF-4+ provides portability of the PDF-4+ database via the Internet. It enables access to the entire suite of programs and data files, so that it is equivalent to PDF-4+ 2008. (purchase)

Printed Books and Indexes include ICDD’s experimentally collected diffraction patterns and search manuals. These materials have been produced annually for 57 years and are commonly used as reference books. (purchase)

Compare PDF-4+ 2008 using DDView+ with PDF-2 Release 2008 using DDView

The Powder Diffraction File

• Comprehensive
• Continuous Quality Analysis and Improvement
• Designed for Material Identification
• Data Mining

Comprehensive

The Powder Diffraction File (PDF) combines data from multiple database sources to ensure comprehensive coverage of solid state materials. Materials data from around the globe are critically evaluated, categorized, and standardized to maximize your ability to identify and characterize materials. The ICDD is now entering its 58th year of annual publication. The database currently represents the collective works of hundreds of thousands of authors, thousands of publications, and 622,117 published material data sets.

The growth of the PDF is due to the contributions of several database organizations. These organizations extract and edit data from global sources on a continuous basis.

Collaborative partners include:

• Cambridge Crystallographic Data Centre (CCDC), Cambridge, UK—Cambridge Structural Database (CSD)
• Fachinformationszentrum Karlsruhe (FIZ), Karlsruhe, Germany—Inorganic Crystal Structure Database (ICSD)
• National Institute of Standards and Technology (NIST), Gaithersburg, Maryland
• Material Phases Data System (MPDS), Vitznau, Switzerland—Linus Pauling File (LPF)

In total, the ICDD receives and processes approximately 50,000 material data sets annually. After the ICDD editorial review, which includes quality analysis, standardization, duplicate removal and material classification, approximately 90% of the data sets are published. In Release 2008, a total of 45,437 new entries were published in PDF databases.

The steady increase in entries and comprehensive coverage is also indicated by the increase in unique author citations. The above figure shows the number of authors contributing to each database for the last five years.

Continuous Quality Analysis and Improvement

Do you appreciate quality as much as we do? Our quality is “built-in” the Powder Diffraction File. The ICDD editorial staff standardizes the data and reviews data quality from each data source and database collaborator. All the data in each PDF product are reviewed annually by a series of automated quality analysis programs, followed by an editor review.

The results, shown above, demonstrate the continuous improvement in published data quality over time. This improvement is attributed to improvements in both the hardware and software used for diffraction analysis, as well as the development of diffraction standards and standard calibration methods. However, as shown below, there is still an abundance of low quality data in recently published global literature. Although the data shown is for PDF-4+, the trends are similar for all databases.

A primary function of the ICDD editorial effort is to analyze the quality of each data set, analyze the rootcauses of any quality issues, and provide the analysis results to the user in the form of quality marks and specific comments in each entry’s comment section. In many cases, a low quality data set may be the only published data for a particular compound. In cases where it is not the only published data, ICDD editors provide cross-references and links to related entries.

Designed for Material Identification

Comprehensive material coverage, combined with quality review, facilitates material identification. This is because the majority of commercial search/match programs are designed to identify a material, perform a residual analysis between the reference and experimental data, and then perform successive identifications. Improper calculation of the residual pattern, due to a poor quality or incorrect reference material, can result in failure.

Cross-references can be used to direct the user to the best quality data and/or the primary reference. Crossreferences and quality marks can be used to identify the most appropriate data sets for quantitation by Rietveld Refinement or I/Ic values for quantitation by the Reference Intensity Ratio (RIR) method.

The database contains several methods for analyzing materials by prototype classification. Such classifications include Pearson Symbols, LPF Prototype, ICDD Prototype, ANX formulation, Mineral and Zeolite classifications. PDF databases are designed as relational databases, with JAVA™ interfaces, to help the user apply any or all of these classification systems in any combination.

Complimentary analytical data can also be used with the database through searches such as the elemental composition search (XRF, SEM), functional group search (IR, NMR, MS), density, color, and melting point searches.

Data Mining

In addition to diffraction data, PDF entries contain bibliographic, crystallographic, and physical property data, as well as a series of subfile and structural classification systems. Overall, this results in >100 different data fields for each PDF entry. Any of these fields can be used to help users research and analyze materials problems.

PDF databases are housed in a relational database format (Sybase® 10), with JAVA™ interfaces to facilitate data mining. Our most advanced databases, represented by the PDF-4 product line, have the ability to perform 48 different searches and display 70 different fields using our integrated DDView+ software. The PDF-2 product, coupled with our optional DDView software, has the ability to perform 46 searches and display 8 fields. New and powerful ways of analyzing data can be achieved by combining the searches and field displays. Statistical analysis and graphic packages were added last year to Release 2007, so that results can be analyzed and displayed.

Many applications for data mining can be found in the tutorial section of the ICDD web site. In addition to the tutorial on data mining, examples are also given in the electron diffraction, polymorph identification, XRF and SEM analyses tutorials.

ICDD web site: www.icdd.com/resources/tutorials/