History of the ICDD

After the development of the first X-ray powder diffraction techniques in the early part of the twentieth century, the need for a central collection of diffraction patterns from known phases became apparent. Following the publication of two landmark papers in the late 1930s on the archiving and use of powder data for phase analysis by Dow scientists, the Joint Committee for Chemical Analysis by Powder Diffraction Methods was founded in 1941. They produced a primary reference of X-ray powder diffraction data, which became known as the Powder Diffraction FileTM (PDF). This effort was initially supported by Committee E-4 of the American Society for Testing and Materials (ASTM). Over the next two decades, other professional bodies added their support, culminating in 1969 with the establishment of the Joint Committee on Powder Diffraction Standards (JCPDS). The JCPDS was incorporated to continue the mission of maintaining the PDF. In 1978, the name of the organization was changed to the International Centre for Diffraction Data (ICDD) in order to highlight the global commitment of this scientific endeavor.

The ICDD Organization

Membership consists of scientists from various affiliations – educational, governmental, and industrial. Approximately 300 scientists from around the world comprise the active membership from which the organization draws its Board of Directors, committees, and subcommittees. The members, who are volunteers, are actively engaged in developments in the field of X-ray powder diffraction and related disciplines. Annual meetings of the members provide a forum for the exchange of ideas and information pertinent to the scientific community and to organize, plan, and review policies and procedures within the ICDD organization. A paid scientific and administrative staff, located at the Newtown Square, Pennsylvania Headquarters, is responsible for the production and distribution of the various databases offered by the ICDD.

The Powder Diffraction FileTM

The Powder Diffraction FileTM (PDF®) is a collection of single-phase X-ray powder diffraction patterns in the form of tables of characteristic interplanar spacings and corresponding relative intensities along with other pertinent physical and crystallographic properties. The creation, maintenance, and dissemination of such a file was the primary purpose for the establishment of the ICDD and its predecessor organizations. Annual supplements to the File contain approximately two thousand patterns each.

In order to meet the individual need of diffractionists worldwide, the Powder Diffraction File™ is available in various formats. The PDF has various subfiles of data which include, but are not limited to, minerals, metals and alloys, and forensic materials. There is also an educational package for classroom use. Various methods, including the use of printed indexes and computer software, enable users to match data in the File with their laboratory data.

Data Acquisition for the PDFTM

Data for the publication in the Powder Diffraction FileTM are acquired through contributions from individual scientists, corporate laboratories, literature surveys, and a Grant-in-Aid program. Approximately 200 leading scientific journals are searched manually for powder diffraction data. Additional literature surveys covering patents, dissertations, and the remaining open literature are performed utilizing various online databases and search techniques.

PDF Quality Assessment

All data are critically reviewed and evaluated by the editorial staff. Each pattern must pass through a four-tiered editorial review process before it can be included in the PDF. As technology evolves, the quality requirements for reference pattern data also evolve. As a result, information in the PDF is continuously reviewed and upgraded for accuracy and quality.

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