The ICDD's Powder Diffraction File™ (PDF®) is a database of inorganic and organic diffraction data used for phase identification and materials characterization by powder diffraction. The PDF has been available for over 75 years and finds application in X-ray, synchrotron, electron, and neutron diffraction analyses. With entries based on powder and single crystal data, the PDF is the only crystallographic database where every entry is editorially reviewed and marked with a quality mark that alerts the user to the reliability/quality of the submitted data. The editorial processes of ICDD's quality management system are unique in that they are ISO 9001:2015 certified. Initially offered as text on paper cards and books, the PDF evolved to a computer-readable database in the 1960s and today is both computer and web accessible. With data mining and phase identification software available in PDF products, and the databases’ compatibility with vendor (third party) software, the 1 000 000+ published PDF entries serve a wide range of disciplines covering academic, industrial, and government laboratories. Details describing the content of database entries are presented to enhance the use of the PDF.

Advances in instrumentation, software applications, and database content have all contributed to improvements in pharmaceutical analyses by powder diffraction methods in the 21stcentury. When compared to the globally harmonized United States Pharmacopeia General Chapter <941>, “Characterization of Crystalline and Partially Crystalline Solids by X-ray Powder Diffraction”, many historic problems in pharmaceutical analysis have been addressed by combinations of improved methods and instrumentation. Major changes in the last 20 years include (i) a dramatic lowering in detection capability and detection limits, (ii) enhanced capabilities for dynamic measurements such asin situanalyses under a variety of conditions, and (iii) the ability to identify and characterize nanomaterials, non-crystalline, and amorphous materials by both coherent and incoherent scattering profiles.

A total pattern analysis suite of programs has been developed and incorporated into the ICDD® PDF-4 database. While the suite of programs is intended for the analysis of any diffraction pattern, particular attention was focused on the analysis of common amorphous, non-crystalline, or partially crystalline materials found in minerals, polymers, and pharmaceuticals. The suite of programs directly interfaces to the ICDD database and libraries of non-crystalline references.

The crystal structure of a new polymorph of germacrone has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. This polymorph (Form II) crystallizes in space group C2/c (#15) with a = 26.0073(4), b = 9.84383(10), c = 10.53713(13) Å, β = 95.7547(11)°, V = 2684.04(3) Å3, and Z = 8. The crystal structure is dominated by van der Waals interactions, but four C–H⋯O hydrogen bonds are present. The structure exhibits many similarities to the previously reported Form I polymorph FIQLOG, but is clearly different. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF).

A collection of 65 formulated tablets and capsules were analyzed for phase composition by full pattern matching powder diffraction methods. The collection contained 32 of the top 200 prescription drugs sold in 2016 as well as many high-volume prescriptions and over the counter drugs from prior years. The study was used to evaluate new methods of analysis as well as the efficacy of programs designed to collect references on high volume excipients and pharmaceuticals for inclusion in the Powder Diffraction File™. The use of full pattern matching methods as well as reference pattern additions of many common excipients enabled major phase excipient identification in all formulations. This included identification of crystalline, nanocrystalline, and amorphous ingredients because full pattern matching involved the use of characteristic coherent and incoherent scatter. Oftentimes identification of the major excipients significantly aided the clean identification of the active pharmaceutical ingredients (APIs) and their polymorphic form, even at low concentrations (1–10 wt. %). Overall 93% of the APIs were identified, most through a PDF®material reference, but also through patent cross-referencing and similarity analysis comparisons.