Databases

A database, which allows an electronic evaluation of diffraction diagrams, is required to identify the appropriate phases. The base is the cataloging of the d and θ 2 values ​​with the corresponding relative (ie normalized to the strongest peak) intensities. Further information on the lattice parameters and crystal structure of that element or compound in question, the measurement conditions (type of radiation, filters, detectors), as well as physical properties and information about the source of data necessary. 

Begun in 1938 by Hanawalt a collection of d/I data sets (Powder Diffraction File, PDF File) was the basis for the still valid phase identification system. It is today managed and further developed by the International Centre for diffraction data ICDD (formerly Joint Committee of on powder diffraction standards JCPDS) in the United States. Licenses of this database are provided for a fee to interested users. 

In addition, a number of databases with X-ray diffraction data, who usually cover only a specialty, evolved in recent years on the Internet.  These databases are usually available free of charge.