Profile Data Acquisition for the JCPDS?ICDD Database

Abstract

The principal advantage offered by a fully digitised diffraction pattern is the retention of all features of the experimental pattern, including the line width and shape, the form and distribution of the background, etc. A file containing this type of reference data would in the future allow the use of techniques yet to be developed and of data processing, such as peak location, background subtraction and a2 stripping. The availability of digitised reference patterns would also allow the use of pattern-recognition techniques for qualitative phase analysis, as well as offering interesting possibilities for quantitative work. Until recently most commercially available automated powder diffractometers were limited to 10-20 Mbytes of disc storage and since a single fully digitised pattern requires about 10 kbytes, the provision of a file for thousands of digitised single phase reference patterns has not been possible. The recent advent of compact disc-read only memory (CD-ROM) systems providing in excess of 500 Mbytes now offers a low cost data storage capability. Plans are now in place for a new version of the Powder Diffraction File consisting of fully digitised patterns. Because of the need to maintain the database for years to come, it is most important that the stored data be as accurate and complete as possible.