LCBASE: Program and database for phase identification

Abstract

A computer program for phase identification using powder diffraction data is presented. It works with a small database containing the unit-cell dimensions and Bravais lattice for chosen classes of inorganic substances. The algorithm works for single phase samples and such samples in which a single phase dominates. During the search, the peak positions generated using the reference unit cells are compared with the experimental ones. Unit-cell constants of all obtained solutions are (optionally) immediately refined. Application examples show that the method gives as possible solutions those database entries for which the cell dimensions differ from the investigated sample by not more than about 0.05 Å. These entries may include the true phase or isotypical phases unless the imposed chemical constraint does not exclude them. If the sample is a solid solution, then the algorithm is able to find phases of differing chemical composition belonging to the same solubility range (provided that the difference in lattice constants is not too large). One of the examples illustrates the possibility of application for electron-diffraction data.