DETERMINATION OF CRYSTAL-STRUCTURE OF PEROVSKITES WITH SPACE GROUP-I4-MCM

A method is proposed for determining volume ratios of domains in a polydomain specimen of perovskite crystals with the space group I4/mcm; the ratios are fundamental parameters in determining the crystal structure. The method is based on measuring relative intensities of triplets of Bragg reflexions with special indices and is applied to structure determinations of SrTiO3 and KMnF3. A discussion is given of refinement of the structure; a difficulty in a least squares calculation owing to a correlation between structural parameters is emphasized. The use of accurate lattice-constant data together with a conventional structure analysis is recommended. © 1978, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.