We present a detailed single crystal x-ray diffraction study of twinned orthorhombic perovskites. The diffraction pattern can be indexed on a 2apx2apx2ap lattice, but does not obey cubic symmetry relations. The data can be modelled in space group Pnma with a twin based on a distribution of the b axis over three perpendicular cubic axes. This model allows full structure determination in the presence of up to six twin fractions from single crystal x-ray diffraction data.
@article{arxiv.cond-mat/0103628,
title = {Twin model for orthorhombic perovskites},
author = {Bas B. Van Aken and Auke Meetsma and Thomas T. M. Palstra},
journal= {arXiv preprint arXiv:cond-mat/0103628},
year = {2007}
}