Monte Carlo domain structure simulation and Debye equation calculation of XRD patterns were used to confirm the formation of domain structure and investigate its peculiarities. Correspondence of simulated XRD patterns with synchrotron powder diffraction experiments is achieved on the conditions that beside of 90o rotations of brownmillerite-like domains inside perovskite-like matrix each domain contains areas with perpendicularly oriented tetrahedral chains. Influence of such parameters as stoichiometry, average domain size, orthorhombic distortion degree on the XRD patterns is considered.
