Superstructure Determination of PbZrO₃

By taking into account the effects of domain structures and X-ray absorption, the superstructure of PbZrO₃, lead zirconate, has been determined at room temperature. The space group is Pbam with a unit cell of a = 5.8884 (19), b = 11.771 (4) and c = 8.226 (3) Å, with Z = 8. The intensity data were collected using short-wavelength synchrotron X-rays of 0.350 Å; this reduces the linear absorption coefficient to 11.93 mm^-1. The structure refinement was performed using only the data of superlattice reflections which are free from ambiguity and resulting from the domain structure; the final R value is 0.047 for 335 unique superlattice reflections. Zr atoms show the antiphase-type displacement along the z axis; oxygen octahedra show tilt of the type a^-a^-c⁰ using Glazer's [Acta Cryst. (1972), B28, 3384-3392; Acta Cryst. (1975), A31, 756-762] notation.

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