Acta Crystallographica Section B

Structural Science

Volume 56, Part 3 (June 2000)

research papers

Acta Cryst. (2000). B56, 426-430 [ doi:10.1107/S0108768100001166 ]

The tetragonal phase of Na_0.5Bi_0.5TiO₃ - a new variant of the perovskite structure

G. O. Jones and P. A. Thomas

Abstract: The structure of the tetragonal phase of the A-site-substituted perovskite sodium bismuth titanate, Na_0.5Bi_0.5TiO₃, has been determined by neutron powder diffraction at 698 K. The structure was refined in space group P4bm with a (= b) = 5.5191 (1), c = 3.9085 (1) Å, V = 119.055 (5) Å³, Z = 2 and D_x = 5.91 Mg m^-3. The structure exhibits an unusual combination of in-phase (a⁰a⁰c⁺) tilts and antiparallel cation displacements along the polar c axis, which results in a new variant of the perovskite structure.