The crystal structure of the displacive ferroelectric mineral russellite, Bi2WO6, has been determined using Rietveld profile refinement of high-resolution, time of flight, neutron powder diffraction data on the synthetic compound. Russellite is orthorhombic, Pca21, with a 5.43726(2) Å, b 16.43018(5) Å, c 5.458422) Å, Z = 4 and is isostructural with the bismuth molybdate mineral koechlinite, Bi2MoO6. The structure consists of layers of tilted WO6 octahedra sandwiched between layers of bismuth

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... oxygen with the tungsten displaced from the centre of the octahedron by 0.278 Å. The orientations of the lone-pair electrons in the Bi3+ cations have been inferred from the 3.0 Å coordination shells of both crystallographically independent bismuths, and have been found to be non-centrosymmetric, an effect which may give rise to the tilting of the WO6 octahedra. New laboratory source X-ray powder diffraction data are presented for russellite, which, with supplementary synchrotron powder diffractometry, corroborate the new space group and structure determination.