Real-space refinement of single-crystal electron diffuse scattering and its application to Bi 2 Ru 2 O 7- δ

A real-space atomistic refinement approach to the analysis of experimental electron diffraction patterns is described. The method employs the reverse Monte Carlo algorithm to produce atomistic configurations capable of qualitatively reproducing diffuse electron scattering patterns. Its implementation in the program EDRMC is described in detail, together with a number of additional constraints/restraints that can be used to guide the refinement process. In particular, appropriate restraints ensure the individual atomic displacements introduced to model the diffuse scattering patterns are simultaneously consistent with the known average structure. The approach is then used to interpret electron diffraction patterns measured for Bi2Ru 2O7-δ. The diffuse scattering patterns observed are shown to arise primarily from concerted translations of Bi atoms. These translations can be interpreted in terms of rotations of [O ′Bi4 ] tetrahedra correlated along the crystal axes and uncorrelated along orthogonal directions

Structured diffuse scattering, local crystal chemistry and metal ion ordering in the (1 - x )MgS • x 3Yb 2 S 3 , 0≤ x ≤~0.45, 'defect' NaCl system

Rare earth sulfide solid solutions of 'defect' NaCl average structure type exhibit excellent colour characteristics and thus represent good prospects for use in the paints and plastics industry. As the colour characteristics of such systems are closely related to the local distribution of rare earth ions, it is important to know as much as possible about the latter. In this contribution, the reciprocal space shape of a highly structured, diffuse intensity distribution observed in a (1 -x)MgS xYb2/3S, x = 0.30, sample is used to show that the smallest polyhedral building blocks of the average NaCl structure type should each have, as far as possible, the same composition as the overall macroscopic composition. Local crystal chemical considerations suggest that both the Yb3+ ions and the vacancies would prefer to be opposite Mg2+ ions

A novel high-temperature commensurate superstructure in a natural bariopyrochlore: A structural study by means of a multiphase crystal structure refinement

Additional X-ray diffraction effects yielding an eightfold commensurate superstructure [a=20.974(5)Å] of the ideal pyrochlore structure were observed after annealing at 873 K of a thallium-doped bariopyrochlore single crystal. Electron diffraction indic

A composite modulated structure mechanism for Ag + fast ion conduction in pearceite and polybasite mineral solid electrolytes

A careful electron diffraction investigation of pearceite-Tac and polybasite-Tac samples in the Ag+ fast ion conducting state reveals that the average hexagonal [AgI9]9+ sub-structure in these mineral solid electrolyte systems is mutually incommensurabl

Synthesis, structures and phase transitions in the double perovskites Sr 2- x Ca x CrNbO 6

The synthesis and crystal structures of nine members of the rock-salt ordered double perovskites Sr2-xCaxCrNbO6 is presented. The crystal structures of the end members of the series Sr2CrNbO6 and Ca2CrNbO6 were refined using powder neutron diffraction data and are cubic in Fm over(3, -) m and monoclinic in P21/n, respectively, in both cases there being considerable anti-site Cr-Nb mixing. Variable temperature and/or composition studies suggest a direct first-order P21/n to Fm over(3, -) m transition, a suggestion supported by selected area electron diffraction studies. Crow