The crystalline structures of the superionic high-temperature copper selenides Cu(2-x)Se (0 < x < 0.25) produced using mechanical alloying were investigated using X-ray diffraction (XRD). The measured XRD patterns showed the presence of peaks corresponding to the crystalline superionic high-temperature alpha-Cu(2)Se phase in the as-milled sample, and its structural data were determined by means...

— The crystal structure of K2TiSi3O9•H2O has been solved ab initio from X-ray powder data. The unit cell is orthorhombic (space group P212121, Z = 4) with cell dimensions a = 7.1362(2) Å, b = 9.9084(3) Å, c = 12.9414(4) Å, V = 915.07 Å. The structural model was obtained from direct methods using 455 integrated intensities. The Rietveld refinement converged to final Bragg and profile indicators ...

Symmetry modes provide an alternative method to describe crystal structures. Using the fact that many crystal structures can be described as a distorted version of a higher symmetric parent structure, the traditional atomic positions, occupancies or lattice parameters are no longer used. Instead, all structural features are described applying symmetry modes. This can be of particular interest i...

Department of Physics, Shanghai University, Shanghai 200444, People’s Republic of China, Shanghai Key Laboratory of High-Temperature Superconductors, Shanghai 200444, People’s Republic of China, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s...

— α-NaCaAlF6 is prepared by solid state reaction as poor quality crystals. The structure is determined ab initio from conventional X-ray powder data. The cell is monoclinic, space group P21/c, Z = 8, with a = 8.7423(3) Å, b = 5.1927(2) Å, c = 20.3514(9) Å and β = 91.499(2)°. The final Rietveld refinement leads to RP = 10.6 % and RB = 5.2 %. The structure is built up from isolated AlF6 octahedra...