Solid State Phenomena Vol. 130

Abstract: Elementary to sophisticated approaches allow for crystal structure prediction from empirical and theoretical principles since a few decades. Some recent efforts in inorganic chemistry for the production and classification of structure-candidates are described. The discussion is focused on an incredibly huge list of hypothetical zeolites, more modest series of aluminum fluoride polymorphs, or titanosilicates (etc) build up from the exploration of a special topological class, the N-connected 3D frameworks.

Abstract: The highly-collimated, intense X-rays produced by a synchrotron radiation source can be harnessed to build high-resolution powder diffraction instruments with a wide variety of applications. The general advantages of using synchrotron radiation for powder diffraction are discussed and illustrated with reference to the structural characterisation of crystalline materials, atomic PDF analysis, in-situ and high-throughput studies where the structure is evolving between successive scans, and the measurement of residual strain in engineering components.

Abstract: A multi-purpose pattern-fitting system, RIETAN-2000, has been extensively utilized to contribute to many structural studies. It offers a sophisticated structure-refinement technique of whole-pattern fitting based on the maximum-entropy method (MEM) in combination with a MEM analysis program PRIMA. We have recently completed a successor system, RIETAN-FP, to RIETAN-2000, adding new features such as standardization of crystal-structure data, an extended March-Dollase preferred-orientation function, and automation of imposing restraints on bond lengths and angles. Further, we have been developing a new three-dimensional visualization system, VESTA, using wxWidgets as a C++ application framework. VESTA excels in visualization, rendering, and manipulation of crystal structures and electron/nuclear densities determined by X-ray/ neutron diffraction and electronic-structure calculations. VESTA also enables us to display wave functions and electrostatic potentials calculated with part of these programs.

Abstract: The recent evolution of powder diffraction line profile analysis toward full pattern methods is discussed. Specific reference is made to the Whole Powder Pattern Modelling (WPPM), as applied to metals and ceramics subjected to strong plastic deformation. Examples concerning three different materials science studies are shown to illustrate features and potentialities of the WPPM approach.

Abstract: The main advantage of quasiperiodicity for the design of photonic and phononic crystals is the arbitrarily high rotational symmetry, which can be achieved without sacrificing a discrete Fourier (Bragg) spectrum. Consequently, the degree of isotropy can be arbitrarily increased leading to omnidirectional bandgaps. These are important for most applications as for instance wave-guides or -shields.