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The superspace concept is a new crystallographic approach for the generalisation of symmetry, structural models and structure dependent properties. Although the original motivation for the superspace was intended to describe symmetry of aperiodic crystals, ...
After studying more than 100 different samples of calaverite Au1-pAgpTe2 (p 2CO3 resisted any attempt for a precise structural analysis. The appearance of satellite reflections was noted on single crystal diffractograms which led to the generalisation of t ...
The structure of aperiodic crystals which includes incommensurate, quasi- and composite crystals is usually described in spaces of higher dimension, the so called superspace. The main advantage of the superspace formalism is that an aperiodic structure in ...
The room temperature structure (a-form) of the organic compound p-chlorobenzamide, C7H6ClNO, can be described as a classical three-dimensional periodic superstructure (alpha(s)) and also as a commensurately modulated structure (alpha(m)) in (3 + 1)-dimensi ...
The high- and low-temperature forms, i.e., phase I (stable above 328 K) and phase II (stable below 328 K), of Cu8GeSe6 have been investigated by the powder X-ray diffraction method. Cu8GeSe6 II is hexagonal with A = 12.6438(2), C = 11.7570(1) Angstrom, Z = ...
Pb2CoWO6 in its incommensurate phase (230 less than or equal to T less than or equal to 300 K) invariably exhibits orientational domains. Such a polydomain state has been investigated by means of X-ray diffraction at 283 K. Assuming the modulation to be on ...
Molecular-geometry calculations in the superspace framework of incommensurate structure analysis are presented in detail. In particular, a method is described for attaching atoms to groups of others without the necessity of introducing further modulation f ...
The structure of a crystal of natural melilite from San Venanzo, Umbria (Italy) of the general formula X(2)T1(T2)(2)O-7, where X = Ca0.945Sr0.005Na0.04K0.01, T1 = Mg0.92Al0.08 and T2 = Si0.99Al0.01, has been solved and refined as an incommensurate structur ...
