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Lider V.V.,RAS Shubnikov Institute of Crystallography
Physics-Uspekhi | Year: 2014

Various configurations of the X-ray crystal interferometer are reviewed. The interferometer applications considered include metrology, the measurement of fundamental physical constants, the study of weakly absorbing phase objects, time-resolved diagnostics, the determination of hard X-ray beam parameters, and the characterization of structural defects in the context of developing an X-ray Michelson interferometer. The three-crystal Laue interferometer (LLL-interferometer), its design, and the experimental opportunities it offers are given particular attention. ©2014 Uspekhi Fizicheskikh Nauk Russian Academy of Sciences. Source

Petukhov B.V.,RAS Shubnikov Institute of Crystallography
Journal of Experimental and Theoretical Physics | Year: 2012

The statistical Kolmogorov–Mehl–Johnson theory of solidification is generalized with allowance for the effect of obstacles creating delays for the propagation of new-phase boundaries, as applied to one-dimensional systems. An equation is derived to describe the process kinetics and is used to calculate the time dependence of the fraction of a transformed substance. The modification of the kinetics caused by changes in the obstacle density and the obstacle-induced delay time is studied. The theory can be applied to the extended contacts in large-scale integration circuits, biological macromolecules, and many other systems. © 2012 Pleiades Publishing, Inc. Source

Sobolev B.P.,RAS Shubnikov Institute of Crystallography
Crystallography Reports | Year: 2012

The manifestation of gross nonstoichiometry in MF m-RF n systems (m < n ≤ 4) has been studied. Fluorides of 34 elements, in the systems of which phases of practical interest are formed, are chosen. To search for new phases of complex composition, a program for studying the phase diagrams of the condensed state (~200 systems) has been carried out at the Institute of Crystallography, Russian Academy of Sciences. The main products of high-temperature interactions of the fluorides of elements with different valences (m n) are grossly nonstoichiometric phases of two structural types: fluorite (CaF 2) and tysonite (LaF 3). Systems of fluorides of 27 elements (M 1+ = Na, K; M 2+ = Ca, Sr, Ba, Cd, Pb; R 3+ = Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; R 4+ = Zr, Hf, Th, U) are selected; nonstoichiometric M 1 -xR xF m(1 -x) + nx phases, which are of greatest practical interest, are formed in these systems. The gross nonstoichiometry in inorganic fluorides is most pronounced in 80 MF 2 -RF 3 systems (M = Ca, Sr, Ba, Cd, Pb; R are rare earth elements). The problems related to the growth of single crystals of nonstoichiometric phases and basic fields of their application as new fluoride multicomponent materials, the properties of which are controlled by the defect structure, are considered. © 2012 Pleiades Publishing, Inc. Source

The current state of the art related with the selforganization of crystal-forming systems, where long-range order spontaneously appears in the arrangement of structural units of any nature (micro- and macromolecules or atomic clusters), is considered. Three partially overlapping stages of self-organization of a system accepted in physical models of "order-disorder" kinetic transitions are matched to those used in supramolecular chemistry. An algorithmically constructed model of transition from disordered to hierarchically ordered systems is considered. The geometrical and topological modeling of density fluctuations of n-atomic species (clusters) A n in a crystal-forming medium is carried out. Clusters A n of a higher level of the system self-organization (the time moment t i) were determined as assemblies of specially selected clusters at the lower level (the time moment t (i-1)). Such clusters are built of equivalent clusters and, therefore, have a hierarchical structure; i.e., the simplest clusters are integrated into the clusters of the next higher level. Also, the mechanism of self-assembly of symmetrically and topologically different chains and microlayers (in the form of planar nets) from cyclic clusters An is considered in the model system. The 45 obtained nets correspond to 11 uninodal Shubnikov nets and new binodal nets. Algorithms are presented for combinatorial and topological analysis to search for precursor clusters and restore a three-dimensional net of covalent and non-covalent bonds in a crystal structure by the matrix (cluster) self-assembly mechanism. The developed model is universal. The mechanism of self-assembly has been modeled for O 3 (ozone), C 6H 6 (benzene), C 2H 2 (acetylene), NaAlSi 3O 8 (albite), K 2.25Na 0.31Ca 2.25Ba 1.44 (Al 11.5Si 30.5O 84H 1.4) (H 2O) 25 (paulingite, PAU), B(OH) 3, H 3B 3O 6, H 2SeO 3, the Friauf-Laves structure family(which counts in 1,400 of binary and ternary compounds): MgCu 2 (cF24), MgZn 2 (hP12), and MgNi 2 (hP24), the icosahedral structures: B 12, C 20H 20, C 60, ZrZn 22 (cF184), and NaCd 2 (cF1192) Samson Phase. © Springer Science+Business Media, LLC 2012. Source

Kaminskii A.A.,RAS Shubnikov Institute of Crystallography
Doklady Physics | Year: 2013

The basic χ(3) nonlinear laser properties of tetragonal vanadates (YVO4, GdVO4, ErVO4, YbVO 4, LuVO4, Y0.5Gd0.5VO4, and Gd0.5Lu0.5VO4), which represent a novel class of SRS-active crystals, are presented. The presence of combined χ(3) active phonon modes in the GdVO4 crystal at a cryogenic temperature (∼9 K) is reported. © 2013 Pleiades Publishing, Ltd. Source

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