Crystallography in Russia

Shubnikov Institute of Crystallography, Russian Academy of Sciences: 1940-2000

Foundation of the Institute

Aleksei Vasil'evich Shubnikov is justly considered one of the founders of the science on growth, structure, and properties of crystals. He initiated the physical direction in crystallography, broadened its horizons from the study of crystals within the framework of traditional mineralogy to the interdisciplinary science including physics, chemistry and mathematics. In 1934 Shubnikov organized the Crystallographic Section at the Lomonosov Institute of Geochemistry, Mineralogy, and Petrography in Moscow. In 1937, the crystallographic section was reorganized into the independent Laboratory of Crystallography of the USSR Academy of Sciences within the Dept. of Geological-Geographical Sciences. In November 1943 the Laboratory became the Institute of Crystallography in the Dept. of Physical-Mathematical Sciences of the USSR Academy of Sciences. A.V. Shubnikov was the first Director, Boris K. Vainshtein was the head of the Institute from 1962 to 1996, and Mikhail V. Kovalchuk has been the Director since 1998.

Development of scientific directions

The Institute of Crystallography was actively engaged in the fields of crystal symmetry and morphology, X-ray diffraction analysis, crystal growth and the synthesis of quartz. In 1939, N.N. Sheftal suggested a method for growing large crystals of Rochelle salt and high-quality piezoelectrics necessary for constructing sensitive piezoelectric devices for use in the war. In the 1940s, Shubnikov put forward a concept of antisymmetry for studying magnetic properties of crystals and N.V. Belov composed a theory of close packings and performed detailed X-ray diffraction analysis of the atomic structures of silicate minerals. In 1945, G.G. Lemmlein found a spiral relief in crystal faces associated with the helicoidal structure of the crystal lattice. Methods for studying crystal structure were being rapidly developed at the Institute. Vainshtein used Fourier synthesis to calculate the distribution of electrostatic potentials in crystal lattices based on experimental electron diffraction data (1949). Vainshtein and Z.G. Pinsker determined the structure of paraffin, and the localized hydrogen atoms within it. In the 1950s, S.A. Semiletov and coworkers obtained fundamental results on the mechanism of homoepitaxial growth of thin germanium films. At the same time S.K. Popov designed an automated industrial apparatus for growing ruby rods. In 1940s-1950s, N.V. Belov and his coworkers initiated studies on the crystal chemistry of silicates related to geochemical and geophysical processes and the production of cements, glasses, and ceramics. Their studies were used to develop low-temperature cement and new types of concrete. In 1951, Shubnikov published Symmetry and Antisymmetry of Finite Figures, in which he discussed the notion of four-dimensional crystallography.

Sheftal and coworkers synthesized dislocation-free germanium single crystals and put forward the concept of artificial epitaxy for obtaining oriented films on amorphous substrates. In 1969, the scientists of the Institute grew oriented systems of whiskers on single-crystal substrates, a method useful for the production of semiconductors. V.L. Indenbom found (1958) that the structural transformation observed in Rochelle salt is a second-order phase transition. Scientists at the Institute, headed by I.S. Zheludev and L.A.Shuvalov, worked on the general laws of formation of structures possessing spontaneous polarization and found new ferroelectric materials.

B.N. Grechushnikov, in cooperation with G.I. Distler, worked on the theory of Fourier-spectroscopy and designed and constructed a Fourier spectrometer. This instrument obtained well-resolved illumination light spectra from the Saturn disk and rings.

In 1962, the group, headed by Kh.S. Bagdasarov, built a stably operating laser. In 1972, laser radiation from chromium ions in garnets was achieved. At the beginning of the 1960s, the scientists of the Institute determined the structures of synthetic analogues of a protein (a complex polypeptide), crystallized enzymes into tubes with monomolecular walls, and determined the structure of leghemoglobin. In the 1980s, the scientists of the Institute developed an experimental approach to high-pressure studies of crystals using diamond anvils, increasing the range of attainable pressures (up to 100 GPa) and broadening the spectrum of problems solvable by this method.

Fundamental studies in the theory of dislocations, the physics of plasticity, the theory of phase transitions in crystals, and the theory of symmetry were pursued. In particular, the existence of improper phase transitions was predicted. The studies of the statistical kinetics of spiral-layer crystallization helped to clarify many processes. In 1990s the scientists of the Institute developed the theory of electrooptical and ferroelectric properties of liquid crystals and designed many applicable devices.

Development of technology of crystal synthesis

L.M. Belyaev and his coworkers studied the synthesis of organic and inorganic crystal-scintillators with high scintillation efficiency. In the 1960s, A.A. Shternberg worked out the industrial synthesis of a rock crystal, piezoelectric quartz.

A method for horizontal crystallization for growing refractory single crystals was developed along with the technologies for growing large almost perfect single crystals of yttrium-aluminum garnet, sapphire, and yttrium aluminate. Industrial facilities for growing single crystals were constructed.

Methods of the thermal-compression junction and creation of solid-phase junctions of laser crystals that guarantee high optical quality of the interfaces were developed. New crystallization apparatus for growing crystals in space were also constructed, and crystallization experiments were performed on water-soluble crystals under the conditions of microgravity at the Salyut-5 orbital station (1976).

Instrument design

A series of specialized diffractometers have been designed at the Institute including the TRS triple-crystal X-ray diffractometer, the KARD-4 automated coordinate X-ray diffractometer, the RED-EL four-circle X-ray diffractometer, the DAR family of automated X-ray diffractometers, and the AMUR series of X-ray small-angle diffractometers. An automated 512-channel diffractometer for proteins was also constructed. In cooperation with the Laboratory of High Energies of the Joint Institute for Nuclear Research (JINR) in Dubna, a two-dimensional proportional chamber for the automated KARD diffractometer for studying protein single crystals was designed. Methods for studying polycrystalline materials, polymers and liquid crystals in X-ray diffractometers with two-dimensional detectors were also developed.

The Institute of Crystallography in the 21st century

New scientific priorities

At present, the Shubnikov Institute is focusing on the following problems:

• Creation of new crystals, films, and structures with specific properties;
• The study of the structures and properties of condensed matter using X-ray and synchrotron radiation, neutrons, and electrons;
• Further development of existing instruments and methods and creation of new ones;
• Study of properties of biological materials and organic systems;
• Study of condensed matter under microgravity;
• Study of surfaces, subsurface layers, interfaces, thin films, and track membranes;
• Development of X-ray optics; and
• Design and construction of apparatus for crystal growth.
  

The Institute also participates in the following projects of the Federal Scientific and Technological Program:

• Physics of Radiation,
• Condensed Matter,
• High-Precision Measurements,
• Quantum and Nonlinear Processes,
• Physics of Solid Nanostructures,
• Information Technologies and Electronics,
• New Materials and Chemical Products,
• Scientific Instrument Engineering.
  

Within the framework of the Russian Academy of Sciences, the Institute performs work on laser systems, strongly correlated electrons, nanomaterials and nanotechnologies. The Institute of Crystallography participates in the Federal Space Program of Russia.

Shubnikov participated in the organization of the lUCr and suggested the title Acta Crystallographica for its printed edition. Belov served as the IUCr President from 1966 to 1969, Vainshtein and V.I. Simonov were Vice-Presidents in 1975-1978 and 1984-1987, respectively. The Institute of Crystallography cooperates with more than twenty foreign scientific organizations participating in numerous interacademic and interinstitute agreements. The Institute holds annual Shubnikov, Vainshtein, and Belov lectures.

Structural studies

Kovalchuk and his laboratory developed different surface-sensitive and phase-sensitive X-Ray diffraction methods, among them - new modification of X-ray Standing Waves (XRSW) with photoelectrons. This method combines high resolution X-ray diffraction and spectroscopy. The XRSW method has been modified for the structural characterization of multicomponent crystals, semiconductor heterostructures, multilayer X-ray mirrors, X-ray waveguide structures, organic multilayer systems based on Langmuir-Blodgett films, and protein-lipid systems on solid and liquid substrates. Coherent interaction of X-ray and synchrotron radiations with condensed matter in the range of hard wavelengths have been studied. XRSWs with periods varying from 0.001 to 100 nm based on the phenomena of double- and multibeam diffraction, total external reflection, etc. have been developed.

M.V. Kovalchuk and S.I. Zheludeva used fluorescence in the range of total external reflection of X-rays for localization of ions inside organic multilayers. The study of protein-lipid systems on liquid surfaces and solid substrates revealed the effect of drugs on heavy atom positions. Today scientists at the Institute actively use synchrotron radiation in many fields of modern crystallography and they play a leading role in researches at Kurchatov Center of Synchrotron Radiation (KCSR).

Studies of the semiconductor In_x Ga_1-x As/GaAs demonstrated the value of X-ray diffraction in characterization of multilayer systems including determination of the thickness and compositions of individual layers, interface structures, and defects in the layers. Computer simulation of the growth of icosahedral quasicrystals has been performed. New types of diffraction reflections in crystals of germanium and a germanium-silicon alloy have been predicted. Defects arise because of distortion of the electronic state of germanium atoms by thermal vibrations and point defects. Such reflections have been observed in technologically important crystals and alloys. The group, headed by N.A. Kiselev, used high-resolution electron microscopy to study nanotubes with multilayer cylindrical walls and walls consisting of conic graphene layers and surface-modulated walls. L.A.Feigin's laboratory had a large contribution in the development of small angle scattering methods (theory, experiments and instrumentations) in application of X-R reflectometry in the study of different bioorganic materials.

Shortly before the 60th Jubilee of the Institute, a newly discovered mineral was officially named IKRANITE by the International Mineralogical Assn. Five other minerals have been named after scientists of the Institute: shubnikovite, belovite, lemmleinite, stishovite, and rastsvetaevite. The Institute regularly holds national conferences on crystal growth and annual schools on electron microscopy.

New crystalline media

Using hydro-thermal methods, nanocrystalline ZnO powders were obtained with luminescence characteristics significantly exceeding those of powders obtained by traditional methods (L. Demianetz group). The sol-gel synthesis in nonaqueous media produced cathode materials for lithium batteries. A method of diamond deposition onto silicon tips has been developed to enhance the autoemission of silicon cathodes. Systems of whiskers are used as the tips for autoemission cathodes. Single-crystal silicon wires with a diameter of 5 nm have been obtained, which are promising for potential nanoemitters.

A Gd-containing fast scintillator has been suggested in the fluoride family (together with the Russian Research Center Kurchatov Institute). Such a scintillator is very promising for recording low-energy neutrinos. Langasites, a new family of highly efficient piezoelectrics, has been discovered by Pisarevsky's group in cooperation with Moscow State University.

Bioorganic materials science

The three-dimensional structure of a Ricinus communis Agglutinin was determined at a resolution of 2.5 Å using synchrotron radiation. The proteins of this group are used as stimulators of the immune system. The Institute developed a method and apparatus for protein crystallization that can also be used for growth of biocrystal films under the conditions of microgravitation. The Institute has developed a method for interactive modeling of structures of bio-polymer molecules in solution based on data from small-angle X-ray and neutron scattering. This allows one to determine not only the shape but also the inner structure of the particles, to analyze the domain structure and the dynamics of macromolecules in solution, and to reconstruct the structure of protein molecules in solution. Software designed at the Institute is used in many laboratories around the world.

Scientific engineering

Numerous instruments have been developed by Kovalchuk and co-workers for use on the synchrotron facilities at the Kurchatov Synchrotron Radiation Center including the experimental station for medical diagnostics (Mediana), protein crystallography (Belok), precision X-ray optics (PRO), material science (RKFM) and EXAFS station. Instruments for robotic growth of large (75 mm diameter) high quality single crystals have been perfected. Of particular note are crystals of sapphire-titanium (Al₂O₃:Ti³⁺) used in a new generation of terawatt lasers in the femtosecond range

Studies of physical properties

The effect of high pressures on the structural, magnetic, transport, and optical properties of magnetic materials is studied in high-pressure chambers with diamond anvils. Magnetic-nonmagnetic and dielectric-metal phase transitions, ferroelectric properties of ultrathin Langmuir-Blodgett polar films, and polarization switching in films of a P(VDF-TrFE) copolymer have been explored.

Active lithium niobate (a nonlinear optical material) was found to have impurities (Mg, Zn, In, etc.). By varying the doping level, it is possible to vary these properties. Magnetically stimulated strengthening of crystals manifests itself as a decrease in the dislocation mobility under the joint action of an applied mechanical load and a magnetic field. Atomic force microscopy (AFM) was found to be an efficient way to study the domain structure of polar surfaces of ferroelectrics. Analysis of the data revealed the effect of crystal-lattice distortions on dislocation mobility and a new type of dynamics of plastic flow in crystalline materials.

Track membranes

Track membranes allow one to create tip electrode nanostructures that release molecular hydrogen 100 times more intensely than traditional electrode systems. The Institute has obtained new products based on track membranes including systems for monitoring drinking water, systems of track-pore room and respirators based on the principle of diffusion gas exchange, tip structures for Raman spectroscopy and for increasing heat removal from reactor surfaces, and membranes for purification of crystallization solutions.

Innovative projects

The experience of the Institute in solid-state physics and the development of technologies of crystal growth paved the way for participation in the State project on the development of an industry of synthetic dielectric crystals and their products. About twenty Russian institutes, industrial enterprises and companies participate in this project. The Institute coordinates the development of new instruments and technologies for the production of synthetic dielectric crystals. The new technology is based upon fundamental advances made by the Institute and benefit from past experience and industrial achievements in the field of growth and processing of crystals, and the manufacture of various crystal-based products.

Contact: Mikhail V. Kovalchuk (koval@ns.crys.ras.ru) Translated by L.I. Man

Inorganic Crystal Chemistry at Moscow State University

For 50 years, the Inorganic Crystal Chemistry Laboratory in the Chemistry Department of Moscow State University has performed a full range of scientific studies from the syntheses of compounds to investigations of their structures and physical properties. The laboratory, previously directed by Yuri P. Simanov and Leonid M. Kovba, has been led by Evgeny V. Antipov since 1996.

The laboratory's goals involve the synthesis of new compounds, determination of their three-dimensional structures and correlation of structure and properties. Powder diffraction is used for phase analysis and cell parameter determination, followed by structure solution from either powder or single crystal X-ray data (XRD). For problem cases electron diffraction (ED) together with high resolution electron microscopy (HREM) and/or neutron diffraction are used. Sometimes other methods help to answer specific questions on structural details, and throughout the process measurements of physical properties are performed by collaborators.

The targets of study over the years have been mainly complex oxides. Intensive studies of superconducting complex cuprates in 1987 resulted in the discovery of a family of mercury based cuprates that exhibits the highest known transition temperature. In 1994, this work received the Lomonosov Award of the Moscow State University and the Superconductivity Award of Excellence given by the World Congress on Superconductivity. Our discoveries have included various superconducting copper based oxides, oxycarbonates, oxyfluorides, and superconducting bismithates. When Sr_1-xK_xBiO₃ was synthesized under high pressure it was found that both the symmetry of the unit cell and its superconducting properties depend on potassium content. The highest superconducting transition temperature was found for the composition Sr_0.44K_0.56BiO₃ when the phase crystallizes in a tetragonal unit cell.

The search for substances with colossal magnetoresistance effects resulted in the synthesis of A₂GaMnO_5+δ (A=Sr, Ca, δ ≤ 0.5) phases for the first time. These phases undergo interesting structural and magnetic phase transitions during the oxidation process. It has been shown that compounds with a Brownmillerite type structure crystallize in different space groups. Only the use of electron microscopy and a 3+d dimensional crystallographic approach helped to describe their structures correctly. The space group depends on the orientation of tetrahedral GaO₄ chains and their ordering in adjacent layers. Sometimes, such ordering occurs in a rather complicated manner forming commensurately modulated structures. For the Sr and Ca phases the insertion of extra oxygen resulted in the suppression of Jahn-Teller distortion for MnO₆ octahedra, a change of Ga coordination from tetrahedral to octahedral, and an increase of unit cell symmetry from orthorhombic to tetragonal.

The study of complex cobalt oxides as potential mixed conductors led to the discovery of Sr_0.7Y_0.3CoO_2.62 which has a perovskite-related crystal structure. Its tetragonal unit cell is formed of alternating cobalt oxygen layers. Half of the layers consist of CoO₆ octahedra, others are oxygen deficient tetrahedra with one additional oxygen at the long distance. The structure is considered as intermediate between brownmillerite and perovskite.

Many of these studies would not have been possible without our collaborators. We are grateful to Arne Magneli and Lars Kihlborg (Stockholm University) who were very helpful during the early 90's, a difficult time for Soviet and Russian science. Massimo Marezio and his colleagues (CNRS, France) have been collaborators in the syntheses and structural studies of superconducting complex copper oxides. Phillip Coppens (SUNY, USA) and Vaclav Petricek (Institute of Physics, Czech Rep.) helped us to understand what modulated structures are. Electron diffraction and high resolution electron microscopy studies are still carried out with Gustaaf Van Tendeloo and co-workers (EMAT, Belgium). Structure refinements from neutron data are based on experiments done in Dubna in the Joint Institute on Nuclear Research by the group of Anatoly Balagurov.

Information about the Inorganic Crystal Chemistry Laboratory can be found at www.icr.chem.msu.ru .

Contact: Evgeny Antipov (antipov@icr.chem.msu.ru)

Structural Chemistry, Moscow State University

Under the direction of Leonid A. Aslanov (aslanov@struct.chem.msu.ru), four main directions of research are being pursued in the Laboratory of Structural Chemistry at Moscow State University:

A. The laboratory is involved in the development of methods for structural characterization of polycrystalline materials from powder data in collaboration with H. Schenk (University of Amsterdam)^[1]. Two molecular structures solved recently from powder diffraction data demonstrate our achievements in this area.

1. Evidence for thermal isomerization of compound (I), C₂₄H₁₅N₅O₂, into compound (II) (see Scheme) has been obtained^[2].

2. Elucidation of three-dimensional solid state structures of two modifications of doxazosin mesylate^[3], a commonly used antihypertensive agent, clearly showed the N1 protonation site in anhydrous (A) and hydrated (dG) solid forms, establish the conformations of the doxazosin molecule and define the hydrogen bonding in both forms.

Contact: Vladimir V. Chernyshev (vladimir@struct.chem.msu.ru)

B. Organic compounds containing from two to four cyano-groups are widely used in preparation of photochromic materials and anticancer drugs. Such compounds contain several active chemical centers and participate in a diversity of chemical reactions. A new kind of organic anion, 3-cyano-4-(dicyanomethylene)- 5-oxo-4,5-dihydro-1H-pyrrol-2-olate, was synthesized as a result of the reaction of tetracyanocyclopropane derivatives with an iodide anion. In the crystals of anion-containing organic salts there are various kinds of stacks due to π-π anion-cation or anion-anion interactions^[4].

Contact: Victor A. Tafeenko (tafeenko@biocryst.phys.msu.su)

C. The laboratory studies pathways for mapping reactions of mesoionic (MESOmeric+IONIC) compounds. Mesoionic systems may be transformed to highly reactive oxo(thio-, imino)[3,2-a]pyridinium cations which, in turn, undergo a variety of ring opening/transformation reactions leading to novel classes of heterocyclic compounds. For example, mesoionic azolopyridines are related to the family of condensed munchnones: a) X=S; Y=S, O, NR; b) X=O; Y=S, O, NR, c) X=NR; Y=S, O, NR. Crystal and molecular structures of novel anaesthetic drugs based on quiniline derivatives, novel pesticides based on urea heterocyclic derivatives, and novel radioprotectors based on pyrimidine derivatives were determined by both X-ray and neutron diffraction.

Contact: Victor B. Rybakov (rybakov@struct.chem.msu.su)

D. A number of the traditional dyes and pigments, as well as modern materials for electrooptical and photonic applications and laser dyes, have been studied by means of single crystal and powder X-ray diffraction. Main research directions are the following: tautomeric interconversions in the solid state; intermolecular charge-transfer interactions and π-complexes; crystal packing effects on spatial and electronic molecular structure; crystallochromism, i.e. the difference in color of solid pigments due to molecular packing arrangements.

Contact: Alexandr V. Yatsenko (yatsenko@struct.chem.msu.su)

[1] Zhukov, S.G. et al. (2001). Z. Kristallogr. 216, 5-9. [2] Chernyshev, V.V. et al. (2001). Acta Cryst. C57, 982-984. [3] Chernyshev, V.V. et al. (2003). Acta Cryst. B59, 787-793. [4] Tafeenko, V.A. et al. (2003). Acta Cryst. C60, o62-o64.

Crystallography in Physics, Moscow State University

A chair of X-ray structure analysis was created in 1932 as one of seven chairs in the Physics Department of Moscow State University. In 1953, it became the Chair of Solid State Physics. Department Chairs have included S.T. Konobeevsky, the first Chair, V.I. Iveronova (a winner of the Fedorov prize of Soviet Academy of Science), and M.M. Umansky (a winner of the Lomonosov Prize of Moscow State University).

The current chair, A.S. Ilyushin, is a leader in the field of education programs on condensed matter among Russian Universities. The program combines the teaching of experimental methods (X-ray, Mossbauer etc.) with basic principles of solid state physics (atomic, electronic and defect structures of crystals, dynamics of the crystal lattice, and phase transformations).

From the 1940s through the 70s a group under M.M. Umansky developed an experimental set for X-ray studies of crystal structure which also won a Lomonosov Prize (M.M. Umansky, S.S. Kvitka, and V.V. Zubenko). Recent research has included the development of new methods of X-ray and Mossbauer structure analysis of ideal and real crystals and application of these methods to studies of phase transformations and defects in metals, alloys, semiconductors and multi-layer films; evolution and self-organization of crystals and their electronic structure; and non-equilibrium phenomena and surface layers. Significant results have included:

a) A non-monotonic structural evolution, including a discrete (jump) evolution in the non-equilibrium metal-hydrogen systems was discovered, and a synergetic model was proposed (A.A. Katsnelson, G.P. Revkevich, and V.M. Avdyuhina).

b) An effect of internal magnetostriction in the rare-earth intermetallic compounds was found and its atomic-ionic mechanism was estimated (A.S. Ilyushin).

c) X-ray and Mossbauer diffraction near-edge spectroscopy of crystals and multi-layer films allowed depth-selective studies of atomic and magnetic structure (R.N. Kuzmin, V.A. Bushuev, M.A. Andreeva, and E.N. Ovchinnikova).

d) A wave theory was proposed for 3D internal structure reconstruction in low-absorption non-crystals based on phase-contrast X-ray refraction tomography, featuring orders of magnitude higher image contrast and 1-2 orders lower dose of absorbed radiation (V.A. Bushuev, patented method).

e) Molecular dynamics simulation and ab initio electronic structure calculations were used to study the formation of adsorbed nanostructures on metal surfaces and to predict the physical properties of surface layers (A.A. Katsnelson and V.S. Stepanyuk).

Contact: Albert A. Katsnelson (albert@sols3591.phys.msu.ru)

Crystallography and Crystal Chemistry of Geology, Lomonosov Moscow State University

The Department of Crystallography and Crystal Chemistry of Geology was founded in Lomonosov Moscow State University by G.B. Bokii in 1949. In 1961 N.V. Belov became the head of the department. From 1983 on the department has been headed by V.S. Urusov. Currently the staff consists of 25 teachers, researchers, and engineers. Since its founding, X-ray crystal structure determination of minerals and their synthetic analogues has been the major focus of the department. More than 200 new crystal structures of minerals have been solved. Another important field of activity for this group (Corresponding Members of RAS D.Yu. Puscharovsky, E.L. Belokoneva, O.V. Yakubovich, Yu.K. Egorov-Tismenko, N.A. Yamnova, and N.V. Zubkova) is mineral systematics and classification based on their structural characteristics, especially crystal chemistry of the main rock-forming minerals: silicates, phosphates, borates, etc.

In the past 2 decades precision X-ray diffraction studies and electron density distribution analysis in oxide and silicate minerals have also been conducted (V.S. Urusov, E.L. Belokoneva, O.V. Yakubovich, N.N. Eremin). Another group of scientists (Yu. K. Kabalov, N.V. Zubkova) is deeply involved in modern powder diffraction methods using Rietveld refinement of mineral crystal structures.

A central point in the domain of theoretical crystal chemistry is occupied by the development of energetic analysis of stability and properties of pure crystals and solid solutions. Recent activities of the group (V.S. Urusov, N.N. Eremin) have concentrated on the problem of computer modeling of structures and properties of mineral and inorganic solids using semi-empirical interatomic potentials as well as on the development of atomistic and phenomenological theory of isomorphous substitutions. Their original approach is minimization of crystal atomisation energy which accounts for the actual character of chemical bonds in crystals.

In addition to crystal chemistry and X-ray diffraction groups, the department includes two laboratories doing single crystal growth: growth from high-T complex flux melts (N.I. Leonyuk, V.V. Maltsev) and growth from hydrothermal solutions (O.V. Dimitrova). Most crystals obtained in these laboratories possess technologically useful properties, e.g. lasers, fiber optics, ferroelectrics, high-T superconductors, superionic conductors, etc. Many have been the subjects of detailed crystal structure determination.

The department is responsible for the crystallographic education of all students (about 200 per year) of the Geological Faculty of Moscow State University as well as for the special education of bachelors, masters and PhD students in the field of crystallography and crystal chemistry (5-6 students and 3-4 post-graduate students per year). Courses include general crystallography, theory of symmetry (Yu. K. Egorov-Tismenko), introduction to crystal chemistry and advanced theoretical crystal chemistry (V.S. Urusov, N.N. Eremin), X-ray diffraction and crystal structure analysis (D.Yu. Puscharovsky, N.N. Zubkova), crystal morphology (G.I. Dorokhova), and crystal growth (N.N. Leonyuk, E.V. Koporulina).

In recent years the following text-books (in Russian) have been published by the teachers in the department: 'Crystallography' (1992) by Yu. Egorov-Tismenko et al., 'Theory of crystal symmetry' (2000) by Yu. Egorov-Tismenko & G. Litvinskaya, 'Theoretical crystal chemistry' (1987) by V. Urusov, 'X-ray diffractometry' (2000) by D. Puscharovsky, 'Structural types of minerals' (1990) by D. Puscharovsky & V. Urusov, 'Design of probable crystal structures of minerals' by V. Urusov et al.

Contact: Vadim S. Urusov (crystal@geol.msu.ru)

Crystal Chemistry, Lomonosov Moscow State University (MSU)

The laboratory was established in 1952 by G.B. Bokii, and first directed by M.A. Porai-Koshits. The current head of the laboratory is Peter M. Zorky and all students (200 to 250) of the department take the crystal chemistry course each year, which includes:

The study of crystal chemistry is not limited to crystallographic point and space groups, but has been expanded to include non-crystallographic axes and the symmetry of rods and slices.

A considerable portion of the course is dedicated to organic crystal chemistry and includes the following subjects: symmetry and structural classes of homo- and heteromolecular crystals; theory of close packing of molecules; calculation of the energy of intermolecular interaction in the atom-atom approximation; specific intermolecular contacts and their aggregation (hydrogen bonds, halogen-halogen contacts, and specific contacts involving benzene rings); and revelation of molecular aggregates in organic crystals; the influence of molecular aggregation on the properties of solid and liquid organic substances. The mastering of crystal chemistry requires visualization of structures (with the use of real ball-and-stick models, slides and animation).

Since the 1970s theoretical studies in the field of organic crystal chemistry conducted under the direction of P. M. Zorky Crystal Chemistry, Lomonosov Moscow State University (MSU) have been a primary research focus. He has developed a topological classification system for organic crystal structures as ordinary, unordinary, and extraordinary, viewing molecular aggregation as optimal arrangements rather than molecular packing, and studied the coexistence of difficult conforms in the same crystal and the presence of common aggregate forms in difficult polymorphic hydrates or solvents. It is likely that the fragments of molecular aggregates that are present in crystals are retained in melts and in solutions, which is the cause of the microheterogeneity of liquid phases.

Correlations between the structures of liquids and crystals are another basis for generalization of crystal chemistry and the exploration of the interdependence of pharmacokinetical properties of drugs, crystal formation, and molecular aggregation in solution, computer simulation of the structures of solutions, and the interpretation of their melting temperatures, measurement of light scattering and of acoustic speeds in organic liquids and in their mixtures.

One of the most recent studies carried out in the laboratory of crystal chemistry is the refinement of the values of van der Waals radii of organogenic elements on the basis of the statistical treatment of structural data taken from 10000 crystal structures in the CSD.

Contact: Peter M. Zorky, (zorkii@cryst.chem.msu.su)

High-resolution protein structure at the Institute of Bioorganic Chemistry, RAS, Moscow

Research directions include X-ray studies of structure function relations of enzymes, molecular aspects of protein-carbohydrate and antibody-antigen interactions.

The crystal structure determinations (resolution 2.1 Å) of a series of Ca⁺⁺, Mn⁺⁺ containing protein - pea lectin in complex with gluco- and mannopyronoside derivatives have revealed the stereochemical features of the binding site responsible for carbohydrate recognition and binding. Based on the determined structure, residue mutations were proposed to change carbohydrate specificity.

The three-dimensional structure (resolution 2.4 Å) of serine protease and bovine duodenase demonstrated the structural features of the active site compatible with effective accommodation of P1 residues typical of trypsin (Arg/Lys) and chymotrypsin (Tyr/Phe) substrates. These specificities in the past were considered to be mutually exclusive. The computer modeling of the complexes with the corresponding octapeptide substrates confirmed the experimental conclusions. The obtained results may permit design of enzymes with a specific ratio of trypsin and chymotrypsin activities.

The crystal structure of the Arg32His mutant of the human tumor necrosis factor (TNF-a), an important immune mediator, has been established at 2.5 Å. Models of the structure complexed with P55 and P75 receptors explained the decrease in its cytotoxic activity. The three dimensional structure of the antigen binding fragment of a monoclonal antibody to human interleukin-2 complexed with antigenic nonapeptide has been determined at 3 Å resolution. Antibody-antigen complexation involves a significant rearrangement of the epitope containing region of the interleukin-2 with retention of the α-helical character of the epitope fragment.

Contact: V.Z. Pletnev, (pletnev@ibch.ru)

Macromolecular crystallography in Pushchino

The Institute of Mathematical Problems of Biology (IMBP) (www.impb.ru) was founded in the Pushchino Biological Centre of the Academy of Sciences in 1972 to create a link between mathematicians, computer scientists and biological laboratories interested in using mathematical and computer tools. A special program for development of protein crystallography was launched in 1976 that required huge computer support. The IMPB group spent its early years in close collaboration with the crystallographic laboratory (headed by Yu. Chirgadze) of the Institute of Protein Research (Pushchino), and benefitted from the advice of V. Borisov (Institute of Crystallography, Moscow). This era ended in the early 80's with the creation in Pushchino of a computational environment that supported all stages of macromolecular structure investigation, including model refinement (protein structure solution was not a routine procedure in those days).

Subsequently, the activities of the laboratory (see www.impb.ru/lmc for more details) have concentrated on development of new mathematical approaches and software for macromolecular crystallography, and collaboration with different laboratories on macromolecular structures. In particular, the laboratory has facilitated the use of the maximal likelihood principle in macromolecular crystallography (1982), the use of electron density histograms (1986) and the use of mixed (hybrid) electron density models (1984) for phase improvement etc. Most recently the main activity of the laboratory has concentrated on the development of ab-initio phasing methods suitable for low and middle resolution stages of crystallographic studies of macromolecular objects.

Contact: Vladimir Y. Lunin (lunin@impb.psn.ru)

Institute of Solid State Physics of the RAS

The ISSP RAS was founded in 1963 by George V. Kurdumov and Yurii A. Osipyan at the Research Center Chernogolovka in beautiful forests near Moscow. The focus of ISSP activities are: condensed-matter physics, materials science and new technologies. The Institute has laboratories for structural analysis by XRD and electron diffraction techniques. Microstructure investigations are carried out by the methods of X-ray spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HREM), scanning electron microscopy (SEM) and Mossbauer spectroscopy. Most of the facilities have low (liquid helium) and high (up to 2000^oC) temperature capabilities. The staff includes five Doctors of Sciences, 12 PhD scientists, and 2-4 post-graduate students.

A variety of crystallographic problems are under investigation.

Crystallography of phase transformations and aperiodic crystals

Since 1930s the name of Kurdumov has been associated with non-diffusion (martensite) transformations in steels and 'shape memory' effect in alloys. Today these ideas open up a large and diverse field of experimental research. Transformations connected with the cooperative motion of atoms occur in many crystal families. Data on structural changes at temperatures down to 4.2 K, under mechanical loading, in electric fields, and under optical pumping have been obtained from metals, dielectrics, ferroelectrics, and HTSC materials. Experts in the laboratory have studied domain systems in A-15 alloys and in high-Tc compounds; the para-ferro-electric transitions in KDP and perovskite crystals; and transformations of polytypic systems of ZnS by oriented loading.

Another current focus is analysis of aperiodic crystals. The invar effect in incommensurate phases, i.e. the zero-coefficient of thermal broadening in the temperature region of the IC phase has been established. A new type of incommensurate composite structures has been discovered in (Rb_x(NH₄)_(1-x))₂SO₄ crystals. These composites exhibit incommensurability of host and guest substructures along all three crystallographic directions. To define the structure and properties of such composites, we examine changes in the structures as a function of temperature, pressure and electrical field. A sequence of phase transitions from an incommensurate composite phase into commensurate ones has been detailed and we have shown that the oriented stress causes the phase transition in the host or guest structure.

Contact: V. Shekhtman, I. Shmytko (shekht@issp.ac.ru; shim@issp.ac.ru)

Structure analysis of high pressure phases

The high-pressure X-ray diffraction group is engaged in the study of phase transitions in metallic alloys. A series of intermetallic phases was synthezied under pressure and crystal structures analyzed. The concept of Brillouin zone - Fermi sphere interactions is applied to account for phase stability in sp metals and alloys. Enhanced Hume-Rothery arguments under high pressure are shown to be responsible for structural complexity in 'simple' metals. For instance, the Li-cI16 phase [Hanfland et al. (2000) Nature 408, 174] is related to the classical Hume-Rothery phases with the Fermi surface close to the Brillouin zone boundaries.

Contact: Valentina F. Degtyareva (degtyar@issp.ac.ru)

Structure analysis of low-dimensional organic conductors

The group, headed by R. Shibaeva, is studying the relationship between the crystal structures and physical properties of low-dimensional organic conductors. X-ray studies of organic radical cation salts with π-organic donors and various anions have been conducted. Compounds under investigation include semiconductors, organic metals with an M-I transition, stable organic metals and organic superconductors. The structural origin of first-order phase transitions are established, electronic band structures calculated, and theoretical and experimental electronic structures compared. Detected regularities in the structure of organic metals led to the development of some prescriptions for direct synthesis. Recently we have begun to study hybrid materials that combine π-electron donor networks, responsible for electronic conductivity, with counterion networks having distinct physical properties (magnetism, photochromism,etc.). Radical cation salts of organic π-donors with the photochromic metal mononitrosyl complexes and magnetic metal oxalates as counterions have also been studied.

Contact: R. Shibaeva, S. Khasanov, L. Zorina (shibaeva@issp.ac.ru)

Amorphous and nanocrystalline systems

Metal-metal and metal-metalloid systems in amorphous and nanocrystalline states are being studied by X-ray diffraction and transmission and high resolution electron microscopy. Samples are produced by controlled crystallization of metallic glasses. Structure stability and evolution have been studied in Fe-, Co-, Ni-, Pd-, Al-, Mg-, Cu-, Zr-based alloys after the decomposition of amorphous alloys prepared by melt quenching. The Al-Ge, Zn-Sb systems were investigated under crystallization of an amorphous phase produced by high pressure with subsequent quenching to liquid nitrogen temperature. The grain size of the nanocrystals is 5-20 nm and the X-ray diffraction pattern contains broadened reflections for small nanocrystals (about 1-5 nm) the X-ray diffraction pattern (Figure below, curve b) is close to that of an amorphous phase (curve a). Both diffraction patterns contain only diffuse maxima, but the curves are different. Curve b corresponds to the structure consisting of both the amorphous phase and nanocrystals with the grain size of 1-5 nm. The high resolution electron microscopy image of this structure is shown in the figure. The structure contains a lot of very small nanocrystals. Analysis of the angular dependence of the diffraction line halfwidth allows us to estimate the main contribution to the broadening and draw conclusions about the fine structure of nanocrystals. All nanocrystals have been found to be defect-free, while Ni nanocrystals contain stacking faults, dislocations, microtwins etc.

Contacts: A. Aronin (aronin@issp.ac.ru), G. Abrosimova (gea@issp.ac.ru)

X-ray optics of real crystals

X-ray optical diffraction effects under investigation include diffraction focusing of X-ray Bloch waves in perfect single crystals, dynamic diffraction on bent single crystals, waveguide and channeling effects, and X-ray interferometry in a continuous radiation spectrum. Short-wave hard radiation scattering in a short-range field of deformation has been studied, schemes of focusing X-ray optical elements have been proposed, and specific features of diffraction in disordered quasi-crystals have been investigated. A software package has been written to interpret and simulate diffraction images obtained by Laue, Debye and rolling-crystal methods. The phase velocity of hard electromagnetic radiation in a medium is higher than the velocity of light in vacuum. Therefore the effects of both total external and total internal reflections exist for X-ray waves. Experiments on X-ray dynamic diffraction in limited perfect single crystals have been carried out under the conditions of total internal reflection of a scattered wave from a crystal-vacuum interface. The interference pattern, formed by a sum of the primary and mirror-like reflected scattered waves, is extremely sensitive to weak distortions of the crystal lattice. The results obtained open new prospects for diagnostics of defects in single crystals and development of new elements for X-ray optics.

Contact: Ernest Suvorov, Irina Smirnova, Evgeniy Shulakov (suvorov@issp.ac.ru)

Leonid A. Aslanov

Leonid A. Aslanov was born in St. Petersburg, Russia in 1938 and studied chemistry at Lomonosov Moscow State University. After graduating from the University in 1960 he pursued his interest in crystallography and received his PhD in 1963 based on his studies of the synthesis and crystal structure determinations of ternary sulphides and selenides of alkali earth and some d-transition metals using powder diffraction. He is now employed by the Department of Chemistry of Moscow State University where he started as a junior researcher and is now a full professor.

Between 1965 and 1973 he investigated crystal structures of coordination compounds of rare earth elements and developed, in collaboration with M.A. Poraj-Koshits, a principle for determination of eight-vertexes polyhedra that has had broad application. (J. Struct. Chem. 13, 244 (1972)).

From 1973 to 1987 his research centered on the synthesis and crystal structure determinations of coordination compounds of tin, lead, and antimony and he found, in collaboration with V.S. Petrosyan and O.A. Reutov, a phenomenon of the trans-strengthening of bonds in octahedral complexes of tin and lead which is opposite to trans-effect in transition metal complexes (Zh. Strukt. Khim. 29, 112 (1089)).

From 1979 to 1992 he developed crystal chemical models of atomic interactions (Acta Cryst. B44, 449 and 458 (1988), A45, 661 and 671 (1989), A47, 63 (1991), A48, 281 (1992)). During this period (1981 to 1991) he started an exploration of photocrystallography and together with his collaborators built a specialized four-circle diffractometer (J. Appl. Cryst. 22, 42(1989)), developed software (J. Appl. Cryst. 24, 293 and 910 (1991)) and performed investigations on ferroelectric materials (J. Appl. Cryst. 23, FC1 (1990)). This research was stopped due to lack of financial support in 1992.

Since 1992 he has been doing research in materials science. During the period betwen 1992 and 1998 he proposed, and tested experimentally, an optoacoustic mechanism of latent image formation in silver halide materials (Laser Physics 6,1105 (1996)). Since 1999 he has been studying the crystallization of nanoclusters in ionic liquids.

L.A. Aslanov did postdoctoral research during the 1967-1968 academic year at the University of Sheffield, UK under the supervision of Ronald Mason. He had a Kapitsa Fellowship in 1993 with Judith A.K. Howard at the University of Durham, UK and from 1992 to 2003 he collaborated in the framework of NWO-grants with Henk Shenk at the University of Amsterdam.

L.A. Aslanov is now Vice-President of IUCr, Co-Editor of Acta Crystallographica A, B, C, D, Zeitschrift für Kristallographie and Associate Editor of Crystallography Reviews in addition to activities with other Russian journals and organizations. He has published over 300 papers, 6 books on crystallographic instrumentation, X-ray diffraction, crystal chemistry and another, on ionic liquids, is now in print. He has directed 28 PhD theses.

Hopefully, the articles on 'Crystallography in Russia' presented in this issue of the IUCr Newsletter have begun to provide an accurate picture of crystallography in modern Russia. With these articles, and those to come in the next issue, we will have demonstrated various branches of crystallography: X-ray, synchrotron, neutron instrumentation and methods; development of methods for crystal structure determination based on powder diffraction data; charge density; minerals, small molecules, proteins, aperiodic structures and amorphous materials; crystal growth; crystalline films; high pressure crystallography; Voronoi-Derichlet polyhedra; teaching crystallography and so on and so forth. All comments and remarks should be sent to L.A. Aslanov, Dept. of Chemistry, Moscow State U., 119992 Moscow, Russia; aslanov@struct.chem.msu.ru.