Cocrystallization of Cu2+ with NH4Cl by the anomalous isomorphism mechanism

In the ammonium chloride crystallization region of the NH₄Cl−CuCl₂−H₂O−CH₃ON system, cocrystallization of the impurity with the main substance occurs by epitaxial adsorption of complexes of varying composition. In NH₄Cl crystals, the Cu²⁺ impurity forms oriented interlayers (ingrowths) simultaneously at the macro-and microlevels. The ratio between the two trapping forms depends on the growth conditions. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 70–78, September–October, 1994. Translated by L. Smolima     

Growth Actuated Bending and Twisting of Single Crystals

Crystals of a variety of substances including elements, minerals, simple salts, organic molecular crystals, and high polymers forgo long‐range translational order by twisting and bending as they grow. These deviations have been observed in crystals ranging in size from nanometers to centimeters. How and why so many materials choose dramatic non‐crystallographic distortions is analyzed, with an emphasis on crystal chemistries that give rise to stresses operating either on surfaces of crystallites or within the bulk.     

Investigation of the effect of large-scale shell asymmetry on Iskra-5 target operation

Experiments designed to investigate the effect of a controlled large-scale asymmetry of a shell containing deuterium-tritium fuel on the shell compression and neutron production under indirect (x-ray) action are performed on the Iskra-5 laser fusion device. The uniformity of the x radiation near the target is not worse than 3%, and the shell asymmetry is varied from 30 to 100%. The observed decrease of the experimental neutron yield as compared with experiments using symmetric targets is in satisfactory agreement with two-dimensional calculations. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 3, 161–165 (10 February 1998)     

Generation of the line radiation of argon added to DT gas in Iskra-5 experiments

The first experiments measuring the density of a compressed deuterium and tritium mixture in microtargets of indirect irradiation (x-ray targets) were performed at the Iskra-5 facility. The density was determined according to the broadening of the lines of hydrogen-and helium-like argon added to the DT gas as a diagnostics material. A series of three experiments was performed with x-ray targets in which the central capsule filled with a DT + Ar mixture over a range of shell thicknesses. In two of the experiments, argon emission spectra were recorded and the density of the compressed gas was determined. For a microtarget approximately 280 μm in diameter with a wall approximately 7 μm thick, an analysis of the experimental results yielded an estimated density in the compressed gas of ∼1 g/cm³. Gas-dynamic calculations using the SNDA (spectral nonequilibrium diffusion with absorption) program show that argon emission takes place just after reaching maximum temperature, but much sooner than maximum compression. The results of a calculation for an experiment with low relative Ar concentration are in overall agreement with the experimental data. Additional investigations are needed to interpret experiments at a relatively high concentration. Zh. éksp. Teor. Fiz. 114, 837–848 (September 1998)     

Physical and physicochemical processes accompanying powder synthesis, growth of PbMoO4 crystals, and their annealing in various media: VI. Anomalous biaxiality and thermoplastic stresses in PbMoO4 crystals in the relationship with the growth conditions

The optical anomalies are investigated and the internal stresses are calculated for lead molybdate crystals grown by the Czochralski method. An effect of the growth conditions on the distribution of stresses in the crystals is revealed.     

Anomalous crystal optics of heterogeneous crystals

Various approaches to analysis of the characteristics of optically heterogeneous crystals (with the characteristic thicknesses of layering lamellae exceeding the light wavelength) are considered in the example of layered two-component heterogeneous structures. In the simplest cases, the quantitative information on the layering structure may be obtained from analysis of numerical characteristics such as the moments of the appearance of visible isogyres or the positions of isotropic compensation points. In more complicated cases, it may be reasonable to use the program specially written by the authors for constructing conoscopic figures of heterogeneous crystals. Finally, the heterogeneity of complex crystals may be characterized proceeding from the qualitative estimate of the degree of distortion of their conoscopic figures.     

Optical anomalies and residual stresses in basal-plane-faceted ribbons of Stepanov-grown sapphire crystals

The effects of an anomalous biaxiality and a residual-stress field in basal-plane-faceted single-crystal sapphire ribbons were studied by an optical polarization method using a conoscopic light beam. Formulas that relate the difference between the principal stresses to the angle of optical-axis divergence are obtained. It is shown that the central regions of the ribbons undergo compressive stresses whereas their edges undergo tensile stresses. As compared to block-free ribbons, the stresses in block-containing ribbons increase more intensely with distance from the seed.     

Optical dissymmetry in crystals due to inhomogeneous distribution of isomorphous components

The mechanisms of optical dissymmetry (optical anomalies) due to inhomogeneous trapping of isomorphous impurities into a crystal are considered using water-soluble systems of potassium dihydrophosphate-ammonium dihydrophosphate and alum as an example. St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 5, pp. 60–69, September–October, 1994. Translated by L. Smolina     

Fundamental nuclear physics research at RFNC VNIIEF over 60 years

The role of fundamental nuclear physics research in development of nuclear weapons is considered. The main characteristics of the experimental facilities of the Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics are reported.