Complexes of Some Metal Nitrates with 4′-Nitrobenzo-15-Crown-5

Complexes of Ag, Cu, Ca, Nd, and Er nitrates with 4-nitrobenzo-15-crown-5 (NB15C5) were synthesized and their IR absorption spectra were studied. Macrocyclic conformation in the complexes was determined. The structures of the complexes were proposed with account of the data of IR absorption spectra and of the previous X-ray diffraction study. In the Ag, Cu, and Ca complexes, NB15C5 was found in the inner sphere, while in the Nd and Er complexes, it was found to be the outer-sphere ligand.     

Complexes of Li,Na, Ba,and Er with 1,5-Bis[2-(diphenylphosphinyl)phenoxy]-3-oxapentane

Complexes of Li, Na, Ba, and Er with 1,5-bis[2-(diphenylphosphinyl)phenoxy]-3-oxapentane (L) were synthesized and their IR spectra were examined. Some of the complexes were studied by thermogravimetric methods. The structures of the synthesized compounds were suggested on the basis of their spectra and previous X-ray studies. In Ba and Er complexes, L was found to be coordinated to the metal atom through the phosphoryl oxygen atoms, whereas in Li and Na complexes, both the phosphoryl and anisole oxygen atoms are involved in coordination. The structures of complexes was determined to depend on the nature of a metal and acidoligand and on the ratio of reagents used in the synthesis.     

Mechanisms of plastic deformation,hardening, and fracture in single crystals of nitrogen-containing austenitic stainless steels

We have carried out a systematic investigation of the mechanisms for solid-solution hardening by nitrogen atoms and dispersion hardening by nitride particles in single crystals of austenitic stainless steels with different stacking fault (SF) energies _SF=0.02–0.2 J/m². We show that alloying with nitrogen C_N=0–0.7 mass % and precipitation of dispersed particles leads to the appearance of an orientation dependence of the critical shearing stresses _cr, asymmetry phenomena, an orientation dependence of the slip and twinning deformation mechanisms, superelasticity, and transition from ductile fracture to brittle fracture. We develop dislocation models for solid-solution hardening by interstitial atoms, the orientation dependence and the asymmetry of _cr, based on taking into account the effect of the external stress field on the splitting of a/2110 dislocations into partial Schockley a/6211 dislocations and the change in the position of the interstitial atoms from octahedral interstitial sites to tetrahedral sites with a shift of the twinning a/6211 dislocations by a Burgers vector. We establish the role of strain localization, splitting of gliding dislocations, twinning, and a high stress level in creation of strain hardening, plastic flow instabilities, and the conditions for the "brittle-ductile" transition.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 5–32, March, 1996.     

Effect of black carbon particles on the efficiency of water droplet freezing

Black carbon particles emitted by natural and anthropogenic sources of combustion are potential nuclei of ice formation of cirri in troposphere. The freezing of the ensembles of water microdroplets containing black carbon particles of different origins, including those modified with organic substances, is studied. Ice-forming ability is shown to be predetermined by the density and sizes of black carbon agglomerates, as well as the chemistry and wettability of their surface. Ice formation is most efficient in dispersions of black carbon particles that are stable with respect to sedimentation and have a uniform distribution of particles over the droplet volume. In the presence of oxygen-containing groups on the particle surface, freezing temperature increases. The efficiency of the ice formation decreases in the presence of noticeable amounts of water-soluble substances on the particle surface. The maximum freezing ability is inherent in ensembles of water droplets containing hydrophilic particles. Characteristics ensuring a high ice forming ability of nuclei are determined.     

Free Radical Hydrophosphorylation of Fluoroalkyl Vinyl Ethers: Synthesis of Fluoroalkyl Phosphonates

An effective method for the synthesis of dialkyl [2-(polyfluoroalkoxy)ethyl]phosphonates by free radical hydrophosphorylation of fluoroalkyl vinyl ethers with dialkyl (H)-phosphonates was developed. The reaction proceeds in the presence of catalytic amounts of azabisisobutyric acid dinitrile (AIBN) (150°C, 2 h, portionwise addition of AIBN) to afford the target fluoroalkyl phosphonates in up to 85% isolated yield.     

Physicomechanical properties of the surface of a zirconium alloy modified by a pulsed ion beam

The physicomechanical properties of the surface of the Zr-1% Nb zirconium alloy modified by a pulsed carbon ion beam with a pulse duration of 80 ns, an energy of 200 keV, and a current density of 120 A/cm² are studied at four regimes having different numbers of pulses. Irradiation by a carbon ion beam results in hardening of the surface layer to a depth of 2 μm, grain refinement to 0.15–0.8 μm, zirconium carbide formation, and a decrease in the hydrogen permeability of the zirconium alloy.     

Formation of platinum sites on layered double hydroxide type basic supports: II. Effect of the nature of the interlayer anion of the layered aluminum-magnesium hydroxides on platinum binding and Pt/MgAlO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> formation

The interaction of aqueous H₂PtCl₆ solutions with hydrotalcite-type aluminum-magnesium hydroxides differing in the nature of their interlayer anion is reported. In the case of CO₃²⁻ as the interlayer anion, the introduction of the platinum(IV) chloro complex does exerts no significant effect on the structural properties of the support, on its thermal decomposition dynamics, and on the textural characteristics of the resulting oxide phase. The binding of the platinum complexes to “activated hydrotalcite” with interlayer OH⁻ anions increases the interplanar spacing and enhances the thermal stability of the layered structure. This is accompanied by marked changes in textural characteristics of the material, leading to the formation of a nearly monodisperse mixed oxide phase. In the Pt/MgAlO _x samples obtained by reductive treatment, a considerable proportion of platinum is in the form of planar particles, and this corroborates the hypothesis that the metal complex at the sorption stage is mainly localized in the interlayer space of this support. Platinum binds to the support as chloro complexes via rapid anion exchange, and these bound platinum species are characterized by a higher reduction temperature.     

High-temperature superelasticity in CoNiGa,CoNiAl, NiFeGa,and TiNi monocrystals

The influence of the crystal orientation on the thermoelastic martensitic transformations developing under load was investigated for Co₄₉Ni₂₁Ga₃₀, Co₄₀Ni₃₃Al₂₇, Co₃₅Ni₃₅Al₃₀, Ni₅₄Fe₁₉Ga₂₇, and Ti_49.4Ni_50.6 (аt. %) monocrystals. It has been shown that the superelastic temperature range depends on the crystal orientation and reaches a maximum for [001]-oriented crystals. In monophase crystals of Co₄₉Ni₂₁Ga₃₀, Co₄₀Ni₃₃Al₂₇, Co₃₅Ni₃₅Al₃₀, and Ni₅₄Fe₁₉Ga₂₇ (at. %), segregation of dispersion particles takes place at test temperatures T > 623 K. A criterion for high-temperature superelasticity has been proposed which implies the attainment of high strength of the high-temperature phase due to a proper choice of the crystal orientation, deviation from stoichiometry, and segregation of dispersion particles. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10. pp. 19–37. October, 2008.