Features of Joint Thermolysis of Organometallic Compounds of Group III and V Elements

The kinetic data on thermolysis of equimolar gaseous mixtures of organometallic compounds of Group III and V elements show that the thermal stability of the mixture differs from that of the components taken separately, which is mainly due to complexation between the mixture components. The complex is a kinetically active species. The rate of joint thermolysis of the organometallic compounds grows as the number of hydride atoms at the Group V element increases in the order AsMe3 < t-BuPH₂ < AsH₃. The stability of the complexes formed by organometallic compounds of Group III and V elements decreases in the same order. Joint thermolysis of Me₃Ga and AsH₃ yields a solid oligomer Me₂GaAs(H)Ga(Me)AsH₂. The complicated pattern of decomposition of a mixture of trimethylaluminum with various electron donors is due to participation in the pyrolysis of two trimethylaluminum species: monomeric and dimeric. In decomposition of pure trimethylaluminum or its mixtures with organometallic compounds of Group V elements or with ether, solid pyrolysis products deposited on the vessel walls catalyzed further transformations of the mixture components.     

Kinetics of solid phase thermal polycondensation of aspartic acid in evacuated system

Solid phase thermal polycondensation of aspartic acid in evacuated system results in formation of poly(aspartic acid) at 190–207°C and in poly(succinimide) at 210–230°C. Kinetic parameters of formation of poly(aspartic acid) and poly(succinimide) have been determined. The aspartic acid → poly(aspartic acid) → poly(succinimide) polycondensation is accompanied by partial decarboxylation of the monomeric units.     

The adhesive properties of polyfluoroolefin films modified by direct-current discharge

The influence of the treatment of various structures polyfluoroolefine films by the direct-current discharge at the anode and cathode on the properties of the surface (the value of the contact angles of wettability, work of adhesion, and surface energy and its polar and dispersive components) is studied. Measurements of the peel strength of plasma-treated films are conducted. It is shown that the direct-current discharge treatment makes it possible to substantially increase the peel strength of the polyfluoroolefin films.     

Adhesive properties of plasma-modified polytetrafluoroethylene films

A procedure was developed for the determination of the adhesion characteristics of the modified surface of thin polymer films, including those treated in a low-temperature plasma, with the use of the Scotch® 810 adhesive tape. The procedure comprises coating the surface to be studied by physical vapor deposition with an aluminum layer of ～100 nm thickness, making an adhesive joint of the film with the Scotch® 810 tape, and T-peel testing of the specimen. Using this procedure, the peel resistance of the initial PTFE film and the film modified at the cathode and the anode in dc discharge was measured.     

Homogenization of the Neumann problem for the Lamé equations of linear elasticity in domains with a periodic system of channels of small length

The problem of homogenization is considered for the solutions of the Neumann problem for the Lamé system of plane elasticity in two-dimensional domains with channels that have the form of rectilinear cylinders of length ε ^q (ε is a small positive parameter, q = const > 0) and radius a _ɛ. The bases of the channels form an ε-periodic structure on the hyperplane {x ∈ ℝ²: x ₁ = 0} and their number is equal to N _ɛ= O(ɛ⁻¹) as ε → 0. Under the limit condition lim on the parameters characterizing the geometry of the domain, the weak H ¹-limit of the generalized solution of this problem is found. __________ Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 310–322, 2005.     

X-ray diffractometry and electrical conductivity of the ceramics LaSrAl(Cu,Ni)O4

A continuous series of solid solutions LaSrAL_1−x Me_xO₄ (Me = Cu, Ni) has been investigated by x-ray diffractometry and by electrical conductivity measurements. The results are of interest from the standpoint of the theory of close-packing, percolation theory, and the theory of the cooperative Jahn-Teller effect. Fiz. Tverd. Tela (St. Petersburg) 39, 985–990 (June 1997)     

Spin-spin interactions of Ce3+ ions in the elpasolite crystal Cs2NaInCl6

The EPR method is used to study at T=4.2 K crystals of Cs₂NaInCl₆:Ce³⁺ (1 mol %) at which have elpasolite structure. A solitary cubic Ce³⁺ center and three types of Ce³⁺-Ce³⁺ pairs were observed, for which the spin-spin interaction parameters D and E were determined. It is established that deformation of the local structure results in a shift {Δg} of the pair relative to the g-factor of the solitary center. Models of the solitary center and the three types of Ce³⁺-Ce³⁺ pairs are discussed, as well as the nature of the spin-spin interactions in the pairs. The non-dipole nature of the interactions is established. Possible chains for the creation of an indirect exchange between the Ce³⁺ ions are considered. Fiz. Tverd. Tela (St. Petersburg) 39, 62–67 (July 1997)