Specific Features of the Structure and the Dielectric Properties of Sodium–Bismuth Titanate-Based Ceramics

The phase formation, specific features, and the dielectric properties of the ceramics of compositions from the region of morphotropic interface in the (Na_0.5Bi_0.5)TiO₃–BaTiO₃ system modified by Bi(Mg_0.5Ti_0.5)O₃ and also low-melting additions KCl, NaCl–LiF, CuO, and MnO₂ that favor the control of the stoichiometry and the properties of the ceramics have been studied. The ceramics are characterized by ferroelectric phase transitions that are observed as jumps at temperatures near 400 K and maxima at T_m ~ 600 K in the temperature dependences of the dielectric permittivity. The phase transitions at ~400 K demonstrate the relaxor behavior indicating the existence of polar domains in the nonpolar matrix. An increase in the content of Bi(Mg_0.5Ti_0.5)O₃ favor a decrease in the electrical conductivity and dielectric losses of the samples, and the relative dielectric permittivity at room temperature ε_rt is retained quite high, achieving the highest values ε_rt = 1080–1350 in the ceramics modified with KCl.     

Specific Features of the Properties of Co–Cu Granular Media Caused by the Structure of the Material

A comparative analysis of rapidly quenched strips and thin films prepared from Co–Cu alloys with giant reluctance is performed. It is established that their microstructure and phase composition differ strongly. Precipitates of Co-enriched phase of two types that differ in their origin and sizes are present in strips. Large particles (100 nm) having the fcc structure determine the magnetic properties, and small particles ( 5 nm) determine the reluctance. In films, Co particles of only one type are detected. They have hexagonal close-packed lattice, can be in superparamagnetic and ferromagnetic states, and yield the corresponding contributions to the giant reluctance. The above-indicated specific features in the microstructure lead to different magnetic and reluctance properties of strips and films.     

The Generating Function for the Components of the Euler–Poinsot Tensor

Doklady Physics - Generating functions that enable us to calculate the components of the Euler–Poinsot tensor using differentiation are introduced. The role of these functions is similar to...     

Topological Expansion in the Complex Cubic Log–Gas Model: One-Cut Case

We prove the topological expansion for the cubic log–gas partition function

$$\begin{aligned} Z_N(t)= \int _\Gamma \cdots \int _\Gamma \prod _{1\le j<k\le N}(z_j-z_k)^2 \prod _{k=1}^Ne^{-N\left( -\frac{z^3}{3}+tz\right) }\mathrm{dz}_1\cdots \mathrm{dz}_N, \end{aligned}$$

where t is a complex parameter and \(\Gamma \) is an unbounded contour on the complex plane extending from \(e^{\pi \mathrm{i}}\infty \) to \(e^{\pi \mathrm{i}/3}\infty \). The complex cubic log–gas model exhibits two phase regions on the complex t-plane, with one cut and two cuts, separated by analytic critical arcs of the two types of phase transition: split of a cut and birth of a cut. The common point of the critical arcs is a tricritical point of the Painlevé I type. In the present paper we prove the topological expansion for \(\log Z_N(t)\) in the one-cut phase region. The proof is based on the Riemann–Hilbert approach to semiclassical asymptotic expansions for the associated orthogonal polynomials and the theory of S-curves and quadratic differentials.

     

Critical Pressure of the Structure I Empty Gas Hydrate

A 368 water molecule structure I empty gas hydrate with possible minimum energy are calculated under high pressures by using TIP4P potential molecular dynamical simulations.Thermodynamical properties are analysed.Radial Distribution function and phonon density of states shows that there is a phase transition to high-density ice at low temperature.     

Vanishing of the Batalin–Vilkovisky Algebra Structure for TCFTs

The purpose of this short note is to show that for topological conformal field theories in dimension two (or closed string field theories) the Batalin–Vilkovisky algebra structure on the homology of the BRST-complex [G] ([Z]) is trivial after a certain element of ghost number 0 is inverted. The important point here is that we do not restrict our considerations to the tree level but incorporate the action of moduli spaces for higher genera. Received: 22 September 1998 / Accepted: 1 March 1999     

Molecular Dynamics Simulation of the Structure I Empty Gas Hydrate

The 368 water molecule structure I empty gas hydrates with three possible hydrogen orientations are calculated using TIP4P potential molecular dynamical simulations.The thermodynamic properties and hydrogen bonding are compared with ice Ih.The density of states is analysed based on experimental measurements.The empty gas hydrate at low temperature is stable without gas molecules encaged.     

Adsorption Properties of β‐Cyclodextrin for Adsorbing Aromatic Hydrocarbons from the Gas Phase and Water

β‐cyclodextrin (β‐CD) is a potentially useful adsorbent for the adsorption of aromatic hydrocarbons from the gas phase and water. In this paper, the adsorption properties of β‐CD for adsorbing six aromatic hydrocarbons from the gas phase and seven aromatic hydrocarbons from water were measured. The inverse gas chromatography (IGC) technique was used to characterize the Flory interaction parameters of β‐CD and the six aromatic hydrocarbons from the gas phase at 40, 50, 60, and 70°C. For these aromatic hydrocarbons, the order of β‐CD adsorption ability from strong to weak was: styrene>ethylbenzene>o‐xylene>chlorobenzene>toluene>benzene. For the seven aromatic hydrocarbons in water, adsorption values α, were measured at 20, 30, 40, and 50°C. The order of β‐CD adsorption ability from strong to weak was: ethylbenzene>o‐xylene>styrene>chlorobenzene>toluene>benzene>phenol. This trend was explained based on their solubility degrees in water. It was found that the adsorption abilities of β‐CD for adsorbing aromatic hydrocarbons from the gas phase and water have a similar trend.     

Thermal Stability of Structure and Properties of Gradient and Gradient-Layered Coatings of the Ti–Al–Si–Cu–N System

Russian Physics Journal - Using the methods of dark-field electron microscopy analysis, energy-dispersive X-ray microanalysis, hardness measurements and scratch testing, the variations of elemental...     

Topological Properties of the Born–Oppenheimer Approximation and Implications for the Exact Spectrum

The Born–Oppenheimer approximation can generally be applied when a quantum system is coupled with another comparatively slower system which is treated classically: for a fixed classical state, one considers a stationary quantum vector of the quantum system. Geometrically, this gives a vector bundle over the classical phase space of the slow motion. The topology of this bundle is characterized by integral Chern classes. In the case where the whole system is isolated with a discrete energy spectrum, we show that these integers have a direct manifestation in the qualitative structure of this spectrum: the spectrum is formed by groups of levels and these integers determine the precise number of levels in each group.     

Large-Time Behaviors of Solutions to an Inflow Problem in the Half Space for a One-Dimensional System¶of Compressible Viscous Gas

The “inflow problem” for a one-dimensional compressible barotropic flow on the half-line R ₊= (0,+∞) is investigated. Not only classical waves but also the new wave, which is called the “boundary layer solution”, arise. Large time behaviors of the solutions to be expected have been classified in terms of the boundary values by [A. Matsumura, Inflow and outflow problems in the half space for a one-dimensional isentropic model system of compressible viscous gas, to appear in Proceedings of IMS Conference on Differential Equations from Mechanics, Hong Kong, 1999]. In this paper we give the rigorous proofs of the stability theorems on both the boundary layer solution and a superposition of the boundary layer solution and the rarefaction wave. Received: 25 April 2000 / Accepted: 20 April 2001     

Gas Transmission Properties of Pd–Ag Membranes Coated with Modifying Layer

Russian Physics Journal - The paper proposes the manufacturing methods for modifying coatings for gas-diffusion membranes made of palladium-silver alloy comprising 23% Ag. Highly developed surface...     

Examples of Asymptotic Solutions Obtained by the Complex Germ Method for the One-Dimensional Nonlocal Fisher–Kolmogorov–Petrovsky–Piskunov Equation

Russian Physics Journal - The general construction of the Cauchy problem solution for the one-dimensional nonlocal population Fisher–KPP equation is briefly described in terms of...     

The Influence of Polyvinylpyrrolidone on the Structure and Optical Properties of ZnO–MgO Nanocomposites Synthesized by the Polymer–Salt Method

Optics and Spectroscopy - The influence of polyvinylpyrrolidone on the structure and optical properties of ZnO–MgO nanocomposites synthesized by the polymer–salt method is studied. The...