Influence of magnetic fields upon phase transformations in solid state ionic systems

The driving force for phase transformations in solids can be modified by the presence of magnetic fields. The basic principles involved in this effect are presented. It is shown how changes in the magnetic contribution to the total Gibbs free energy are related to other parameters, such as the activities of mobile species, the potentials of solids in electrochemical systems, and the temperature dependence of phase equilibria. The application of this effect in solid state ionic systems containing mixed ionic-electronic conductors with high rates of chemical diffusion, such as metal hydrides, is discussed. Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995     

Equations from non-linear chiral transformations

In comparison with theWT chiral identity which is indispensable for renormalization theory, relations deduced from the non-linear chiral transformation have a totally different physical significance. We wish to show that non-linear chiral transformations are powerful tools to deduce useful integral equations for propagators. In contrast to the case of linear chiral transformations, identities derived from non-linear ones contain more involved radiative effects and are rich in physical content. To demonstrate this fact we apply the simplest non-linear chiral transformation to the Nambu-Jona-Lasinio model, and show how our identity is related to the Dyson-Schwinger equation and Bethe-Salpeter amplitudes of the Higgs and π. Unlike equations obtained from the effective potential, our resultant equation is exact and can be used for events beyond the LEP energy.     

New bismuth ion conducting solid electrolyte

A new trivalent bismuth ion conducting solid electrolyte, (Bi_xGe_1 − x)_{4/(4 − x)}Ta(PO₄)₃, was successfully developed by selecting the NASICON-type GeTa(PO₄)₃ as the mother solid. Although bismuth has two kinds of valence states of + 3 and + 5, it was clear that pure trivalent Bi³⁺ ion conduction, without any electronic conduction by a valence change of bismuth in the oxygen pressure range over 10^− 3 Pa, was realized by selecting the crystal structure and constituents of the solid.     

Equations of state and the parameters of interatomic interaction potentials for six metals which experience phase transformations in stress waves

For six metals which experience phase transformations in stress waves, Fe, Cr, Hf, Pb, Ti, and Zr, equations of state have been obtained with the use of the Lennard-Jones interatomic interaction potential for low pressure and high pressure phases. For the low pressure phases, the parameters of the potential were calculated with the use of a complex of physical characteristics which are determined for the unstrained sample under normal conditions. The parameters of therelations D(u) and P(x) for the high pressure phases were determined from the data of a shock-wave experiment with observance of requirements for their consistency. The approximations obtained for the high pressure phases enable one to calculate the compressibility with the density increment measured with an error no more than 6% and the velocity of propagation of the shock wave with an error of 4% up to about twofold compression. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 57–60, October, 2006.     

Martensite transformations and phase diagram of solid methane

Processing of the data of x-ray investigation of the diffraction scattering function of the 311 reflection in the temperature range 6–30°K shows that the phase transformation in methane is of the martensite type. The martensite points M_s and M_f limiting the region of the heterophase are determined on the phase diagram. The 16-molecule bct cell established in the-phase of CD₄ as well as the manifestation of birefringence in CH₄ and its isotopes leads to the conclusion that in these substances, as a result of molecular ordering, a lattice rearrangement from fcc to bct takes place, in accordance with the Bain orientation. The existence of an intermediate phase which is unstable in methane but stable in all its isotopes explains the presence respectively of one and two -anomalies in the specific heat.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 58–64, March, 1984.The authors are grateful to L. V. Skibina and M. M. Chernik for discussion of the results, and V. B. Filatova for assistance in the design of this experiment.     

Phase transition of solid bismuth under high pressure

As a widely used pressure calibrator, the structural phase transitions of bismuth from phase I, to phase II, to phase III,and then to phase V with increasing pressure at 300 K have been widely confirmed. However, there are different structural versions for phase III, most of which are determined by x-ray diffraction(XRD) technology. Using x-ray absorption fine structure(XAFS) measurements combined with ab initio calculations, we show that the proposed incommensurate composite structure of bismuth of the three configurations is the best option. An abnormal continuous increase of the nearest-neighbor distance of phase III with elevated pressure is also observed. The electronic structure transformation from semimetal to metal is responsible for the complex behavior of structure transformation.     

Structural-phase transformations in low-stability condensed state systems

The conditions of formation of low-stability condensed state systems, their behavior and structure are investigated. The objects under study are alloys and compounds undergoing structural-phase transitions of the second type or close to it. The low-stability (pre-transitional) state is treated here as the state of a system near its structural-phase transformations, in which its structure and properties exhibit anomalies. An attempt is made to interpret the system from the physical standpoint relying on a new insight into its state, in which the traditionally accepted phase-transition point is represented by a range of values of the parameter controlling the transition. The material state within this range of values is structurally weakly stable in terms of slight variations in the controlling parameter. It is shown that the thermodynamics of structural-phase transformations of the material in this transient state is significantly affected by the interaction of structure defects.     

Quantum state transformations and the Schubert calculus

Recent developments in mathematics have provided powerful tools for comparing the eigenvalues of matrices related to each other via a moment map. In this paper, we survey some of the more concrete aspects of the approach with a particular focus on applications to quantum information theory. After discussing the connection between Horn’s Problem and Nielsen’s Theorem, we move on to characterizing the eigenvalues of the partial trace of a matrix.     

Ultrafast dynamic compression technique to study the kinetics of phase transformations in bismuth

Preheated Bi (296-532 K) was ramp compressed with 15-35 ns rise times to a peak stress of approximately 11 GPa to explore structural phase-transformation kinetics under dynamic loading conditions. At high strain rates, epsilon[over ]>5 x 10;{6} s;{-1}, deviation from equilibrium phase boundaries suggests that compression time scales are comparable to the new phase incubation period. The dependence of DeltaP/kT on epsilon[over ] is consistent with a thermally activated transformation.     

An XPS study of the valence bands in solid and liquid bismuth

High resolution XPS measurements on bismuth show the valence band structure of the liquid phase to be very similar to that of the solid and very different from that of free electrons. The spectra are in general accord with recent calculations of the densities of states for crystalline and amorphous group V elements.     

铋的固相及液相多相状态方程研究

铋在高温高压下存在一系列复杂相结构,相变伴随着密度、内能等物理性质的改变.采用半经验三项式Helmholtz自由能表达式,构建了铋的五个固相及液相的多相状态方程,其中离子热振动自由能计算基于经典平均场理论给出的平均场势函数模型开展.研究结果表明,状态方程计算给出的铋的相图、等温压缩线、液相的温度-密度曲线以及冲击Hugoniot线等均与实验测量符合较好,故可认为本文构建的铋的多相状态方程具有良好的参数合理性以及模型适用性.     

Equations of electrodynamics in a rotating solid dielectric

The equations of electrodynamics in a rotating isotropic homogeneous dielectric are obtained in a covariant form in coordinates of a reference frame that accompanies the rotation of the dielectric. It is found from these equations, which have variable coefficients, that the medium of the rotating dielectric is anisotropic and inhomogeneous. To derive tensors of the electromagnetic field in a rotating reference frame (RRF), the fields and inductions of a virtual inertial reference frame (IRF) that instantaneously accompanies the motion of one of the points of the dielectric are used twice. Initially, using instantaneous local relations, they are expressed in terms of real fields and inductions of the rotating medium, and then they are transformed into fields and inductions of a stationary IRF, in which they are used as components of the tensors of the electromagnetic field. Thus, the electromagnetic field tensors in the IRF are determined taking into account a priori unknown real inhomogeneous permittivity \(\bar \varepsilon \) and permeability \(\bar \varepsilon \) of the rotating medium. At the final stage, the tensors in the RRF are obtained by transformation rules for covariant and contravariant tensor components in accordance with known analytical relationships of fixed and rotating coordinates. The properties of modes of a rotating ring resonator in the form of homogeneous TE waves that travel along and against the direction of rotation and, in particular, their normal frequencies are examined. The contribution of inhomogeneous properties of the medium of a rotating dielectric to the difference between the normal frequencies of the counterpropagating waves (to the Sagnac effect) is determined. In a solid material with known elastic and striction characteristics, its density and dielectric permittivity depend on the radial coordinate. These dependences are caused by the action of the centrifugal force and changes in the polarization and magnetization of the medium because of the rotational motion of charged particles. The coordinate dependences of permittivity \(\bar \varepsilon \) and permeability \(\bar \varepsilon \) make additional contributions to the inhomogeneous properties of the medium of the rotating dielectric and to the Sagnac effect.     

Dynamics of spin state conversion processes in the solid state

Hyperfine Interactions - High spin (HS) ⇌ low spin (LS) conversions in transition metal complexes are nonradiative transitions between spin states. In this contribution, we present a study of...     

Equations of state for strong compression

Abstract

Various higher order equations of state (EOS) are compared with theoretical predictions for strong compression as well as with different linearization schemes. One specially convenient EOS together with a conjugated linearization scheme is presented as a series expansions with the appropriate asymptotic behaviour at very strong compression. Tests for the uncertainties in EOS extrapolations are discussed. A comparison with literature data for highly compressible solids illustrates the advantages of the present EOS with respect to many other commonly used forms.     

Primary solid state batteries

Low - cost, easily fabricated dry cells were constructed by gluing a composite conducting material or a metal sulphide on magnesium or aluminium foils, using a solid electrolyte made from polyvinyl - pyrolidone. Composite conducting materials consisted of polypyrrole and polyaniline incorporated into an inorganic or polymer matrix or cupric oxide incorporated into a styrene - butadiene copolymer matrix. The efficiency, energy densities and voltage values of the cells were in the range 0.5 – 18.3 mWh cm⁻³, 9 – 339 wh kg⁻¹ and 0.5 – 2.0 V, respectively. The energy densities of the cells were up to seventeen times more than the energy density of the PbO₂ -H₂SO₄ - Pb multiple charge / discharge system and up to ten times more than the energy density of the nickel / cadmium rechargeable cell. A dry cell composed solely from polymers was constructed with cell voltage 0.25 – 0.50 V and efficiency ranging from 0.07 to 0.13 mWh cm⁻³ ten times lower than other commercial cells. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11–18 Sept. 1994     

Representations of state space transformations by Markov kernels

Every convex subset of a locally convex Hausdorff space (X, ) is equipped with the (-algebra generated by its-relatively open subsets. Within the set () of probability measures on two particular convex subsets are considered: (a) the set ^s () of probability measures with a separable support, and (b) the set ^c () of probability measures with a compact convex support. If is the base of a cone inX, then there exists an affine barycenter map from ^c () onto whose composition with the natural embedding of in ^c () yields the identity map on , and every-continuous affine transformation of can be represented by an affine transformation of ^c () that is induced by a Markov kernel. If (X, ) is a Banach space and is a closed, bounded, generating cone base inX that is contained in a hyperplane, then analogous results are obtained with respect to ^s (). Since the state spaces considered in noncommutative measure theory are cone bases and every change in time of an empirical system can be thought of as an affine transformation of the associated state space (Schrödinger picture), the existence of these representation theorems implies that the time evolution of general empirical systems can be described by dynamical concepts borrowed from classical probability theory.