Towards a physical lattice model for the atom and implications for high-Tc superconductivity

2017 ◽  
Vol 31 (25) ◽  
pp. 1745009
Author(s):  
Jean-Francois Geneste ◽  
Jenny Darja Vinko
Keyword(s):  
Mathematical Model ◽  
Atomic Nucleus ◽  
Vapor Phase ◽  
Lattice Model ◽  
High Temperature Superconductivity ◽  
Temperature Decrease ◽  
High Tc ◽  
Reciprocal Influence ◽  
Global View ◽  
Very High

Starting from Cook’s model [D. N. Cook, Models of the Atomic Nucleus (Springer, Berlin, 2006)], we proposed a non-Archimedean approach to show that we can transform his purely mathematical model into a physical one. In the first stage, we kept the f.c.c. lattice model surrounded by a vapor phase from which we can only extract “symmetric” entities (quantons?) which are the electrons. This in our opinion gives a much better global view of what the atom could be. When assembling the nuclei into a lattice, there is reciprocal influence between the vapor phase and the lattice. Consequently, superconductivity occurs when temperature decrease brings to freezing the vapor phase and when the “crystallization” of the vapor phase gives some symmetric tiling of the volume around the lattice, thanks to Curie’s theorem. Looking for high temperature superconductivity therefore is equivalent to finding symmetric crystallization of the vapor phase. In that sense this pleads for the use of heterogeneous materials in the “crystal grid” and the case being play with impurities. We do not see any limit, thanks to our model, for high and even very high temperatures for superconductivity.

High-Tc Superconductors Under Very High Pressure

1991 ◽  
pp. 399-417
Author(s):  
Rinke J. Wijngaarden ◽  
J. J. Scholtz ◽  
E. N. van Eenige ◽  
R. Griessen
Keyword(s):  
High Pressure ◽  
High Tc Superconductors ◽  
High Tc ◽  
Very High

scholarly journals The Research on the Visual Obstacle-Avoidance Optimization in Robots Control

2013 ◽  
Vol 756-759 ◽  
pp. 372-375
Author(s):  
Hong Bin Tian
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Obstacle Avoidance ◽  
Visual Information ◽  
Structural Model ◽  
Three Dimension ◽  
Coordination Control ◽  
Dimension Space ◽  
The Mathematical Model ◽  
Very High

In order to increase the movement capability of the robotic visual system in three-dimension space, the paper designs an obstacle-avoidance algorithm based on robotic movement visual by effectively processing the visual information colleted by the robotics. This paper establishes a structural model of coordination control system. The obstacles can be effectively identified and avoided by the obstacle-avoidance theory in the robotics coordination operation. The mathematical model of the obstacle-avoidance algorithm can predict the locations of the obstacles. The experiment proves the proposed algorithm can avoid the obstacles in three-dimension space and the accuracy is very high.

scholarly journals Potential high-Tc superconducting lanthanum and yttrium hydrides at high pressure

2017 ◽  
Vol 114 (27) ◽  
pp. 6990-6995 ◽  
Author(s):  
Hanyu Liu ◽  
Ivan I. Naumov ◽  
Roald Hoffmann ◽  
N. W. Ashcroft ◽  
Russell J. Hemley
Keyword(s):  
Group Structure ◽  
High Temperature Superconductors ◽  
Face Centered Cubic ◽  
Superconducting Transition ◽  
High Tc ◽  
Structure Search ◽  
Systematic Structure ◽  
Face Centered ◽  
Fcc Structure ◽  
Very High

A systematic structure search in the La–H and Y–H systems under pressure reveals some hydrogen-rich structures with intriguing electronic properties. For example, LaH10 is found to adopt a sodalite-like face-centered cubic (fcc) structure, stable above 200 GPa, and LaH8 a C2/m space group structure. Phonon calculations indicate both are dynamically stable; electron phonon calculations coupled to Bardeen–Cooper–Schrieffer (BCS) arguments indicate they might be high-Tc superconductors. In particular, the superconducting transition temperature Tc calculated for LaH10 is 274–286 K at 210 GPa. Similar calculations for the Y–H system predict stability of the sodalite-like fcc YH10 and a Tc above room temperature, reaching 305–326 K at 250 GPa. The study suggests that dense hydrides consisting of these and related hydrogen polyhedral networks may represent new classes of potential very high-temperature superconductors.

Granular Aspects of High Tc Superconductivity

1990 ◽  
Vol 195 ◽  
Author(s):  
Guy Deutscher
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
Original Publication ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Bulk Ceramic ◽  
Ceramic Samples ◽  
Granular Superconductors

ABSTRACTAs Bednorz and Muller noted in their original publication reporting on the discovery of high temperature superconductivity, their oxides present many of the features of granular superconductors. This behavior was first primarily ascribed to poor connectivity of the grains in the bulk ceramic samples. but later studies have pointed out to more fundamental reasons for these similarities. We will discuss them after first reviewing the well established properties of low Tc granular superconductors.

scholarly journals Mathematical Model of Rotary Machined Helical Surfaces

2021 ◽  
Vol 346 ◽  
pp. 01038
Author(s):  
Mikhail Popov
Keyword(s):  
Mathematical Model ◽  
Temperature Decrease ◽  
Mathematical Foundation ◽  
Rotary Tool ◽  
High Durability ◽  
High Temperature Alloys ◽  
Cutting Zone ◽  
Rotary Cutting ◽  
Mathematical Calculation ◽  
Laminated Materials

The rotary cutting method of materials has a number of advantages over the existing traditional cutting methods, e.g. temperature decrease in the cutting zone, also noncumulative blade wear. Due to its high durability, the rotary tool allows processing hardened and difficult-to-machine materials, high-temperature alloys, as well as composite and laminated materials. However, this machining method is usually not applied for machining various shaped surfaces, which is mainly due to the lack of mathematical calculation of the resulting profiles, and the absence of a wide variety of methods for rotary tools installation. The article discusses the mathematical foundation of the resulting profile when processing helical surfaces when processing the flanks of rotary tools.

scholarly journals APPLICATION OF MATHEMATICAL PLANNING OF THE EXPERIMENT IN THE CHOOSING THE OPTIMUM CONDITIONS OF THE VAPOR-PHASE GAS-CHROMATOGRAPHIC DETERMINATION OF FORMALDEHYDE IN THE URINE

2018 ◽  
Vol 97 (10) ◽  
pp. 985-989 ◽  
Author(s):  
Аnton N. Alekseenko ◽  
O. M. Zhurba
Keyword(s):  
Mathematical Model ◽  
Vapor Phase ◽  
Statistical Processing ◽  
Analytical Signal ◽  
Heating Time ◽  
Gas Extraction ◽  
Optimal Conditions ◽  
Steep Ascent ◽  
The Mathematical Model

Introduction. There was substantiated a method for the determination of formaldehyde by vapor-phase gas chromatography by the use of derivatizing reagent o-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine. Material and methods. Formaldehyde in urine was derivatized to o-pentafluorobenzyloxime and recovered to the vapor phase by heating the urine sample with o-(2,3,4,5,6-pentafluorbenzyl)hydroxylamine in a sealed vial. Gas-chromatographic analysis of the vapor-air phase was performed in a mode of the temperature gradient on a capillary column HP-5 with a flame ionization detector. Identification of the analyte in the form of the derivative-o- pentafluorobenzyloxime of formaldehyde was carried out according to the absolute retention time, which was established by comparing the chromatograms of model formaldehyde mixtures in the urine of different concentrations. Results. The optimal conditions for gas extraction are selected using mathematical experimental planning. The most important factors of gas extraction in the vapor-phase analysis are the temperature and time of the establishment of the interphase equilibrium with heating. From the experimentally obtained curves of the analytical signal on the temperature and the heating time, the zero level and the interval of variation of these factors are chosen. A matrix for planning a 2-factor experiment was constructed. The coefficients of the mathematical model are determined. There was carried out statistical processing of the experimental data, which was reduced to the estimation of the reproducibility of the optimization parameter and to the evaluation of the significance of the coefficient of the mathematical model. The adequacy of the mathematical model was evaluated, its interpretation was carried out. Discussion. The peak area of the analyte increases with the elevating the temperature and heating time, due to an increase in the analyte concentration in the vapor phase. Moreover, the heating time makes a greater contribution to the formation of the analytical signal than the temperature. The step of motion along the gradient was calculated and the experiments of steep ascent were carried out. Conclusion. According to the results of the steep ascent experiments, the optimal conditions for the gas extraction of formaldehyde in the form of a derivative were chosen.

Electron-Doped High Tc Superconductors

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 60-67 ◽  
Author(s):  
M. Brian Maple
Keyword(s):  
High Temperature ◽  
High Temperature Superconductivity ◽  
High Temperature Superconductors ◽  
Building Blocks ◽  
The United States ◽  
Charge Carriers ◽  
Critical Temperatures ◽  
High Tc ◽  
Prevailing View ◽  
Identical Crystal

Since the discovery of high temperature superconductivity in layered copper-oxide compounds in the latter part of 1986, an enormous amount of research has been carried out on these remarkable materials. Prior to 1989, the prevailing view was that the charge carriers responsible for superconductivity in these materials were holes that move through conducting CuO2 planes. The CuO2 planes are the basic building blocks of the crystal structures of all the presently known oxides with superconducting critical temperatures Tc greater than ~30 K. Recently, new superconducting materials have been discovered in Japan and the United States in which the charge carriers involved in the superconductivity appear to be electrons, rather than holes, that reside within the conducting CuO2 planes. These findings could have important implications regarding viable theories of high temperature superconductivity as well as strategies for finding new high temperature superconductors.The new electron-doped materials have the chemical formula Ln2-xMxCuO4-y and exhibit superconductivity with superconducting critical temperatures Tc as high as ~25 K for x ≍ 0.15 and y ≍ 0.02. Superconductivity has been discovered for M = Ce and Ln = Pr, Nd, Sm, and Eu, and for M = Th and Ln = Pr, Nd, and Sm. A related compound with the identical crystal structure, Nd2CuO4-x-y Fx, has also been found to display superconductivity withTc ≍ 25 K. Recently, it has been observed that superconductivity with Tc ≍ 25 K can even be induced in nonsuperconducting Nd2-xCexCuO4-y compounds by substituting Ga or In for Cu. Thus, it appears that the CuO2 planes can be doped with electrons, rendering the Ln2CuO4-y parent compounds metallic and superconducting, by substituting electron donor elements at sites within, as well as outside, the CuO2 planes; i.e., by substituting (1) Ce4+ or Th4+ ions for Ln3+ ions; (2) F1- ions for O2- ions; and (3) Ga3+ or In3+ ions for Cu2+ ions.

scholarly journals Vibronic Mechanism of High Tc Superconductivity

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3266-3270 ◽  
Author(s):  
M. Tachiki ◽  
T. Egami ◽  
M. Machida
Keyword(s):  
Transition Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Attractive Interaction ◽  
Low Frequencies ◽  
High Tc ◽  
Eliashberg Theory ◽  
Bond Stretching ◽  
Vibronic Effect

When phonons strongly mix with electron charge fluctuations with low frequencies, the phonon mediated attractive interaction between electrons is strongly enhanced. The occurrence of the mixing has been indicated by the neutron scattering experimental results that the dispersion of the in-plane Cu–O bond-stretching mode in the high Tc cuprate superconductors is strongly softened near the zone boundary. We propose that the phonon mediated attractive interaction strongly enhanced by the vibronic effect can form a basis for the phonon mechanism of high temperature superconductivity. With the Eliashberg theory and with the electronic structure determined by ARPES and the electronic dielectric function obtained by the softened dispersion of the in-pane Cu–O stretching mode, we calculated the transition temperature and the order parameter at the transition temperature. The order parameter is of the d(x2-y2) symmetry and the transition temperature is well in excess of 100 K.

Sign in / Sign up

Export Citation Format

Share Document