Search results for "VS."

Dielectric investigation of lead‐free perovskite strontium titanate with 25% bismuth ceramics

2009

In this work lead-free 0.75SrTiO3-0.25BiTiO3 ceramics have been investigated in broad frequency range. Obtained results showed pronounced dispersion below room temperature typical for the dipolar glasses. The calculated relaxation time distribution function broadens toward longest relaxation times part on cooling. The obtained most probable relaxation time diverges according to the Vogel-Fulcher relationship with the following parameters: dipole activation energy EA=2123 K, glassy state temperature T0=52.7 K, shortest relaxation time, referring to dipole relaxations at very high temperatures, τ0=2.1·10–14 s. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Comparative study of [001] surface relaxations of perovskite titanates

1998

Surface relaxations of the cubic perovskite SrTiO and BaTiO crystals have been studied in the framework of the shell model. The 33 positions of atoms in several surface layers embedded into the electrostatic field of the remainder of the crystal were calculated. Ti 4q , Sr 2q ,B a 2q and O 2y ions in six near-surface layers are displaced differently from their crystalline sites. Such effects create the so-called surface rumpling, a dipole moment and the electric field in the near-surface region. Calculated atomic displacements were compared with the LEED experimental data and showed good agreement. Our simulations have demonstrated that the cubic perovskite SrTiO crystals 3 reveal surface p…

Viable Systems Approach and Consumer Culture Theory: A Conceptual Framework

2013

The aim of this study is to depict the relational dynamics between the firm/ brand and the individual/consumer or communities of consumers. To this aim we propose a conceptual framework, integrating the viable systems approach (VSA) with consumer culture theory (CCT), which considers the individual as an active co-maker of the product/brand (‘prosumer’). The VSA view of the firm overcomes the limitations of CCT research, which is mainly focused on the individual, giving little consideration to the other actors in the context. Among the different approaches under the umbrella of viable systems we chose the VSA because of its emphasis on the analysis of the systemic external relations with th…

Regular and singular pulse and front solutions and possible isochronous behavior in the Extended-Reduced Ostrovsky Equation: Phase-plane, multi-infin…

2016

In this paper we employ three recent analytical approaches to investigate several classes of traveling wave solutions of the so-called extended-reduced Ostrovsky Equation (exROE). A recent extension of phase-plane analysis is first employed to show the existence of breaking kink wave solutions and smooth periodic wave (compacton) solutions. Next, smooth traveling waves are derived using a recent technique to derive convergent multi-infinite series solutions for the homoclinic orbits of the traveling-wave equations for the exROE equation. These correspond to pulse solutions respectively of the original PDEs. We perform many numerical tests in different parameter regime to pinpoint real saddl…

Segregation of copper oxide on calcium copper titanate surface induced by Graphene Oxide for Water splitting applications

2020

Abstract Photoelectrochemical cells (PEC) are promising devices for hydrogen production via sunlight energy. One of the important challenges in this area is to design photoactive electrodes able to absorb visible light. A good photoelectrochemical behavior depends on the presence of surface active sites to photogenerate current at the lower possible potential for water splitting. Recent investigations in this field are focusing on perovskite materials such as CaCu3Ti4O12 (CCTO) as visible light active electrode due its outstanding structure in which CCTO encloses in its structure a visible light absorbance component (CuO). The presence CuO on the material surface is mainly responsible for t…

Local structure of A-atom in ABO3 perovskites studies by RMC-EXAFS

2020

The measurements of Sr K-edge XAFS were performed under the approval of Proposal No. 97G042 of Photon Factory (KEK) and partially supported by the Research Grants of Hirosaki University. This work was supported by Bruce Ravel providing data for BTO. Boby Joseph acknowledges IISc Bangalore and ICTP Trieste for financial support through the award of the IISc-ICTP fellowship.

«CHI LASCIA LA STRADA VECCHIA PER LA NUOVA, …» PERCHÉ UNA RIFORMA DEI DELITTI DI CORRUZIONE NON DOVREBBE ABBANDONARE IL MODELLO MERCANTILE

2014

Similarity Solutions and Collapse in the Attractive Gross-Pitaevskii Equation

2000

We analyse a generalised Gross-Pitaevskii equation involving a paraboloidal trap potential in $D$ space dimensions and generalised to a nonlinearity of order $2n+1$. For {\em attractive} coupling constants collapse of the particle density occurs for $Dn\ge 2$ and typically to a $\delta$-function centered at the origin of the trap. By introducing a new dynamical variable for the spherically symmetric solutions we show that all such solutions are self-similar close to the center of the trap. Exact self-similar solutions occur if, and only if, $Dn=2$, and for this case of $Dn=2$ we exhibit an exact but rather special D=1 analytical self-similar solution collapsing to a $\delta$-function which …

Génétique textuelle : approches croisées et études de cas

2023

"Génétique textuelle : approches croisées et études de cas" confronte, sur des oeuvres diverses, les acquis de la critique génétique telle qu'elle s'est développée et enrichie particulièrement en France depuis sa fondation d'obédience structuraliste et à distance des analyses issues de la tradition philologique italienne dans le fil de la « critique des variantes ». D'autre part, les différents articles offrent, à côté de corpus manuscrits déjà bien étudiés tels que Flaubert et Proust, des investigations sur des auteurs qui ne sont que rarement analysés dans le cadre d'études de genèse, qu'il s'agisse de Butor - dont on présente ici des manuscrits inédits - Némirovsky, Malraux ou Pavese.

<title>Large-scale first-principles calculations of Fe-doped SrTiO<formula><inf><roman>3</roman></inf></formul…

2003

The energy level positions in the optical gap and atomic geometry for the Fe4+ impurity substituting for a host Ti atom in SrTiO3 are calculated using the Unrestricted Hartree-Fock (UHF) method and supercells containing up to 320 atoms. In agreement with experiment, the high spin (S = 2) state is much lower in energy than the zero-spin state. The energy level positions strongly depend on the asymmetric displacements of six nearest O ions which is a combination of the Jahn-Teller and breathing modes. A considerable covalent bonding between the Fe ion and four nearest O ions takes place. We predict a strong dependence of optical absorption energies on the crystal compression or internal tensi…