Valency

About: Valency is a research topic. Over the lifetime, 1632 publications have been published within this topic receiving 26141 citations.

Mössbauer studies of structural properties and electrochemical characteristics of LiFePO 4

Abstract: The valency state and local coordination of Fe ions of four industrial samples and a sample of cathodic materials for recharcheable lithium ion batteries obtained using an original technology of St. Petersburg State Technological Institute (Technological University) were studied using the Mossbauer effect on the 57Fe isotope. It was found that the main valency state for more than 90% of iron ions was Fe2+. The values of isomer shift δ = 0.96–0.98 mm/s and quadrupole splitting σ = 2.88–2.93 mm/s for Fe2+ ions coincide with the values for compounds with the structure of olivine LiFePO4 and occupy positions in highly distorted FeO6 octahedrons. Fe3+ ions are in octahedral and/or tetrahedral local positions.

Density of states in the gap, connected with dipole defects in the chalcogenide vitreous semiconductors

Abstract: Any deviations of the structure of glassy semiconductors from the structure of the appropriate crystals result in the occurrence of states in the gap. In chalcogenide glassy semiconductors the distribution of states in the gap exhibits features specific to discrete [1-3] spectra, and quasi-continuous one [4-6]. As follows from the analysis of the dependence of mobility and conductivity on the electrical field in As2Se3 the existence of smooth distribution upon energy of the states near to edges of a valence band is possible. From the analysis of the hole mobility it results the existence of energy levels situated at 0.45 eV from the edge of the valency band. The nature of these states is not quite clear. It is supposed that local defects, which are related to the changes of chemical bond and coordination, form, as a rule, states, deeply laying in a gap, with enough precisely fixed energy forming a discrete spectrum. In turn, fluctuation in bond lengts, valency and torsion angles results in the formation of gap states, whose density N (E) falls down deep into gap and is characterized by a quasicontinuous spectrum. However, the local defect, too, in case its geometry is accompanied by significant fluctuations of potential, can form group of the states, distributed enough deep in a gap, and near to the edges of a valence band and conductivity, thus forming a spectrum.

High temperature near IR spectral properties and thermal radiation conductivity of (un)colored silicate glass melts

Abstract: Using an emittance technique with fast CO2 laser heating of glass samples, the high temperature absorption spectra in the near IR region of ultrapure and colored (Co-, Cu-, Mn- and Ni-doped) glasses are measured. The effects of higher glass temperatures on these absorption spectra are explained in the framework of the ligand field theory. Thus, the temperature dependent absorption bands of the above transition metal ions are assigned to electronic transitions between the ligand field energy levels of these ions. In particular, spectral shifts, spectral broadening and changes in absorption strength are ascribed to changes in the structural symmetry of the ionic sites in the glass matrix and to changes of the ligand field strength at increasing temperatures. Besides, the temperature dependent Rosseland mean absorption of the sulfate fined soda lime silicate glass melts, colored with the above transition metal ions, are derived from the absorption spectra. Combining all the data, semi-empirical correlations can be derived, which predict the Rosseland thermal radiation properties as a function of glass temperature and of glass redox chemistry, where the latter property involves the temperature dependent concentration of the specific valency of the coloring ions, determined independently by a Gibbs minimization redox calculation tool. This article is protected by copyright. All rights reserved

How do middle voice markers and valency reducing constructions interact? Typological tendencies and diachronic considerations

Abstract: Abstract Middle voice markers are highly polyfunctional items that, among other things, also perform a range of valency-changing operations such as anticausativization and reflexivization. Typological research has shown that individual markers display a great deal of variation with respect to their inventory of functions. Explaining this variation remains a key question that a comprehensive typology of middle markers needs to address. We now know that only a sub-set of the possible polyfunctionality patterns is actually attested and that existing patterns often represent the result of specific grammaticalization processes. In this paper, I explore yet another possible factor, that is, the interaction between middle markers and other valency-changing constructions within the same language. Based on a study of 129 middle-marking languages, I single out two recurrent patterns, that is, complementarity and competition, and argue that their study offers crucial insights in explaining the synchronic polyfunctionality of middle markers.