Thermodynamics of oxygen in CaMnO3-δ

The experimental data for equilibrium oxygen content were used in order to extract increments of partial molar thermodynamic functions of oxygen with changes of oxygen stoichiometry in calcium manganite CaMnO3-δ. It is shown that along with the oxygen exchange reaction, thermal excitation of Mn4+ cations plays an important role in equilibration of charged manganese species that appear in response to the loss of oxygen at heating. The interrelation of partial molar enthalpy and entropy of oxygen with electron and ion defect formation parameters is obtained in approximation of the point defect model. The nearly linear changes of oxygen partial molar enthalpy are shown to directly reflect thermally driven changes in concentration of Mn3+ cations. © Springer-Verlag Berlin Heidelberg 2013

Electron transport in CaMnO3 - δ at elevated temperatures: A mobility analysis

The drift mobility of electron charge carriers in oxygen non-stoichiometric manganite CaMnO3 - δ was calculated by combining the total electrical conductivity and oxygen non-stoichiometry data at 700-950 ° C and oxygen partial pressure varying between 10-6 and 1 atm. The carrier concentration changes with pressure and temperature were obtained with the help of the earlier-developed defect model involving reactions of oxygen exchange and thermal excitation of manganese sites. The activation energy for mobility is found to increase with oxygen non-stoichiometry. High-temperature electron transport properties of the manganite CaMnO3 - δ can be explained in terms of activated jumps of n-type small polarons in adiabatic regime. The relatively small mobility of charge carriers is explained by strong localization of polarons on manganese sites. © 2013 Springer-Verlag Berlin Heidelberg

Mechanisms of hopping conductivity in weakly doped La₁₋ₓВaₓMnO₃

The localization radius of the charge carriers, a, has different constant values within the temperature intervals where δ(T) ~ T½. With further decrease of T, a increases according to the law expected for small lattice polaronsyesBelgorod State Universit

Outline of a Self-Reflecting Theory

We call an interpreted theory self-reflecting iff this theory is its own meta-theory, which means that it describes its own syntax, semantics, and interpretation. We construct an example of such a theory, which we call reflectica. At the same time, reflectica is an intensional system much simpler than well known intensional logics

The complement of a σ-compact subset of a space with a π-tree also has a π-tree

We prove that the complement of a σ-compact subset of a topological space that has a π-tree also has a π-tree. To do this, we construct the foliage hybrid operation, which deals with foliage trees (that is, set-theoretic trees with a ‘leaf’ at each node). Then using this operation we modify a π-tree of a space and get a π-tree for its subspace. © 2017 Elsevier B.V