A. Ya. Neiman

Intraphase chemical diffusion of water in Ba4Ca2Nb2O11

AbstractThe kinetics and mechanism of the water incorporation in binary perovskite (elpasolite) Ba4Ca2Nb2O11 are studied in the temperature interval 300–500°C at aH2O = 1 × 10−3 to 2.2 × 10−2. The product of hydration at these temperatures and values of aH2O is a solid solution of the composition Ba4Ca2Nb2O11·xH2O (x < 0.5). The process of interaction with water vapor is shown to be limited by the intraphase diffusion of hydrogen-and oxygen-containing species that enter the composition of H2O. Coefficients of chemical diffusion of water

The synthesis and properties of solid solutions based on Ba4Ca2Nb2O11

\tilde D_{H_2 O}

Electric properties of solid solutions based on strontium tantalate with perovskite-type structure. Protonic conductivity

are estimated from relaxation dependences of weight upon a stage-by-stage change of humidity loga H2O = −3.0 → −2.5 → −2.0 → −1.6. It is established that the coefficient of chemical diffusion of water for Ba4Ca2Nb2O11·xH2O at 0.1 < x < 0.5 insignificantly increases with increasing x. The chemical diffusion of water for the composition Ba4Ca2Nb2O11·0.35H2O is characterized by an activation energy of 0.38 eV. Given joint transfer of O2− and H+, the last value suggests that protons may exert an influence on the rate and energy of migration of oxygen. Possible forms of proton-containing species in the case of migration in experiments on chemical diffusion are discussed.

Surface diffusion, migration, and conjugated processes at heterophase interfaces between WO3 and MeWO4 (Me = Ca, Sr, Ba)

AbstractThe conductivity of the Ba4Ca2Nb2O11 phase and its solid solutions of the formulas Ba4.4Ca1.6Nb2O11 and Ba3.4Ca2.6Nb2O11 is studied as a function of the partial pressure of the water vapor at 2 × 10−2 − 3 × 10−5 atm (log

Electrochemistry of solid-phase reactions: Phase formation in the In2O3-WO3 system. Processes at the WO3|In2O3 and WO3|In6WO12 interfaces

P_{H_2 O}

Effect of size factor on mechanism of interaction between Al2O3 and Bi2O3 and conductivity of composite on their basis

= −1.7...−4.5) and temperatures of 400–600°C. A model, which is based on the model of structural oxygen vacancies, is proposed for the quasichemical description, providing an adequate explanation of the experimental dependences logσtot= f(log