M. V. Morozova

Synthesis, region of existence, structural characteristics, and conductivity of BI(CR, FE)VOX solid solutions

The results of our studies of solid solutions of the general composition Bi4V2 − xFex/2Crx/2O11 − δ are presented. The crystal-chemical parameters of different polymorphic modifications of BIMEVOX were determined. The particle size distribution was determined by laser diffraction and optical microscopy. The surface of sintered preforms was studied by scanning electron microscopy. The conductivity of sintered poly-crystalline samples as a function of temperature and composition was studied by impedance spectroscopy. The conductivity was depends on the procedure for the synthesis of solid solutions. The most promising compositions were revealed.

Some features of the preparation, structure, and properties of BICUTIVOX

This work continues the search for optimal preparation methods and studies of structural and transport characteristics of BICUTIVOX solid solutions of the general composition Bi4V2 − xCux/2Tix/2O11 − δ (x = 0.0−0.35).

Structural and thermal stability of BIMEVOX oxygen semiconductors

The results on the structural and thermal stability of different modifications of solid solutions Bi4V2 − xFexO11 − δ (BIFEVOX), where x = 0.05–0.6, and Bi4V2 − xCux/2Tix/2O11 − δ (BICUTIVOX), where x = 0.025–0.50, are shown. The stability is assessed by varying the thermodynamic parameters of the medium and also the time parameters with the use of modern methods, namely, the high-temperature X-ray diffraction analysis, the differential scanning calorimetry, and the dilatometry. The γ-modification of BIFEVOX is shown to be stable in a wide range of temperatures and oxygen partial pressures.

Кристаллическая структура и проводимость висмут - содержащих сложных оксидов Е. С. Буянова, Ю. В. Емельянова, М. В. Морозова, З. А. Михайловская, О. С. Каймиева, В. М. Жуковский, С. А. Петрова

The kinetics of surface reactions in one-dimensional and radial (two-dimensional) distribution of diffusant MoO 3 (WO 3 ) on the surface of the substrate MeO (Me is Cd, Ni, Pb, Mn, Cu) were investigated. A kinetic equation satisfactorily describes the rate of surface reactions in the case of radial distribution of diffusant on the substrate. It’s found that when the radial distribution of diffusant the growth of layer on the substrate surface eventually slows down and stops almost completely, due to the outflow of the diffusant deeps into the substrate. When the one-dimensional distribution of diffusant the surface interaction is not slowed down and does not stop at an arbitrarily large times.In the paper, a comprehensive systematic study of different classes of bismuth containing oxide compounds was carried out. The relationship between composition, temperature and concentration regions of existence of stable, specific structure and properties of solid solutions on the basis of vanadates, molybdates, niobates and bismuth was found. The general regularities of synthesis of solid solutions with different variants of solid-phase and soluble methods were determined. On this basis, the optimal conditions for obtaining single-phase materials were formulated. For the first time the temperature and concentration boundaries of the regions of homogeneity and areas of stable existence of polymorphic modifications of solid solutions were defined and/or refined. The structural parameters of the synthesized phases were determined. By the method of electrochemical impedance spectroscopy the nature and features of impedance spectra, the temperature and concentration dependences of electrical conductivity of ceramic materials based on bismuth containing complex oxides were identified.

Impedance spectroscopy of oxide ceramics with overall composition of Bi4V2 − xMexO11 − δ

The paper presents a generalization for some studies of conducting properties of ceramics based on solid solutions with the general composition of Bi4V2 − xMexO11 − δ of the BIMEVOX family obtained using the impedance spectroscopy method. The regularities of the impedance spectra and typical complex plane plots are considered and the corresponding equivalent circuits are analyzed.

Synthesis processes and transport properties of solid solutions in the Bi2O3-GeO2-V2O5 system

The results of studies of solid solutions with the overall composition of Bi4V2 − xGexO11 − δ and Bi4Ge3 − xVxO12 + δ are presented. The process of phase formation are studied during the synthesis of solid solution using the ceramic method and through liquid precursors. Crystallochemical parameters of the obtained compounds are determined. The size distribution of the particles is studied. Conductivity of annealed of polycrystalline samples as a function of temperature and composition is studied using the impedance spectroscopy method. The shape of impedance complex plane plots of the samples obtained in different ways is studied and analyzed.