Zh. Kh. Murlieva

Peculiarities of dielectric properties of nanocrystalline bismuth ferrite

Results of the single-stage synthesis of nanocrystalline bismuth ferrite are presented. It is shown that the temperature and frequency dependences of dielectric properties of specimens produced by the cold compaction of the obtained powder substantially differ from those of microcrystalline bismuth ferrite produced using traditional ceramic technology.

Temperature dependence of electrical resistance of alloys caused by dynamic and static disorders

The results are presented of the experimental (in situ) measurements of electrical resistance and thermal expansion of electron compositions and their mechanical copper- and zinc-based mixtures, as well as of stainless steels within the temperature range of 300–1000 K. From the correlation analysis of these properties, the thermal deformation of the atomic lattice is shown to play the key role in formation of the electron scattering cross section. The role of the static disorder in the scattering cross section formation in alloys becomes noticeable for lattices with a high atom packing density.

YBa2Cu3O7–δ-based ceramic materials manufactured from nanopowders

The results of studying the structure and electrical resistance of nanostructured YBa2Cu3O7–δ-based superconducting ceramics of various density optimally saturated by oxygen and fabricated from nanopowders are given.

The correlation between electrical resistivity of metals and thermal deformation

A simple expression is given, which defines the unique correlation between phonon electrical resistance and the product of true coefficient of volumetric thermal expansion into temperature from ∼0 K to melting temperature. This expression is derived as a result of correlation analysis of experimental data on electrical resistivity and coefficient of thermal expansion of non-transition metals. This expression is validated within the phenomenological theory of condensed media.

A criterion for convection of elementary excitations in crystalline solids

A universal method is suggested that provides empirical estimates of the kinetic coefficients in the equations of quasiparticle transfer in crystalline structures. The method is based on a criterion for the onset of Landau convection and on an analysis of experimental data on the electric and thermal resistance and the thermal expansion coefficient for crystals with different types of interatomic bonds.

Effect of heat treatment on the structure and properties of a BiFeO3 nanopowder

This paper presents the results of an investigation of changes in the structure, magnetic, electrical, and thermal properties of a nanostructured bismuth ferrite powder prepared by the combustion of nitrateorganic precursors before and after heat treatment at temperatures of 500, 600, 700, and 800°C. It has been shown that there is a dependence of the magnetic properties on the dispersion of the particles. The specific features of the temperature and frequency dependences of the dielectric properties over wide ranges of frequencies and temperatures, as well as near the Néel temperature, have been considered.

Heat capacity of nanocrystalline bismuth ferrite

The heat capacity of the nanocrystalline multiferroic BiFeO3 was studied in a wide temperature interval of 150–800 K. It was found that the heat capacity nanocrystalline of bismuth ferrite in the temperature range of 350–570 K is noticeably larger than that of the microcrystalline sample. It was shown that the temperature dependence of the excess heat capacity is due to the manifestation of the Schottky effect for the three-level states appearing as a result of the structural distortions. The anomaly of the heat capacity typical for the phase transition, the manifestation of which depends on crystallite sizes, was discovered in the temperature range of T ≈ 720–750 K.

The electrical resistance of nickel and β-brass as a function of isobaric thermal deformation in ordered and disordered phases

Results are given of experimental investigations of electrical resistance and coefficient of thermal expansion of nickel and β-brass in the temperature range from 300 to 1050 K. It is found that the electrical resistivity of nickel and β-brass is directly proportional to relative thermal deformation in both ordered and disordered phases. It is demonstrated that a functional correlation exists between the respective order parameters and relative isobaric thermal deformation of lattices of these materials. Methods are given for estimating the contributions to the scattering of electrons by phonons and magnons, as well as by disturbances of atomic order in alloys.

Structure and Properties of Nanostructured YBa 2 Cu 3 O 7–δ , BiFeO 3 , and Fe 3 O 4

The development of new nanostructured materials based on YBa2Cu3O7–δ, BiFeO3, and Fe3O4 compounds is considered. The structure, morphology, and properties of these materials are studied. The possibilities of fabricating YBa2Cu3O7–δ ceramics with given densities from nanopowders in a single stage by an energy efficient method and growing superconducting films of the same composition on a silicon substrate (on a SiO2 layer) are demonstrated. The technique for fabricating BiFeO3 nanopowder, making it possible to obtain nanostructured ceramics without additional accompanied phases commonly forming during BiFeO3 synthesis is developed. Two methods of the single-stage synthesis of Fe3O4 nanopowder are presented: burning of nitrate-organic precursors and the electrochemical three-electrode method in which one of the electrodes, i.e., an anode containing scrap iron and slurry, is used as an expendable material.

The effect of high-enthalpy argon plasma flow on the structure and properties of YBa 2 Cu 3 O 7 – δ nanoceramics

The structure and electrical resistivity of YBa2Cu3O7 – δ-based nanostructured ceramics before and after exposure to the high-enthalpy argon plasma flow are investigated. It is demonstrated that the plasma-flow processing can strengthen the intergrain bonds in the surface layer of the ceramics and change its oxygen stoichiometry index.