The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-xGd xFeO3 were carried out over a wide concentration range x = 0.00-0.50.

Keywords: multiferroic crystal structure, grain structure, dielectric properties

The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хNdxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

Keywords: multiferroic crystal structure, grain structure, dielectric properties

The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хSmxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

Keywords: multiferroic crystal structure, grain structure, dielectric properties

The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-x LaxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

Keywords: multiferroic crystal structure, grain structure, dielectric properties

The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хPrxFeO3were carried out over a wide concentration range x = 0.00-0.50.

Keywords: multiferroic crystal structure, grain structure, dielectric properties

The manuscript presents results of a study ferroelectric ceramic metaniobate lithium (PCR-61) which containing Li2O, Nb2O5 and CaO in the fallowing ratio, mass. % Li2O 10,03-10,10; Nb2O5 89,22-89,87; CaO 0,03-0,75. The most effective was the offset component in alcohol and air environments, which providing sufficiently high rate of sintering, the formation on their base high density ceramic with the most perfect crystal structure and microstructure of the equilibrium. Using the foregoing results the solid phase material was prepared by one-stage synthesis (SPS) for Tsint.1 = 820℃, τ = 5h. with followed by sintering by conventional ceramic technology (CCT) (without pressure) at a temperature Ts. = 1150℃, τ = 2h. After machining, the samples were polarized ("oil" polarization). The promising method SPS + CCT was presented. Material based on piezoelectric ceramics metaniobate lithium (PCR 61) was obtained by the SPS + CCT, close to the parameters of hot-pressed (HP) samples and can be used in electrical devices under the influence of ultra-high temperatures. The effectiveness of heterovalent modification as a method of directional changes in the properties of lithium metaniobate was shown.

Keywords: ferroelectric ceramics, metaniobates lithium, solid-phase synthesis, conventional ceramic technology, the electrical properties, high temperature technology

In this work we continue the study of ferroelectric compositions of different composition – basics of functional materials piezo technical destination. Considered are solid solutions (TR) binary system (1-x) PbZrO3 – x PbTiO3 (PZT), up to the present time remaining as base of almost all commercially available functional materials. Studied the impact of technological regimes on the properties of solid solutions with 0.135 ≤ x ≤ 0.145, 0.16 ≤ x ≤ 0.18, 0.37 ≤ x ≤ 0.58, 0.75 ≤ x ≤ 0.77, 0.795 ≤ x ≤ 0.805, the research concentration step Δx = 0.0025. The sintering temperature was varied from 1200 °C to 1240 °C, the duration of the extracts 2 and 3 hours. It is established that the structural parameters remain almost constant under variations of conditions in process their production in all ranges (rhombohedral, tetragonal and morphotropic) of the concentrations, and the change of relative dielectric permittivity of unpolarized samples is not more than (10÷12) %. It was shown that the study of solid solutions of multicomponent systems on the basis of lead zirconate titanate is possible with the minimal concentration of the step ∆x = 0.25 mol.%. Application of the considered techniques in the fabrication of functional materials for various purposes provides high reproducibility of their parameters. Obtained results can be useful for development of new ferro-piezoelectric materials on the basis of other complex oxides.

Keywords: solid solution, lead zirconate titanate, technology, crystal structure, dielectric permittivity

This paper proposes criteria for the optimal choice of a database management system (DBMS), based on the requirements to this system. Empirically assessed criteria and method of analytic hierarchy process for decision making were used to carry out the comparative analysis of several DBMSs, implementing relation data model and having similar functionalities. The obtained matrixes of pair-wise comparison are examined for concurrence by calculating indices described in the article. As a result, the database management system for the own project is rationally chosen.

Keywords: DBMS, method of analytic hierarchy process, criteria, matrixes of pair-wise

The method of laser therapy is based on synchronization of phases of inflow (anacrotism) and outflow of blood (catacrotism) in the field of the pathological center with phases of a being narrowed and extending laser spot on a projection of this pathological center. It is supposed that being narrowed on a projection of the pathological center the spot of laser light stimulates blood inflow to the spot center, and the extending spot of a laser beam – activates blood outflow in the direction from the spot center to its periphery. The developed technique of the automated correction of hemodynamic frustration consists in pilot signal formation (in charge of the power and laser positioning) for the laser machine on the basis of a difference between a reference rheogram and a rheogram of the patient (a body site) in real time.The offered technique has to allow to use more efficiently methods of laser therapy at treatment of violations of a blood-groove. The technique is calculated on the basis of numerical experiment by means of methods of mathematical model operation.In the real experiment the question of synchronization of the reference and measured signal is considered solved though this task represents a subject of separate researches.The received pilot signal can be in real time transformed to the current signal operating positioning and laser power.The method gives the chance of an operating control of a condition of the patient and blood-groove diagnostics to, in time and after a session of laser therapy. Development provides possibility of adaptive individual correction and optimization of parameters of influence during a session and a course of treatment.

Keywords: laser, therapy, technique, rheogram, diagnostics, blood-groove, management, signal

The combination of the unique, abnormal properties shown by oxidic systems with structure of spinel on the basis of transitional elements chromites draws attention of researchers for many years. Some systems on the basis of transitional elements chromites (for example, nickel and copper chromites) have critical elements (multicritical points, lines of phase transitions of the second sort, etc.) on the phase chart. Near these elements of the phase chart materials possess unique chemical and physical properties. Therefore development methods of receiving and research of phase forming and properties in NIO-CoO-CuO-Cr2O3 system represent fundamental and practical interest for chemistry and technology of inorganic substances. In this work processes of spinel structure formation in system 0,6 NiCr2O4 – 0,2 CoCr2O4 – 0,2 CuCr2O4 from crystal chemistry positions are considered. Formation of two solid solutions on the basis of nickel (II) chromite – with structure of cubic spinel and with tetragonal distorted structure is established. The influence of cooperative Yahn-Teller effect on processes of a spinel forming and on stabilizing impact of chloride of potassium on process of education of  two spinel solid solutions is suggested. Influence of a power factor of cation stabilization in knots of a crystal lattice as one of the important factor in reaction of spinel structure formation is considered.

Keywords: spinels, chromites of transitional elements, Jahn-Teller effect

Information about authors of issue (№1 2014)

Keywords: authors

The results of computational experiments to determine the characteristics of the porous piezoelectric ceramics based on the methodology, including the effective modules method, simulations of representative volumes on a simple random method and the method of Witten-Sander, finite element method to solve static piezoelectric problems for heterogeneous composite media and the accounting of inhomogeneous polarization near the pores are presented. A comparison of the results of computer simulation with the known experimental data for the porous material PZT-4 and its analogs is realized. It is concluded that the accounting of inhomogeneous polarization in the vicinity of porous provide the better agreement between numerical results and large number of known experimental data. Thus, for most effective constants the smallest errors are obtained for a representative volume of the porous piezoelectric material, constructed by Witten-Sander method.

Keywords: piezocomposite, porous piezoelectric ceramics, inhomogeneous polarization, mathematical modelling, models of representative volumes, finite element method, effective moduli

  The requirements to be met by a data acquisition system in terms of each of the problems to be solved. Presented electric concept developed biopotential amplifier with a total gain of 2000. The theoretical model of the spectrum of RR intervals and changes depending on the running processes. The analysis revealed that the resulting spectrum satisfies the conditions considered in the theoretical model, and can be further analyzed with fractal characteristics.

Keywords: Instrumental amplifier, biopotential, fractal index

Briefly discussed the theoretical model of the spectrum of RR intervals and its changes depending on the processes taking place. Made a device for measuring cardiointervalogramms (CIG). Obtained from the renting of data, of varying duration and frequency shall be recorded for further processing. The analysis revealed that the resulting spectrum satisfies the conditions considered in the theoretical model, and can be further analyzed with fractal characteristics. Such an analysis is of great importance in the diagnosis of the patient directly to the duration of the therapeutic procedure for the optimization of both time and intensity exerted influence.

Keywords: CIG; fractal series; the spectrum of RR intervals

 Theoretical model of anomalous electron emission has built for an soft x-ray irradiation of  surface elektrets, explaining the different character of correlation between energy and emission intensity of ferroelectric  solid solution PbTiO3 - CaTiO3 and nonferroelectric  ceramics CaTiO3.  Shown that  due electret surface irradiation the  Schottky area is  depleted by nonequilibrium charge carriers.

Keywords: Emission, electret, ferroelectricity, Schottky area