The electrophysical and mechanical properties of a piezoceramic material based on CTS are investigated. A number of features in the behavior of the electrophysical properties of the material in the temperature range located significantly below the low-frequency (1 kHz) maximum of the dielectric constant T_m = 160℃ have been revealed. The obtained results indicate the proximity of the studied material to ferroelectric relaxors, in particular, the low coercive field E_c~5 kVcmcm, the significant dependence of T_m on the frequency and amplitude of the measuring field, as well as the behavior of the velocity of longitudinal ultrasonic waves in this ceramic. It is shown that the elastic properties of this material are very close to ferroelectric relaxors, having a high malleability in a very wide temperature range. At the same time, the squareness of the polarization loops at relatively low temperatures indicates the manifestation of the classical properties of the ferroelectric during the polarization switching processes, and not the "freezing" processes characteristic of ferroelectric relaxors. From the results obtained, it can be established that this composition will be promising for use in the actuators of adaptive optics systems and precision positioning devices due to the high values of piezomodules.
Keywords: PZT system, ferroalloy ceramics, dispersion, polarization, elastic properties, blurred phase transitions, curie temperature, depolarization temperature, ferroelectric relaxor, rhombohedral phase, tetragonal phase
Piezoceramics based on the lead zirconate-titanate (PZT) system is the basis of most transducers operating on the piezoelectric effect and are used in various electronic devices operating in the sections of electrical and hydroacoustics, ultrasonic technology, etc. In turn, piezoceramic materials created in the last century have substantially exhausted their potential for use in modern devices, and it is rather difficult to develop new compositions and is not economically efficient. In connection with the above, an urgent task is to find modern ways to increase the parameters of piezoceramic materials.
Keywords: piezoceramics, piezophase, piezomaterial, ceramic technology, microstructure
This article presents the results of a parameters study on a piezoelectric flexible transducer of a beam type. The analysis was performed by the finite element method using the ANSYS Multiphysics software package. It is shown that there are optimal parameters ratios of the structural elements of the transducer under study for which it is the most effective
Keywords: bending-type piezoelectric transducer, piezoelectric element, elastic plate, resonance frequency, conversion coefficient, Electromechanical coupling coefficient
The loops of the dielectric hysteresis of a soft ceramics based on PZT with Curie temperature TC=210℃ are investigated. The studies were carried out at a frequency of 50 Hz in two modes. In the first of them, the field was switched on by 0.07 seconds, in the second - it operated continuously. The amplitude of the field E_m varied from 2.5 to 25 kV / cm and switched stepwise with an interval of 15 minutes. The coercive field EC and the switchable polarization P_m were determined. The switching polarity in the saturation region turns out to be no more, in contrast to BaTiO3 and other materials, but less than the corresponding values obtained with short-term switching.
Keywords: piezoceramics, piezoelectric material, hot pressing, dielectric hysteresis
The expert system for practical use by doctors in hospitals is designed The systems is solve the problem of classification opinions on the gestosis development and degree during pregnancy risk. Multi-factor knowledge base derived based on the results of studies analyzed in the work, and includes a set of genomic and post-genomic signs of pregnancy complications. The main users of the system (doctors, researchers and patients) and their requirements for software implementation of the developed expert system. Structure of expert decision support system in the evaluation of the risk of preeclampsia, comprising components (characterizing developed information systems belonging to the class of expert systems), the functions and subjects were created. The types, feature space feature descriptions and attributes the knowledge base of these patients. The generalized algorithm of the system and the possibility of its further development were given.
Keywords: Expert system, knowledge base, requirements analysis, Statistical classification, feature space, gestosis, preventive diagnostics, a personified medicine
The problem of manufacturing technology heterostructures pezofaza - metal considered in the article. Complexity consists in the fact that during the removal of the polymer in the system at low temperatures are formed porous layers, formed powders separated metal layers, having island macrostructure. One way to solve the problem - reducing the firing temperature heterostructures. Proposed to decrease the sintering temperature by using of functionally active glass-phases. Reducing the sintering temperature of products also allows to replace platinum electrodes inexpensive silver-based alloys. Obtained by solid state reaction method of piezoceramic material has a low sintering temperature (980 ° C) and high electrical parameters. Found that not only the proportion of the vitreous mass, but also their qualitative influence on the properties of piezomaterials
Keywords: heterostructure glass phase, the sintering temperature, porosity, ferroelectric phase
Piezoelectric ceramics on the basis of the phase of (1-x) PbTiO3-xPbZrO3 is the basis of most high-performance piezoelectric materials. Electrophysical and mechanical properties of these materials can vary widely in different ways. Traditional methods include changes in composition within the morphotropic region and doping. Now is the study of the influence of topical makrolegirovaniya the material properties of the PZT system. As a model system was selected phase of the PZT system, the compositions of which MO belong, one of which contains a dopant in the sublattice (A) and another - in the sublattice dopants (B). The studies established that one of the effective ways of varying the parameters piezomaterials may be the formation of solid solutions on the basis of two or more piezoelectric phases having different combinations of electrical parameters
Keywords: Piezoelectric ceramics, doping, kombinorovanie, pezofaza, piezo
Laboratory technology was developed to fabricate flexible piezocomposites with ferroelectric phase - polymers having signal reception factorv • gv 5000 • 10-15 m2 / N. The values of the given coefficient were achieved by switching from a probabilistic (spontaneous) percolation to a correlated one in the process of forming material. This made the production of 0-1–3 piezocomposites, in which a part of piezophase has 0 connectivity, and the other part – 1 connectivity possible. To improve the efficiency of piezocomposite polarization before their manufacturing the surface of piezophase particles, which were obtained by the partial destruction of the porous frameworks, was treated with coupling agent, which did not only improve the polymer adhesion to piezophase, but also allowed the removal of water from the particle surface. The latter effect reduced the value of interfacial conductivity, i.e. prevented the voltage drop of the polarizing field. Matching of polymer conductivity and piezoceramic particles by determining the optimal polarization temperature was carried out as well.
Keywords: piezocomposites, percolation, connectivity, electrophysical properties
It was investigated the influence several additives and process parameters on the properties of piezoelectric ceramics based on PZT phase systems. It was shown that the use of the substitution of Pb2+ ions on the Bi3+, and Ti4+ ions, and Zr4+ to Fe3+ and Mn4+, as well as the method of "chemical assembly «allows to obtain increase the Curie temperature of ceramic samples of 50 - 170°C. The theoretical aspects of this area of research have been discussed in this article.
Keywords: ferroelectric phase, Curie temperature, ceramics, precursors, perovskite, a solid-state method, a method of «chemical assemblage