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In the present work, we have developed a new method for the fabrication of piezoactive ceramic matrix composites (CMC) ceramics/ceramics. Samples of piezoactive PZT/PZT composites with a mass concentration of components from 0% to 60% have been obtained. A study of microstructural features, as well as a gravimetric analysis of CMC, has been carried out. It has been shown that the developed method for CMC manufacturing provides the formation of microhomogeneous composite structures with a uniform distribution of ceramic filler particles in a microporous piezoceramic matrix without the formation of transition regions and additional crystalline phases. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive study of microstructure/properties interrelations for porous piezoceramics based on PZT composition was performed. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. Porosity dependencies of elastic, dielectric, piezoelectric and electromechanical coefficients of the porous ceramics in the relative porosity range 0-50% were obtained and analyzed. As a result of microstructure analysis, it was found that at any connectivity type (3–0, 3–3) and porosity up to 50% the real structures of porous piezoceramics were close to the matrix medium structure with continuous piezoceramic skeleton. It was also revealed that the microstructural features of porous piezoceramics define the character of the dependences of the dielectric, piezoelectric and electromechanical properties of porous piezoelectric ceramics on porosity. In conclusion, microstructure/properties interrelations, as well as new applications of porous piezoceramics were discussed. [ABSTRACT FROM AUTHOR]

In this paper, the results of experimental study of dispersion characteristics of complex electromechanical parameters of ferroelectrically "hard" porous piezoceramics based on PZT composition were presented. Experimental samples of porous piezoceramics were fabricated using a modified method of burning-out a pore former. The complex constants of porous piezoceramics with relative porosity 16% and their frequency dependences were measured using the piezoelectric resonance analysis method. As a result of experimental studies, regions of elastic, piezoelectric and electromechanical dispersion, characterized by anomalies in the frequency dependences of the imaginary and real parts of the complex constants of porous piezoelectric ceramics were found. It was revealed also that the microstructural features of porous piezoceramics determine the character of frequency dependences of complex electromechanical parameters of porous piezoelectric ceramics. In conclusion, the microstructural and physical mechanisms of electromechanical losses and dispersion in porous piezoceramics were discussed. [ABSTRACT FROM AUTHOR]

This article presents the results of experimental study of the frequency dependences of complex electromechanical characteristics of layered ferroelectrics based on bismuth-containing compounds with a perovskite-like structure. Textured ceramics of the composition 0.9Na0.5Bi4.5Ti4O15-0.1PbNb0.5Cr0.5O3 were prepared by uniaxial hot pressing method with a special sintering conditions. Experimental disk-shaped samples were cut from the hot-pressed blocks and polarized parallel (E ǁ P) and perpendicular (E ⊥ Р) to the pressing axis (P). Complex electromechanical parameters of textured piezoceramics and their frequency dependences in the frequency range up to 50 MHz were measured and analyzed using PRAP iterative automatic method. [ABSTRACT FROM AUTHOR]

An experimental study of the microstructural features and complex electromechanical parameters of lead-free ferroelectric ceramics based on solid solutions of the sodium-lithium niobate system was carried out. The phase distribution, as well as grain and domain structure were studied by piezoresponse force microscopy and scanning electron microscopy. A complete set of complex elastic, dielectric, and piezoelectric parameters of lead-free ferroelectric ceramics Na0.87Li0.13Sr0.01Nb0.99O3 + 1 at.% SiO2 was measured and analyzed using the Piezoelectric Resonance Analysis Program automatic iterative method. The frequency dependences of complex electromechanical parameters of the samples were measured in the frequency range up to 90 MHz. [ABSTRACT FROM AUTHOR]

In this article, a correlation between microstructure and properties for porous piezoceramics of the composition Pb0.95Sr0.05Ti0.47Zr0.53O3 + 1% Nb2O5 was studied in detail. Experimental samples of porous piezoceramics were obtained using a modified method of burning-out a pore former. Porosity dependences of dielectric, elastic, piezoelectric, and electromechanical coefficients of the porous ceramics in the relative porosity range 0–50% were measured and analyzed. It was revealed that the microstructural features of porous piezoceramics defined the character of the porosity dependences of the dielectric, piezoelectric, and electromechanical properties of porous piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

An experimental study of the origin of elastic, dielectric, and piezoelectric losses in ceramic-matrix piezocomposites PZT/α-Al2O3 with different volume concentrations and particle sizes of α-Al2O3 microcrystalline filler was performed. The microstructural features and concentration dependences of the imaginary and real parts of the complex elastic, dielectric, and piezoelectric characteristics of composite piezoelectric elements were studied. The analysis of the obtained dependences was carried out and a physical interpretation of the obtained results was proposed. [ABSTRACT FROM AUTHOR]

The electromechanical properties and microstructural features of ceramic-matrix piezocomposites PZT/α-Al2O3 with different volume fractions of microcrystalline α-Al2O3 filler were studied. The concentration dependences of the complex elastic and electromechanical parameters of piezoelectric elements on α-Al2O3 microcrystals concentration were measured. It was found that, along with the influence of the non-piezoelectric phase α-Al2O3, the microporosity of the piezoceramic matrix appearing during sintering plays a decisive role in the formation of the electro-physical properties of ceramic-matrix piezocomposites PZT/α-Al2O3. [ABSTRACT FROM AUTHOR]

An experimental study of the origin of elastic, dielectric, and piezoelectric losses in ceramic-matrix piezocomposites PZT/α-Al2O3 with different volume concentrations and particle sizes of α-Al2O3 microcrystalline filler was performed. The microstructural features and concentration dependences of the imaginary and real parts of the complex elastic, dielectric, and piezoelectric characteristics of composite piezoelectric elements were studied. The analysis of the obtained dependences was carried out and a physical interpretation of the obtained results was proposed. [ABSTRACT FROM AUTHOR]

The electromechanical properties and microstructural features of ceramic-matrix piezocomposites PZT/α-Al2O3 with different volume fractions of microcrystalline α-Al2O3 filler were studied. The concentration dependences of the complex elastic and electromechanical parameters of piezoelectric elements on α-Al2O3 microcrystals concentration were measured. It was found that, along with the influence of the non-piezoelectric phase α-Al2O3, the microporosity of the piezoceramic matrix appearing during sintering plays a decisive role in the formation of the electro-physical properties of ceramic-matrix piezocomposites PZT/α-Al2O3. [ABSTRACT FROM AUTHOR]

In this work, we studied elastic and electromechanical characteristics and microstructural features of piezoactive ceramic-matrix composites PZT/LiNbO3 with a volume fraction of microcrystalline LiNbO3 filler from 0 to 15 vol. %. The dependences of the complex elastic and electromechanical parameters of composite piezoelectric elements on LiNbO3 microcrystals concentration were measured. It was found that in the formation of the electrophysical properties of ceramic-matrix composites PZT/LiNbO3, the microporosity of the piezoceramic matrix appearing during the composite sintering played a decisive role. [ABSTRACT FROM AUTHOR]

Samples of a single-layer composite of a piezoceramic-polymer system were investigated. The basic electromechanical parameters of the experimental samples were measured. Anisotropy of the electromechanical coupling coefficients and mechanical Q factors for thickness and radial modes of oscillations, as well as the corresponding piezoelectric moduli, was revealed. [ABSTRACT FROM AUTHOR]

In this work, complex studies of the elastic dispersion and losses in porous piezoceramics based on solid solutions of the PZT system were carried out. Full set of complex constants of porous ceramics with different porosity and their frequency dependences were measured using the piezoelectric resonance analysis method.The microstructural and physical mechanisms of elastic losses and dispersion in porous piezoceramics were considered. [ABSTRACT FROM AUTHOR]

In this work, the frequency dependences of complex piezoelectric, dielectric, and elastic parameters of lead-free ferroelectric ceramics based on solid solutions of the (Na, Li)NbO3 system were studied in the frequency range up to 100 MHz. A complete set of complex parameters of lead-free ferroelectric ceramics was measured using the PRAP automatic iterative method. It was shown that the studied lead-free ferroelectric ceramics are characterized by low attenuation of ultrasonic waves and lack of dispersion in a wide frequency range, and can be used in high-frequency ultrasonic transducers for medical and nondestructive testing equipment. [ABSTRACT FROM AUTHOR]

The article presents a new method of electromechanical characterization of ferroelectric materials. The measurements of the complex elastic, electromechanical, and piezoelectric parameters of ferroelectric ceramics were fulfilled using the piezoelectric resonance analysis method. To study nonlinear processes occurring in ferroelectric ceramics under the external influences the dc electric field, dependencies of the complex electromechanical parameters of the PZT type piezoceramics were measured and analyzed. [ABSTRACT FROM AUTHOR]

Method of digital piezomaterials fabrication based on mixed composites of the "piezoelectric ceramics-polymer" system is presented. The materials intend for use as precursors in the manufacture of piezoelectric elements using the technology of layer-by-layer bonding of powders. The method of investigation of these materials and frequency dependences of their electromechanical properties is described. [ABSTRACT FROM AUTHOR]

Recent advances in the field of physical acoustics, imaging, and images processing, piezoelectric materials and ultrasonic transducer designs have led to the emergence of new methods and equipment for ultrasound diagnostics, therapy and esthetic medicine, as well as the development of traditional and emerging new application fields. One of the promising applications of piezoceramics and composite materials are ultrasonic transducers, in particular, high intensity focused ultrasound (HIFU) transducers for medical therapeutic devices. This paper describes the results of the development of mathematical models, numerical modeling and optimization of acoustic fields and designs of composite HIFU transducers, which were made from porous piezoceramics. [ABSTRACT FROM AUTHOR]

The paper describes the results of the experimental study of the properties of piezoceramics, ceramic matrix composites "ceramics/crystal," and porous ceramics based on lead-free sodium-lithium niobates (Na, Li)NbO3 and sodium-potassium niobates (Na, K)NbO3 compositions. The measurements of elastic, dielectric and piezoelectric parameters, as well as microstructural studies of experimental samples of lead-free porous piezoelectric ceramics and composites were performed. It was shown that the use of alkali metal niobates in the form of ceramic matrix composites and porous ceramics allows to increase the main functional parameters of these materials and makes them competitive with piezoceramics of the PZT system. The developed lead-free porous and composite materials have a unique combination of parameters and can be used for the manufacture of ultrasonic transducers and devices for a wide range of applications, including medical and nondestructive testing equipment. [ABSTRACT FROM AUTHOR]

Matrix piezocomposites of the triple "piezoceramic-polymer-metal" system with quasi-one-dimensional conductive metal particles with a general connectivity type of 0-3-1 (where 0, 3, 1 - dimensions of the composites components) were fabricated. Their electromechanical properties were studied. A nonlinear dependence of the conductivity of a polymer-metal matrix of the composite on the ratio of the geometric dimensions of composite elements and sizes of its constituent components was found. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive study including computer 3D simulation, microstructural studies, and experimental measurements of different composites structures was carried out. The Wave 3000 finite differences software package was used for simulation. The results of simulation of longitudinal ultrasonic waves propagation in ceramics/crystal and ceramics/metal ceramic matrix composites are presented. Finite difference modeling made it possible to reveal the characteristic features of the propagation of longitudinal waves in inhomogeneous piezoelectrically active ceramic matrix composites. The simulation results were compared with the experimental data obtained by impedance spectroscopy and ultrasonic methods. Anomalies of complex elastic moduli near corresponding percolation thresholds and elastic dispersion regions were found out. [ABSTRACT FROM AUTHOR]

The paper describes the results of the development and study of therapeutic transducers intended for the implementation of new methods of complex combinational treatment of biological tissues. The methods are based on synergetic combination of different physical factors such as dynamical focusing and multifrequency influences, ultrasonic shear and standing waves impact, ultrasonic heating and cavitation, radio-frequency heating (RF), vacuum massage, as well as ultrasonically assisted drags delivery and activation. The original designs of sectored HIFU transducers made from porous piezoelectric ceramics were developed and studied. The technology of manufacturing of spherical focusing elements from porous piezoceramics was described. The universal therapeutic module for combinational treatment of superficial tissues comprising electronic block, vacuum system, and therapeutic head consisting of USW and RF transducers was designed and tested. The efficacy, safety and selectivity of developed therapeutic transducers for various therapeutic, surgical and cosmetic applications were proved by the results of ex vivo experiments with different biological tissues. [ABSTRACT FROM AUTHOR]

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Through the developed technique, the finite-element optimization and the experimental validation of the construction and parameters of low-frequency bimorph piezoelectric transducers designed for the diagnostics and activation of oil wells are carried out. [ABSTRACT FROM AUTHOR]

Numerous techniques using complex material constants have been proposed to take into account losses in low-Qpiezoelectrics and to overcome limitations in the IEEE Standard. Iterative methods provide a means to accurately determine the complex coefficients in poled piezoceramics from complex impedance resonance measurements. In this paper the piezoelectric resonance analysis iterative method and program (PRAP) have been used for a set of standard geometries and resonance modes needed to complete complex characterization of lossy piezoceramics. The complex sets of elastic, dielectric and piezoelectric coefficients as well as the 6mm reduced matrix for PZT-type porous piezoceramics were presented. [ABSTRACT FROM PUBLISHER]

In this paper an experimental study of different ceramic matrix composites with high elastic losses (porous piezoceramics, composites ceramics/crystals) were carried out. Complex sets of elastic, dielectric, and piezoelectric parameters of the porous piezoceramics and ceramic matrix piezocomposites were determined by the impedance spectroscopy method using Piezoelectric Resonance Analysis software. Microstructure of polished and chipped surfaces of composite samples was observed with the optical and scanning electron microcopies. Experimental frequency dependencies of attenuation coefficients and ultrasonic velocities for different ceramic matrix composites were compared with the theoretical results obtained using general Kramers-Kronig relations between the ultrasonic attenuation and dispersion. [ABSTRACT FROM PUBLISHER]

In this paper an experimental study of different piezoelectric materials for energy harvesting applications, as well as experimental results for various types of piezoelectric materials and piezoelements were presented. Various types of hot-pressed and conventionally sintered PZT piezoceramics, porous PZT piezoceramics, and multilayer PZT/PZT ceramic piezocomposites with diverse ferroelectric “hardness” were fabricated, optimized and tested. Experimental results comprising cyclic loading at different load resistances and mechanical stresses for different types of piezoelements were presented. It was shown that porous ceramics (relative porosity 20%, d33= 410 pC/N, ϵT33/ϵ0= 1100) provide 1.5–2 times higher power efficiency at cyclic loadings than the dense hot-pressed ceramics and can be used as piezogenerators at low loading pressures (up to 5 MPa). The possible applications of developed materials in energy harvesting devices as well as the empirical criteria of piezoelectric materials efficiency were discussed. [ABSTRACT FROM PUBLISHER]