A model of a novel 1–3-type composite containing two ferroelectric components is put forward. In this composite, ferroelectric single crystal (SC) rods and ferroelectric ceramic rods are distributed in a polymer matrix. For a lead-free 1–1–3 composite based on domain-engineered [Lix(K1−yNay)1−x](Nb1−zTaz)O3:Mn SC, effective piezoelectric coefficients d3j∗ and g3j∗ and energy-harvesting figures of merit (FOMs) d3j∗g3j∗ are studied taking an active influence of the ferroelectric components into account. In a new m–mc diagram, regions of volume fractions of SC (m) and ceramic (mc) are determined where FOM d33∗g33∗ changes from 6⋅10−11 to 9⋅10−11 Pa−1. Effective parameters of the 1–1–3 and related 1–0–3 composites are compared, and consistency is shown. The large longitudinal piezoelectric coefficient g33∗ and FOM d33∗g33∗ of the lead-free 1–1–3 composite are to be of interest in piezoelectric sensorics and energy harvesting.

This paper discusses ways to search for lead-free functional materials for various applications. Using the example of the solid solution systems based on alkali metal niobates, the influence of the position on the phase diagram of the corresponding systems, the number of the components in them, and modification with mono- and combined metal oxides on their characteristics is shown. It has been established that the most effective in terms of piezoelectric characteristics are the solid solution systems in or near the morphotropic region, with 3 or 4 components. A number of materials have been developed to create highly sensitive electromechanical transducers, ultrasonic delay lines and other applications.

A mathematical model of dynamic processes in a composite plate of prestressed piezoelectric (PE) and piezomagnetic (PM) layers is proposed. It is assumed that the initial strain state in the components of the plate is uniform and is induced by the action of initial mechanical stresses. In the quasi-static approximation, problems of shear horizontally polarized surface acoustic waves (SH-SAW) propagation in a PE/PM plate made of prestressed materials are considered. It is assumed that the materials of the plate layers in their natural state (NS) have symmetry class 6mm. The adhesion conditions are satisfied at the interface between the layers. The external surfaces of the heterostructure are in contact with the vacuum and are free from mechanical stress. Depending on the nature of the electrical and magnetic conditions specified on the external surfaces, four types of problems are considered. Using the example of a problem with electrically closed and magnetically open conditions on the external surfaces of a PZT-5H/CoFe2O4 plate, the features of the influence of the nature and magnitude of the initial mechanical effects on the velocities of SH waves are investigated. The possibility of changing the velocity characteristics of SAWs due to the initial mechanical effects is shown. The results are presented in dimensionless parameters and may be of significant interest for optimizing the structure of new materials in the development and design of devices and equipment operating on SH-SAW.

In this paper, we present the experimental results of the comprehensive study of the microstructural features and complex dielectric, elastic and electromechanical properties of the ferroelectrically “hard” piezoceramics based on the lead zirconate titanate (PZT) composition. For the measurements and analysis of the real and imaginary parts of the complex parameters of the studied piezoceramics as well as their frequency dependences, we used precision impedance analyzer Agilent 4294A and Piezoelectric Resonance Analysis Program (PRAP) software. We have found that the studied piezoceramics demonstrate a unique combination of dielectric, elastic and electromechanical parameters along with very low elastic and electromechanical losses and dispersion over a wide frequency range and can be used in various high-power ultrasonic applications.

This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PZT system. Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001–5Hz were performed by means of the electromechanical response characterization system (STEPHV) and program (STEP). It was found that the coercive field, remnant and saturation electric displacement, area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency. As a result of this study, complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.

The paper presents the results of experimental studies of synaptic plasticity in a memristive memory element based on nanocrystalline ZnO films grown by pulsed laser deposition. The obtained results can be used in the development of technological bases for the formation of high-performance multi-level artificial synapses for elements of neuroelectronics and hardware neural networks.

This paper demonstrates the influence of deposition parameters (temperature, power and time) and stoichiometric composition of thin aluminum nitride (AlN) coatings, the thickness of which varied from 320 to 1100nm deposited by DC reactive magnetron sputtering on their microstructure, mechanical and microtribological properties. The investigation revealed that high-deposition power (150W) and temperature (200∘C) lead to sputtering of coatings with high roughness, low mechanical and high microtribological properties. Such a phenomenon occurred due to the formation of a coarse-grained structure, high porosity and dendritic growth of the coating, which was observed on their cross-sections. Reducing the deposition temperature to 20∘C and power to 80–100W allowed to obtain a fine-crystalline structure demonstrating low-roughness values with crystallites evenly and compactly distributed over the surface. Such coatings showed higher mechanical and low microtribological properties. Surface resistivity was lower on coatings with a fine crystalline structure and correlated with the nitrogen content of the coating. In the course of the research, it was demonstrated that the optimal combination of microstructure, mechanical, microtribological properties and electrical resistivity for practical use in micro- and nanosensory applications may be achieved for the AlN coating with the thickness of 320nm and 29.71at.% N, deposited at 20∘C, 100W and 20min. Such a coating possesses the highest values of mechanical properties, low roughness and specific surface resistance, as well as low coefficient of friction and specific volumetric wear compared to all coatings under study.

Pure and superstoichiometric modified by 2wt.% Bi2O3 and 2wt.% manganese oxide (Mn2O3) ceramic samples of the binary system 0.71BiFeO3-0.29BaTiO3 were fabricated using conventional ceramic technology by double solid-phase synthesis with following sintering. Mechanical activation of synthesized powders was carried out at the stage of manufacturing press powders prepared for sintering. X-ray analysis at room temperature showed that all studied ceramics have pseudo-cubic symmetry. Grain morphology, dielectric and piezoelectric properties of selected solid solutions were investigated. The modification increased the homogeneity of the material, dielectric constant and piezomodulus d33 and also resulted in a decrease in the dielectric loss tangent. The highest piezoelectric coefficient d33=105 pC/N was obtained. Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior and region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 740–770K.

Constructed existence areas of different oxygen–octahedral structures of complex oxides are considered and compared. They are found on numerous facts of certain complex oxide compositions of three different structure types: successful and not-so-successful syntheses, on the one hand, and their interatomic bond characteristics calculation and analysis — on the other hand. Developed procedures of the crystal structure detailing the theoretical definition for every oxygen–octahedral structure and its constructing existence areas are shown. By using every structure existence area, one may predict the possibility of the specified complex oxides crystallization in the corresponding structure type.

The known multiferroics (MFs)-ternary oxides with perovskite-type structure PbB0,5′B0,5′′O3 that undergo successive phase transitions (PTs), ferroelectric (FE) or antiferroelectric (AFE) — at the Curie temperature, TC, and ferromagnetic (FM), antiferromagnetic (AFM) or ferrimagnetic at the Néel temperature, TN —and classical FEs and AFEs are considered. The dependences of the TC, TN on the interatomic bond A–O strains in their perovskite structures have been constructed. On constructed dependencies, some ternary MFs are discovered, which have comparatively high temperatures of first FE or AFE and second magnetic PTs but their difference TC–TN values are high comparatively with the binary MFs.

Ceramic samples of (1−x)BiFeO3−xPbFe0.5Sb0.5O3(BFO–xPFS), (1−x)BiFeO3−xSrFe0.5Sb0.5O3(BFO–xSFS) where (x=0.05,0.1,…,0.9), (1−x)BiFeO3−xBaFe0.5Nb0.5O3 (BFO–xBFN) and (1−x)BiFeO3−xSrFe0.5Nb0.5O3 (BFO–xSFN) where (x=0,0.01,0.02,…,0.1,0.2,…,1) solid solutions with a perovskite structure were obtained. Mössbauer studies have shown that the Neel temperature TN concentration dependences of the systems studied are in good agreement with TN(x) calculated under the assumption of the ordered distribution of Fe3+ and nonmagnetic Sb5+ ions in the lattice. The TN values obtained for BFO–xBFN and BFO–xPFS are close to the values, calculated for cases of the disordered and ordered distribution of Fe3+ and nonmagnetic Nb5+ and Sb5+ ions in the lattice, respectively. The TN values of BFO–xSFN and BFO–xSFS are in the range between the calculated values for ordered and disordered cases. Moreover the anomaly on the TN(x) dependence for the BFO–xBFN and BFO–xSFN systems was found near x=0.7. This anomaly is most likely related to the destruction of the magnetic super exchange via the empty 6p state of Bi3+ ions.