This paper studies the dielectric spectra of solid solutions (SS) of the system (1 − x − y)NaNbO3–xKNbO3 –yCdNb2O6y= 0.075, x= 0.05 ÷ 0.30 in the temperature range (10 ÷ 900) K. The formation of a local maximum was established in the interval (260 ÷ 300) K at small x values, which, as KNbO3 increases, is gradually blurred and becomes an inflection point. Detected in SS with x = 0.05 ÷ 0.10, the shift of the maxima of dependences 𝜀′/ 𝜀0(T) and 𝜀′′/𝜀0 (T), depending on the frequency of the electric field at the temperature ranges (300 ÷ 304) K and (258 ÷ 271) K, is not related to relaxation. This anomaly may indicate a crystallographic disorder to A and B positions. The conclusion is made about the expediency of using the obtained results for the development of functional ferroactive materials.This paper studies the dielectric spectra of solid solutions (SS) of the system (1 − x − y)NaNbO3–xKNbO3 –yCdNb2O6y= 0.075, x= 0.05 ÷ 0.30 in the temperature range (10 ÷ 900) K. The formation of a local maximum was established in the interval (260 ÷ 300) K at small x values, which, as KNbO3 increases, is gradually blurred and becomes an inflection point. Detected in SS with x = 0.05 ÷ 0.10, the shift of the maxima of dependences 𝜀′/ 𝜀0(T) and 𝜀′′/𝜀0 (T), depending on the frequency of the electric field at the temperature ranges (300 ÷ 304) K and (258 ÷ 271) K, is not related to relaxation. This anomaly may indicate a crystallographic disorder to A and B positions. The conclusion is made about the expediency of using the obtained results for the development of functional ferroactive materials.

Crystallographic texturing enables the design of piezoelectric polycrystals that outperform traditional random polycrystals by exhibiting outstanding piezoelectric properties. In this work, phase-field modeling and computer simulation were employed to study the effect of crystallographic texture on the piezoelectric properties of ferroelectric polycrystals at the domain level. Domain evolutions for single crystal, random polycrystal, and textured polycrystal are systematically simulated. The simulations reveal that the [001]-textured polycrystal can fully exploit the intrinsic anisotropic properties of piezoelectric materials by exhibiting a piezoelectric coefficient that is as large as that of single crystal while being much larger than that of random polycrystal. To better understand the mechanism of piezoelectricity enhancement by crystallographic texturing, a theoretical analysis based on Landau theory is provided. In comparison with random polycrystal, the textured polycrystal manifests a flatter energy landscape and thus possesses a higher piezoelectric coefficient.Crystallographic texturing enables the design of piezoelectric polycrystals that outperform traditional random polycrystals by exhibiting outstanding piezoelectric properties. In this work, phase-field modeling and computer simulation were employed to study the effect of crystallographic texture on the piezoelectric properties of ferroelectric polycrystals at the domain level. Domain evolutions for single crystal, random polycrystal, and textured polycrystal are systematically simulated. The simulations reveal that the [001]-textured polycrystal can fully exploit the intrinsic anisotropic properties of piezoelectric materials by exhibiting a piezoelectric coefficient that is as large as that of single crystal while being much larger than that of random polycrystal. To better understand the mechanism of piezoelectricity enhancement by crystallographic texturing, a theoretical analysis based on Landau theory is provided. In comparison with random polycrystal, the textured polycrystal manifests a flatter energy landscape and thus possesses a higher piezoelectric coefficient.

In this paper, 0.36Pb(Ni1/3Nb2/3)O3–0.24PbZrO3–0.40PbTiO3(PNN-PZT) ceramic was prepared, and texture engineering was performed on this PNN-PZT ceramic to improve its electromechanical properties and temperature stability. Single element ultrasonic transducers were prepared using PNN-PZT, PNN-PZT textured ceramics, and their performance were evaluated and compared using a PZT-5H ceramic based transducer as the benchmark. It is shown that the sensitivity and bandwidth of the PNN-PZT textured ceramic-based transducer are much superior to regular PNN-PZT ceramic and PZT-5H ceramic based transducers.In this paper, 0.36Pb(Ni1/3Nb2/3)O3–0.24PbZrO3–0.40PbTiO3(PNN-PZT) ceramic was prepared, and texture engineering was performed on this PNN-PZT ceramic to improve its electromechanical properties and temperature stability. Single element ultrasonic transducers were prepared using PNN-PZT, PNN-PZT textured ceramics, and their performance were evaluated and compared using a PZT-5H ceramic based transducer as the benchmark. It is shown that the sensitivity and bandwidth of the PNN-PZT textured ceramic-based transducer are much superior to regular PNN-PZT ceramic and PZT-5H ceramic based transducers.

Solid solutions (SS) of 3- and 4-component systems based on lead titanate-zirconate were prepared by the method of solid-phase reactions and uniaxial hot pressing. The dependences of the relative permittivity of polarized samples on the electronegativity (EN) of their constituent cations have been studied. The ferro-hardness of the SS (the stability of the domain structure to external influences) is shown to be directly dependent on the EN of elements B in the corresponding oxidation states, i.e., the degree of covalence of the B–O bond. The deviation from this dependence in SS with Ni and Cd is explained by their individual features, which result in changes in the degree of bond covalence in both cationic sublattices. The conducted crystal-chemical analysis made it possible to choose promising SS when creating ferroelectric materials, including textured piezoelectric ceramic materials for piezoelectric transducers for various purposes: Piezotransformers, piezoelectric motors, ultrasonic emitters, filter devices, ultrasonic flaw detectors, accelerometers, etc.Solid solutions (SS) of 3- and 4-component systems based on lead titanate-zirconate were prepared by the method of solid-phase reactions and uniaxial hot pressing. The dependences of the relative permittivity of polarized samples on the electronegativity (EN) of their constituent cations have been studied. The ferro-hardness of the SS (the stability of the domain structure to external influences) is shown to be directly dependent on the EN of elements B in the corresponding oxidation states, i.e., the degree of covalence of the B–O bond. The deviation from this dependence in SS with Ni and Cd is explained by their individual features, which result in changes in the degree of bond covalence in both cationic sublattices. The conducted crystal-chemical analysis made it possible to choose promising SS when creating ferroelectric materials, including textured piezoelectric ceramic materials for piezoelectric transducers for various purposes: Piezotransformers, piezoelectric motors, ultrasonic emitters, filter devices, ultrasonic flaw detectors, accelerometers, etc.

This paper is devoted to a comprehensive study on a new type of microwave structures named magnetoelectric (ME) gradient structures. These structures are studied in this paper to understand the possibilities and application principles in feasible devices. The structure under study was calculated at different values of the applied electric field and different values of the relative permittivity of the artificial dielectric layer. The layered multiferroic structure in inhomogeneous electric and magnetic fields was calculated on the basis of the previously proposed mathematical model. The eigenwaves spectrum for several considered cases was the result of the performed calculation. The concept of using ME gradient structures in the design of electronically controlled microwave devices is formed on the basis of the results of a numerical experiment. Structures of this type will preferably be used in electronically controlled devices for the directional transmission of microwave signals, as it was shown in the theoretical part of the paper.This paper is devoted to a comprehensive study on a new type of microwave structures named magnetoelectric (ME) gradient structures. These structures are studied in this paper to understand the possibilities and application principles in feasible devices. The structure under study was calculated at different values of the applied electric field and different values of the relative permittivity of the artificial dielectric layer. The layered multiferroic structure in inhomogeneous electric and magnetic fields was calculated on the basis of the previously proposed mathematical model. The eigenwaves spectrum for several considered cases was the result of the performed calculation. The concept of using ME gradient structures in the design of electronically controlled microwave devices is formed on the basis of the results of a numerical experiment. Structures of this type will preferably be used in electronically controlled devices for the directional transmission of microwave signals, as it was shown in the theoretical part of the paper.

Domain pattern is the carrier of electromechanical property. A novel domain pattern will open a gate for ferroelectric nanodevice. A distinctive topological domain pattern termed as hierarchical vortex (Hvo) has been found in polycrystalline ferroelectric based on the first-principles-based atomistic method. The Hvo pattern displays a unique structure, which is a flux-closing vortex encircle an anti-vortex or a vortex and anti-vortex pair (VA). Each Hvo structure could be regarded as a single vortex to forming a vortex–anti-vortex pair with anti-vortex or forming a vortex–vortex array with the vortex. The mechanism of HVo obtained in polycrystalline ferroelectric has been found that the grain boundary (GB) equals the domain wall when the first-order vortex is in the vortex. The HVo will open a new view of the domain topology pattern and its evolution.Domain pattern is the carrier of electromechanical property. A novel domain pattern will open a gate for ferroelectric nanodevice. A distinctive topological domain pattern termed as hierarchical vortex (Hvo) has been found in polycrystalline ferroelectric based on the first-principles-based atomistic method. The Hvo pattern displays a unique structure, which is a flux-closing vortex encircle an anti-vortex or a vortex and anti-vortex pair (VA). Each Hvo structure could be regarded as a single vortex to forming a vortex–anti-vortex pair with anti-vortex or forming a vortex–vortex array with the vortex. The mechanism of HVo obtained in polycrystalline ferroelectric has been found that the grain boundary (GB) equals the domain wall when the first-order vortex is in the vortex. The HVo will open a new view of the domain topology pattern and its evolution.

This paper presents a theoretical model for describing the thermodynamic properties of doped ferroelectric crystals based on a modified Weiss mean-field approach. Accounting for quadrupole and octupole terms in the expression for the effective field within the Weiss model makes it possible to move from the Langevin equation to the Landau–Ginzburg equation. Furthermore, the coefficients of the Landau–Ginzburg equation can be expressed in terms of the physical parameters of the crystal lattice. For these parameters, analytical expressions are proposed that describe their change when adding dopants in ceramic matrix composites. Perovskite barium titanate ceramics with a variety of inclusions is considered as an application example of the developed method. The obtained agreement between the analytical and experimental results for barium titanate ceramics with lanthanum/magnesium/zirconium dopants gives us hope of the applicability of the present theory to the calculation of other doped ferroelectrics as well.This paper presents a theoretical model for describing the thermodynamic properties of doped ferroelectric crystals based on a modified Weiss mean-field approach. Accounting for quadrupole and octupole terms in the expression for the effective field within the Weiss model makes it possible to move from the Langevin equation to the Landau–Ginzburg equation. Furthermore, the coefficients of the Landau–Ginzburg equation can be expressed in terms of the physical parameters of the crystal lattice. For these parameters, analytical expressions are proposed that describe their change when adding dopants in ceramic matrix composites. Perovskite barium titanate ceramics with a variety of inclusions is considered as an application example of the developed method. The obtained agreement between the analytical and experimental results for barium titanate ceramics with lanthanum/magnesium/zirconium dopants gives us hope of the applicability of the present theory to the calculation of other doped ferroelectrics as well.

Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm (PG6) with embedded KNO3 have been studied at the temperature diapason of 300–430 K and at frequencies of 0.1–3 × 106 Hz on cooling. X-ray diffraction studies of these samples have shown, that in modified and unmodified composites there is a mixture of the low-temperature paraelectric phase (α-phase) and the ferroelectric γ-phase. In modified composites, a decrease in permittivity and conductivity is observed. Dielectric response has been analyzed in the framework of modern theoretical models. Two relaxation processes have been identified and their origin has been determined. It has been found that the main contribution to the dielectric response of nanocomposite material PG6+KNO3 is provided by charge polarization on interfaces, which can be governed by modifying the inner pore surfaces. DC-conductivity of both composites has been estimated and the activation energies have been determined. Activation energy change observed in a vicinity of 360 K is attributed to the phase transformation and the appearance of KNO3α-phase.Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm (PG6) with embedded KNO3 have been studied at the temperature diapason of 300–430 K and at frequencies of 0.1–3 × 106 Hz on cooling. X-ray diffraction studies of these samples have shown, that in modified and unmodified composites there is a mixture of the low-temperature paraelectric phase (α-phase) and the ferroelectric γ-phase. In modified composites, a decrease in permittivity and conductivity is observed. Dielectric response has been analyzed in the framework of modern theoretical models. Two relaxation processes have been identified and their origin has been determined. It has been found that the main contribution to the dielectric response of nanocomposite material PG6+KNO3 is provided by charge polarization on interfaces, which can be governed by modifying the inner pore surfaces. DC-conductivity of both composites has been estimated and the activation energies have been determined. Activation energy change observed in a vicinity of 360 K is attributed to the phase transformation and the appearance of KNO3α-phase.