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In this paper, we present the electric field controllable diffractive optical elements in strontium–barium niobate single crystals with stable tailored spiral-shaped domain structure and demonstrate the generation of optical beam with orbital angular momentum. The required domain pattern was created in the sample with initial domain structure by electric field application using the photolithographically defined liquid electrode. A series of bipolar triangular electric field pulses were applied to the sample for determination of the optimal parameters for complete polarization switching under the electrode. The stable tailored domain pattern of the spiral shape was created by the application of the unipolar pulse of a special shape. The complete switching under the electrode and partial switching under the photoresist layer have been revealed. The imaging by Cherenkov-type second harmonic generation microscopy confirmed that the created domain structure reaches the opposite polar surface. The imaging of the diffraction pattern of the laser beam passing through a voltage-biased DOE confirmed the formation of the beam with orbital angular momentum. The half-wave voltages of 237V and 302V for wavelength 632.8nm and 532nm, respectively, for 2-mm-thick sample were measured. The obtained knowledge can be used for the development of domain engineering methods in strontium–barium niobate single crystals for the creation of tailored domain structures for manufacturing of electric field controllable diffractive optical elements.

The phenomenon of domain magnetic shielding by the magnetic sample of external and intrinsic magnetostatic field has been revealed. In this work, we investigate the possibility for detection of the shape and size of magnetic impurity based on the shape of magnetic domain configuration in magnetic film. We show that due to the influence of magnetostatic field of stripe domain structure in magnetic film on the magnetostatic field of magnetic impurity, one can determine the shape and size of this impurity.

Influence of anisotropy on a bending of a magnetic stripe domain wall due to a magnetostatic stray field of a cylindrical magnetic domain (CMD) that is located within the stripe one is under investigation. It is revealed that for a specific set of physical parameters of the domain structure, energy of domain wall bending anisotropy can suppress the bending. An analytical expression for the bending shape is obtained on account of a change of both magnetostatic energy of the configuration and energy of anisotropy of the domain wall.

Magnetic ordering in a mixed domain structure composed of a stripe domain and asymmetrically localized magnetic impurity inside the stripe domain was investigated. The analytical expression for domain walls deformation mediated by the influence of the magnetostatic stray field of the asymmetrically localized magnetic impurity was obtained. The calculations were done for the magnetic film with parameters which are typical for films used in magnetic memory. Experimental implementation of the mixed domain structure composed of the stripe domain and asymmetrically localized magnetic impurity inside the stripe domain was done in (BiLu)₃(FeGa)₅O₁₂ film. Obtained analytical solution for the shape of stripe domain walls distortion is in excellent agreement with the experimental results.

In this letter, conclusive experimental evidence is presented for the coexistence of two phases within individual grains in the system (Bi_0.5Na_0.5TiO₃)_0.91-(BaTiO₃)_0.06-(K_0.5Na_0.5NbO₃)_0.03. Electron diffraction data unequivocally reveal the presence of a rhombohedral and a tetragonal phase with space group R3c and P4bm, respectively, both on the nanoscale level. Superlattice reflections, observed in the corresponding selected area electron diffraction, were used to identify the rhombohedral and tetragonal phase present at different regions within one grain. It is thought that the rhombohedral phase acts as a nucleation site for the phase transformation monitored under applied electrical field. The coexistence of these two phases in conjunction with the triggered tetragonal to rhombohedral phase transformation rationalizes the high bipolar and unipolar strain recorded for this lead-free ferroelectric material.

(Ba_0.3Bi_0.7)(Mg_0.05Fe_0.6Ti_0.35)O₃ ceramics were either doped with vanadium or sintered in calcined powder with the same composition. Compared to an undoped ceramic sintered without the calcined powder, both ceramics showed reduced leakage current densities (lower than 1 × 10^-7 A/cm²) and absence of dielectric relaxation behaviors observed in frequency- and temperature-dependent dielectric measurements. The Curie temperatures of both samples were higher than 460°C. The maximum field-induced strain over the applied field, S_max/E_max, of 366 pm/V of the undoped ceramic sintered without the calcined powder increased to 455 and 799 pm/V for the V-doped ceramics and the ceramics sintered with the calcined powder, respectively. The increase was related to a reduced concentration of bismuth vacancy–oxygen vacancy defect dipoles.

The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate. The presence of a “special” critical temperature $T_d$ on the temperature dependences of the permittivity $𝜀(T)$ and the remanent polarization $P_r(T)$, preceding the temperature of the paraelectric phase transition at the Curie temperature $T_C$, is noted. In the temperature range $T$ < $T_d$, the $P_r(T)$ dependence obeys a power law. In the temperature range $T_d$<$T$<$T_C$, this law is not fulfilled. The results of X-ray experiments make it possible to associate this behavior with reversible disordering at $T$<$T_d$ of an ordered domain structure formed during the polarization of piezoelectric ceramics and with its irreversible disordering in the temperature range $T_d$<$T$<$T_C$. This is due to the appearance of internal mechanical stresses in a polycrystalline ferroelectric due to irreversible depolarization of the samples at temperatures $T_d$<$T$<$T_C$.

Relaxor-based ternary Pb(${\text{In}}_{1/2}$${\text{Nb}}_{1/2}$)O₃–Pb(${\text{Mg}}_{1/3}$${\text{Nb}}_{2/3}$)O₃–PbTiO₃ (PIN–PMN–PT) single crystals and ceramics are promising candidates for high-performance electromechanical conversion devices. It is known that the domain structure and dielectric diffusion–relaxation characteristics are crucial to the excellent performances of relaxor ferroelectrics. In this work, we prepared the PIN–PMN–PT ceramics with various PIN/PMN proportions and systematically investigated their domain structure and dielectric diffusion–relaxation properties. The effect of PIN/PMN proportion on the domain size and dielectric diffusion–relaxation characteristics was also studied. The investigations showed that PIN–PMN–PT ceramics presented multi-type domain patterns comprising irregular island domains and regular lamellar domains. Moreover, the dependent relations of PIN/PMN proportions on the dielectric diffusion and domain size indicated that the PIN composition has a stronger lattice distortion than PMN composition; increasing the PIN proportion can enhance the dielectric diffusion and decrease the domain size. Our results could deepen the understanding of structure–property relationships of multicomponent relaxor ferroelectrics and guide the design and exploration of new high-performance ferroelectric materials.

The paper reports results on the complex study on ferroelectric ceramics that represent solid solutions containing components with a perovskite-type or columbite-type structure. Solid solutions of a three-component (1$-x-y$)${\text{NaNbO}}_3-x$${\text{KNbO}}_3-y$CdNb₂O₆ system are manufactured at $x$ = 0.05–0.20 and $y$ = 0.10. Domain structures in ceramic grains are studied. The consistency between experimental and calculated results is examined for coexisting phases split into non-180${}^{\circ }$ domains (mechanical twins) in the solid solution with $x$ = 0.15. A correlation between the internal structure (crystal, domain, granular, and defect) and fundamental electromechanical and polarization properties is stated for the studied three-component solid solutions.

In this report, the processes of texture formation in grain-oriented ferroelectric ceramics based on layer-structured ferroelectric Bi₄Ti₃O₂ (LSBT) prepared by hot forging method are considered. The microstructural and X-ray methods revealed the axial textured formation in ferroelectric ceramic that are used to estimate the orientation factor of ceramics. For the first time, the domain structure changes when poling the anisotropic ferroelectric ceramics are investigated. The anisotropy of electromechanical, piezoelectric and ferroelectric properties of ferroelectric ceramics due to the crystal texture existence in it is studied. The aim of this study is to study the processes of crystalline texture formation in polycrystalline BLSF and to establish the dependence of the electrophysical properties of ceramics on the degree of texturing. Ceramics were textured using the hot stamping (HS) method developed at the Research Institute of Physics. The mechanism of the method is that the workpiece is subjected to uniaxial pressure and free radial deformation occurs due to the plastic flow of the material until the workpiece fills the free volume of the mold, which is created by placing the workpiece in the mold with a gap. The study of the microstructure of ceramics showed that an increase in the firing temperature in the range 950–1050${}^{\circ }$C causes a sharp decrease in porosity and increases the density to 7.95 g/${\mathrm{\text{cm}}}^3$, which is 98% of theoretical. An X-ray analysis was performed and microstructural studies were carried out, which revealed the formation of an axial texture in ceramics. The features of the switching processes of textured ceramics are revealed. The characteristics of the polarization switching of ceramics in the directions parallel and perpendicular ($\perp$) of the pressure axis during hot processing were obtained from the dielectric hysteresis $P$($E$) loops, i.e., axis axial texture. The $\perp$-cut ceramics are characterized by a more complete polarization switching, which is associated with the additional orientation of the (001) crystallographic planes in the textured material, as well as the presence of a threshold switching field. In the temperature range from -196 to + 600${}^{\circ }$C, the anisotropy of the electro physical properties of ceramics due to the presence of a crystalline texture in it was studied. The dielectric constant, electrical conductivity, piezoelectric and elastic coefficients were measured for sections of ceramics of different orientations relative to the axis of the texture. The anisotropy of the dielectric constant and electrical conductivity manifests itself weakly at room temperature and increases sharply when approaching the Curie temperature. In the temperature range +20–400${}^{\circ }$C, the high thermal stability of the piezoelectric module $d_{33}$, measured by the quasistatic method, was established.

Ferroelectric materials are widely used in the applications of electronic devices due to their robust spontaneous polarization. The surface roughness of ferroelectric thin films, which is closely related to the morphology, can play an important role in determining the ferroelectric domain structures. In this work, we have investigated the influence of annealing conditions on the surface morphology of epitaxial BiFeO₃ and SrRuO₃ thin films prepared by pulsed laser deposition on SrTiO₃ (001) substrates. It is found that the morphology of the thin films is sensitive to the annealing time and cooling rate, and the corresponding surface roughness decreases with increasing annealing time and decreasing cooling rate. In addition, the ferroelectric domain structures of BiFeO₃ films have been investigated by piezoelectric force microscopy, which shows a significant improvement in domain size and reverse piezoelectric response in the thin films with decreasing surface roughness. This work provides a simple way to predict and improve the ferroelectric domain structures by in situ annealing.

Due to the strong magneto-elastic coupling in ferromagnetic/ferroelectric heterostructures and the potential applications in low-power magnetoelectric nanodevices, ferroelastic domains and the corresponding dynamic evolution under external stimuli have attracted intense research interest. Using pulsed laser deposition method, we have successfully grown layered-perovskite Bi₂WO₆ thin films on SrTiO₃ (001) substrates. Interestingly, for the as-grown thin films with step-flow morphology, the relationship between ferroelastic domain number and size shows a normal distribution, which is similar to the Boltzman distribution for confined gas molecules at equilibrium. In addition, with post-annealing, the thin films with as-grown island-like morphology can be optimized for layered morphology, and the initial small ferroelastic domains can grow into large domains. This study provides an effective strategy for ferroelastic domain engineering, which can be applied for the design of multiferroic heterostructures and low-power nanodevices.

In this paper, we present the study of the shape change on the polar surface and in the bulk of the walls of lamellar domains as a result of local switching by focused ion beam. Periodical lamellar domain structures (PDS) are created alternatively by two methods: (i) electric-field poling using photolithographically defined electrodes and (ii) ion beam poling. The dot irradiation of Z${}^{+}$ areas near the walls of lamellar domains leads to the formation of faceted or rounded hexagonal domains. For e-field PDS additional formation of nanodomain ensembles was observed. We have revealed two types of domain wall shape changes induced by irradiation: (1) merging of the hexagonal domain with the domain wall for Z${}^{+}$ areas; (2) formation of rounded distortion of the domain wall for Z⁻ areas. For Z${}^{+}$ areas irradiation, the domain wall distortion was described by a simple model of independent growth of isolated domain with its subsequent merging with a static domain wall. For Z⁻ surface irradiation, the domain wall shift increases linearly with the distance between the irradiation dot and the wall. It was revealed that the merging between the growing hexagonal pyramid domain and lamellar domain can be obtained in the bulk even for absence of merging at the surface. All obtained results have been explained within a kinetic approach to the domain wall motion by step generation. The switching field consists of inputs produced by: (i) the charges injected during dot irradiation into the photoresist layer and crystal bulk, (ii) the charges injected during the creation of i-beam PDS, (iii) the depolarization fields. The transition of the shapes of isolated domains and wall distortions from faceted to rounded ones with field increase was attributed to the transition from determined step generation to stochastic one.

FeNi films were prepared by oblique deposition onto glass substrate using magnetron sputtering deposition technique. The deposition was carried out on a rotating or nonrotating substrate with or without a constant magnetic field applied parallel to the substrate plane. The magnetic properties of the samples were measured by a magneto-optical Kerr effect at room temperature. All films had in-plane uniaxial magnetic anisotropy. The presence of in-plane magnetic anisotropy was also confirmed by the features of the domain structure. The main factor determining the orientation of the induced anisotropy axis of films was the magnetic field applied during deposition.