Domain configuration in epitaxial antiferroelectric films has been studied by X-ray nanoscopy, with the extraction of information about the domain sizes beyond the beam-size limit. The objective of this article is to understand how film thickness (the cases of 50 and 1000 nm are explored) and temperature (20 and 200°C) affect the nanodomain configuration of PbZrO 3 /SrRuO 3 /SrTiO 3 thin films. It is found that the majority of antiferroelectric domains in both films are too small to be directly mappable, because many of them are simultaneously illuminated by the nanobeam (60 × 100 nm) most of the time. Nevertheless, these small sizes can be studied by analysing the diffraction peak width, which is, in the simplest approximation, inversely proportional to the domain size. With this approach it is identified that the characteristic (most probable) domain size does not depend on the film thickness and is ∼13 nm, while the scarcer larger domains do depend on it. An increase of the temperature to 200°C (just below the nominal antiferroelectric-to-cubic transition temperature) results in a slight increase in the characteristic size. These results are compared with those in ferroelectric films, where domain sizes are pronouncedly thickness dependent, and the relevant methodological question on the possibility of neglecting the interference of X-ray waves scattered by different nanodomains in the nanodomain assembly is also discussed.

Control of domain and domain wall configurations in antiferroelectrics is a necessary step towards practical use of new functionalities based on polar domain wall structures. Here we propose and demonstrate a domain engineering scheme that provides an antiferroelectric state with only one type of orientational domains and one type of walls. We demonstrate with in situ synchrotron diffraction experiment that in a material, where the transition from the high-symmetry nonpolar phase to that antiferroelectric occurs via crossing an intermediate, once the transition is passed under a moderate electric field, the final antiferroelectric domain state can be fully controlled. A theoretical analysis shows that such a phenomenon can be explained in terms of biquadratic coupling between the polarization and antiferroelectric order parameter. This analysis also suggests that the electric-field control of the antiferroelectric state may be possible in a more general case where the intermediate ferroelectric state is absent. Anisotropy of lattice excitations in the intermediate polar phase under electric field is uncovered by an inelastic x-ray scattering experiment, which indicates that lattice instability is a driving force of transformation towards antiferroelectric phase despite of a strong first character of the transition.

Detailed study of the X-ray diffuse scattering in the paraelectric phase of the PbZr0.985Ti0.015O3 was carried out. We concentrated on the analysis of the scattering peculiarities in the vicinities of M- and R- points of the Brillouin zone. We have observed a critical increase of the diffuse scattering at the position Q approximate to (0.47+h 0.53+k l) slightly aside of M point on cooling to the intermediate phase. We attribute observed critical scattering to a mixed mode containing both oxygen octahedral tilts and antiparallel cationic displacements. Tentative conclusion is made describing earlier reported complicated set of the satellite peaks around M-point as the result of the soft-mode driven incommensurate phase transition.

This paper presents the results of X-ray diffraction studies on a single crystal of lead zirconate titanate PbZr0.993Ti0.007O3 in the region of existence of an intermediate ferroelectric phase. In addition to the known superstructure reflections of the M type qM = $$\left\{ {\frac{1}{2},\frac{1}{2},0} \right\}$$ and the first-order satellite reflections qM + {δ, δ, δ}, unknown second-order satellites have been observed near qM and near the Bragg reflections. Structural model of regular system of antiphase domains is used for diffraction calculation. The model is shown to describe the first- and second-orders satellite reflections in the vicinity of qM, but it cannot explain the appearance of satellites around the main Bragg peaks. A possible origin of the system of the superstructures observed in the intermediate phase is discussed.

We report the high-temperature and high-pressure single-crystal x-ray diffraction study of PbHfO3. The increase of pressure enables an additional intermediate phase, located between the cubic and incommensurate phases, and characterized by superstructure reflections indicating the presence of anti-phase oxygen octahedral tilts. The temperature-dependent diffuse peak at an incommensurate position is much better pronounced at higher pressures (~ 2 GPa) than at lower pressures (~ 1.1 GPa), which we interpret as enhancing of the incommensurate soft mode on pressure increase. Several peculiarities in the behavior of superstructural reflections at M- and X- points are reported and discussed.

An Erratum to this paper has been published: https://doi.org/10.1134/S1063783423900018

Results of X-ray diffraction in the intermediate ferroelectric phase of single crystal PbZr$_{0.993}$Ti$_{0.007}$O$_{3}$ are presented. Existence of M-type superstructures $q_{M}$ = \{$\frac{1}{2}$, $\frac{1}{2}$, 0\} and satellites around them, $q_{M}+\{\delta,\delta,\delta\}$, is confirmed. For the first time second order satellites $\{2\delta,2\delta,2\delta\}$ have been observed in the vicinity of $q_{M}$ and fundamental Bragg peaks. Structural model of regular system of antiphase domains is used for diffraction calculation. Calculated pattern includes M-type superstructures as well as first and second order satellites around $q_{M}$. It is shown that second order satellites around fundamental Bragg peaks could not be reproduced in the context of this model. The possible origin of the system of the superstructure reflection observed in the intermediate phase is discussed.

Phase transitions in lead hafnate (PbHfO3) at high temperature and high pressure were studied by single-crystal diffraction and diffuse scattering of synchrotron radiation, using heated diamond anvil cell. Measurements were carried out in the temperature range 182 ° С

We have studied temperature-induced phase transitions in PbZrO3 thin films by X-ray diffraction. By tracing the temperature dependence of superstructure reflections we show that the onset of antiferroelectric ordering takes place highly continuously on cooling and another, presumably ferroelectric phase is present at high temperatures, between the antiferroelectric and cubic phases. To clarify the possible reason for this behavior, we have investigated the X-ray diffraction profile with momentum transfer along the normal to the film surface and carried out the relevant simulation using the formalism of scattering by inhomogeneously deformed sample. From the analysis it follows that the near-interface layer is effectively compressed along the normal to the film. We associate this observation with the presence of dislocations through which the film is relaxed. The results suggest that the reasons for the phase transition sequence modification in thin films can be associated with inhomogeneous distribution of stress and defects in the near-interface area.

Preliminary results of inelastic neutron scattering in chemically ordered Pb(Sc 1/2 Nb 1 / 2 )O 3 (PSN) are reported. It is shown that neutron spectra, obtained around 220 node in $\left[ {1\bar 10} \right]$ direction, are characterised by intense central peak and broad phonon resonances at all studied temperatures. It has been found that TO in-plane polarised phonons do not demonstrate any softening. On the contrary, clear growth of TO phonon energy was detected for all temperatures. Intensity of the central peak continuously grows on cooling. Observed critical dynamics scenario completely differs from the expected one for relaxor or ferroelectric material. We believe our observations could bring new insights in the understanding of the microscopic origin of the relaxor phenomena.

The review deals with studies carried out at the BM01 diffraction beam line of the European Synchrotron Radiation Facility. X-ray diffraction analysis of single-crystal proton conductors demonstrates the possibilities of a precise diffraction experiment in which phase transitions associated with the release of crystallization water and transformation of the network of hydrogen contacts are investigated. Scanning of reciprocal space with the help of a 2D detector enables us to determine the new phase symmetry in a thin-film multiferroic sample based on bismuth ferrite (the given phase is stable only under thin-film conditions). A combination of Bragg and diffusion scattering processes is employed to investigate the interdependence between the structure and dynamics of a crystal lattice and the physical properties of a relaxor material with a perovskite-like structure. The complementarity and synergy of neutron and synchrotron experiments are demonstrated using the combined study of materials from the manganese-silicide group, which has revealed a nontrivial relationship between magnetic and crystallographic chiralities in noncollinear magnets. Although the given review is limited to only a few experiments carried out by Russian scientists at the BM01 beam line, they still illustrate a variety of problems that can be solved using a modern diffraction station where the bending magnet of a third-generation synchrotron is employed as the synchrotron radiation source.

AbstractThe technique of studying the synchrotron radiation scattering on single crystals over wide temperature range using an original miniature device for applying an electric field to a sample is described. A specific feature of the device is the possibility of its application with various heating and cooling systems. The technique was used at BM01 beamline at the European Synchrotron Radiation Facility (ESRF) for the study of the influence of electric field on the processes of structural transformation in lead zirconate–titanate single crystal with a low titanium concentration. The efficiency of the technique proposed in this work is demonstrated and the results of the preliminary analysis of the results are presented.

The results of the X-ray diffuse scattering (DS) measurements of the Zr-rich PbZrO\(_{3}\) - PbTiO\(_{3}\) solid solution PbZr\(_{0.985}\)Ti\(_{0.015}\)O\(_3\) (PZT1.5) are presented. Measurements were performed in zero electric field and in applied electric field E = 5 kV / cm. In the antiferroelectric phase diffuse scattering streaks around \(\varSigma \) superstructure peaks \((h+\frac{1}{4}~k+\frac{1}{4}~l)\) were found and interpreted as a scattering on ferroelectric antiphase domain walls. This conclusion is corroborated by the observation of a strong influence of the electric field on these streaks. Reported results are important for the prospective application of the antiferroelectrics as the basis for the high-density non-volatile memory devices.

Antiferroelectric PbZrO3 epitaxial thin film with thickness of 50nm grown on the SrTiO3 substrate with SrRuO3 buffer layer was studied by Grazing incidence X-ray diffraction in a wide range of temperatures. Apart from the superstructure reflections characteristic for the antiferroelectric phase, we identify the reflections with pseudocubic coordinates of the form (H+0.5, K+0.5, L). This indicates the presence of structures having orthorhombic symmetry as an effect of anti-phase Pb atoms displacements, which are apparently similar to the ones previously proposed for the rhombohedral high-temperature phase in PbZrxTi1-xO3. For these structures only the domain orientations with displacements parallel to the surface are observed in contrast to the antiferroelectric domains where the parallel to surface Pb displacements are absent. The antiferroelectric phase coexists with the one characterized by (H+0.5, K+0.5, L) reflections in a broad temperature range with the maximal amount of the latter being present at T=150 degrees C.

Antiferroelectric-based crystals are key ingredients of modern piezoelectric and optoelectronic materials as well as materials for applications in energy storage and nonvolatile memory devices. Nanoscale modulated phases are commonly found in antiferroelectrics doped with a small concentration of ferroelectric material. Lattice dynamics in the paraelectric phase of antiferroelectrics provides an important tool for assessing the mechanisms of formation of modulated phases. We present here the results of the analysis of the phonon spectra of the antiferroelectric perovskite lead hafnate in the frames of the shell model and show that a highly anisotropic polarizability of oxygen may play an important role in conditioning the tendency towards the nanoscale modulations.

Lead hafnate single crystals were characterized using single crystal x-ray diffraction under simultaneous application of hydrostatic pressure and high temperatures. The information on the structure of two intermediate phases, situated between antiferroelectric and paraelectric phases in the pressure-temperature phase diagram, has been obtained. The lower-temperature intermediate phase is characterized by incommensurate displacive modulations in Pb sublattice. The higher-temperature intermediate phase is characterized by oxygen framework distortion, primarily in the form of anti-phase tilts of the oxygen octahedra, which is also present in the lower-temperature intermediate phase.

The technique of studying the synchrotron radiation scattering on single crystals over wide temperature range using an original miniature device for applying an electric field to a sample is described. A specific feature of the device is the possibility of its application with various heating and cooling systems. The technique was used at BM01 beamline at the European Synchrotron Radiation Facility (ESRF) for the study of the influence of electric field on the processes of structural transformation in lead zirconate–titanate single crystal with a low titanium concentration. The efficiency of the technique proposed in this work is demonstrated and the results of the preliminary analysis of the results are presented.