№ 4 (2025)

Despite the large number of already published articles on the topic of ferroelectric properties of Hf₀.₅Zr₀.₅O₂ (HZO), this material still attracts enormous attention from the scientific community due to its potential for creating competitive non-volatile HZO-based memory devices compatible with modern silicon technology. Among the challenges in developing industrial-scale technology for such devices is the instability of the residual polarization of the ferroelectric during repeated switching by an external electric field. In particular, during the initial stages of such “cycling,” a significant increase in residual polarization is typically observed (the so-called “wake-up” effect), followed—after a certain number of cycles—by its decline (the so-called “fatigue” effect). The question of which processes cause this instability remains under debate. Using a previously developed methodology for analyzing the phase composition of ultrathin HZO layers via the NEXAFS synchrotron radiation method, it has been shown that in capacitors based on TiN/HZO/TiN structures, the “wake-up” effect observed during the first 10⁵ switching cycles can be explained by an increase in the relative content of the polar orthorhombic phase in HZO due to a reduction in the content of the “parasitic” tetragonal phase. The results obtained confirm that an electric field-stimulated structural phase transition in the films is one of the mechanisms explaining the evolution of the functional properties of HZO-based ferroelectric memory elements throughout their service life.

In this work, nanopowders of the Bi₁–xBaₓFeO₃ system (x = 0, 0.10, 0.20) were synthesized using the combustion method of nitrate-organic precursors. The effect of doping bismuth ferrite (BiFeO₃) with barium (Ba²⁺) ions on the morphology, crystal structure, and photocatalytic activity of the material was studied. X-ray diffraction analysis showed that all samples crystallize in a rhombohedrally distorted perovskite structure with the R3c space group. Doping with barium led to a significant decrease in crystallite size, as well as distortion of the crystal lattice. In the case of 20% substitution, the formation of a BaCO₃ impurity was observed, which was also confirmed by Raman spectroscopy. It was shown that the introduction of barium results in a more porous texture and a significant increase in the specific surface area of the material. The original BiFeO₃ demonstrated extremely low efficiency in the photocatalytic decomposition of methylene blue compared to photolysis. However, barium doping significantly improved the photocatalytic performance: at 20% Ba substitution, methylene blue decomposition reached 99% within 1 hour.

The parameters of electromagnetic radiation that should be generated during guiding of accelerated electrons (extended sliding interaction of accelerated electrons with a dielectric surface) pressed to the surface of a dielectric plate by an external electric field are calculated. The model of the effect (guiding) is proposed based on an analysis of the solution to the Hamilton equation for the motion of electrons in an external electric field and in an electrostatic field created by electrons deposited on the surface of a dielectric plate. Superposition of these fields leads to the fact that during guiding electrons experience transverse vibrations relative to the surface of the plate, i.e. acquire lateral acceleration. And this, as is known, should lead to the generation of electromagnetic radiation, the frequency and intensity of which depend on the electron energy, similar to the radiation of undulators and wigglers. Calculations show that when electrons are guided, radiation should be generated depending on their energy. The maximum of its intensity is in the region from IR to the radio frequency range.