Valeriy M. Kondratev

A CsPbBr ₃ -coated ZnO microprism supports robust whispering gallery lasing near 537 nm with a Q -factor above 10 ³ via a decoupled cavity design.

The nanomechanical properties of lead-halide perovskites are vital for flexible electronics but are challenging to measure directly in individual nanocrystals. Here, we present an original experimental method based on atomic force microscopy for the direct and precise measurement of Young's modulus for single CsPbX3 (X = Br, Cl) nanoparticles via uniaxial compression. The method is based on the measurement of the loading curves followed by their simulations, with a precise reproduction of the nanoparticle and probe tip's shapes. It revealed an apparent size-dependent behavior in the measured Young's moduli, which can be attributed to geometric and instrumental factors of the experiment. Subsequent multi-physical simulation of the experiment revealed more accurate elastic moduli of 16 and 24 GPa for CsPbBr3 and CsPbCl3, respectively. In addition, our calculations based on density functional theory demonstrate that mechanical compression induces bandgap narrowing, particularly strong in CsPbCl3. The study establishes a direct correlation between mechanical stress and electronic structure in perovskite nanomaterials, providing a foundation for the development of compression-resistant and strain-engineered optoelectronic devices.

Gallium phosphide (GaP) is emerging as a highly compelling platform for next‐generation photonic integrated circuits (PICs) due to its unique combination of a high refractive index, strong nonlinearities, and a broad transparency window extending into the visible spectrum where silicon (Si) is opaque. The development of this platform hinges on the realization of fundamental building blocks, with the directional coupler being an indispensable component for advanced circuits. In this work, we report the comprehensive design, fabrication, and experimental characterization of a 2 × 2 directional coupler constructed from mechanically assembled GaP nanowires. The fabricated devices exhibit the characteristic wavelength‐dependent power exchange between adjacent waveguides. We introduce and validate a computationally efficient 2D design methodology that accurately predicts device performance, significantly reducing the optimization cost compared to full 3D simulations. Critically, we provide a proof‐of‐concept for mechanical control over optical properties by activating the coupling effect in situ through physical manipulation of the nanowire interaction length. This result leverages the remarkable elasticity of GaP nanowires and establishes a foundational step toward complex, reconfigurable PICs for future applications in quantum information processing, nonlinear optics, and sensing.

MXenes, a class of 2D materials that have emerged recently, are known for their unique properties and broad applicability. They are traditionally synthesized from MAX phases by etching A‐group atoms, usually Al. Here, the controlled transformation of residual aluminum is demonstrated, as both MAX‐phase component and pervasive impurity in MXene synthesis, into a functional diagnostic asset. Through laser irradiation, Al is photooxidized in situ, forming embedded Al ₂ O ₃ :Cr ³ ⁺ centers with ruby line luminescence with a peak width of about 1 nm by laser irradiation of individual grains of Cr ₂ AlC. The luminescence emerges due to Al oxidation with Cr doping. It is also demonstrated that the ruby luminescence is an unexpectedly universal phenomenon which occurs even in Cr‐free MAX‐phases and MXenes, owing to the incomplete Al etching and slight Cr doping of natural origin. Discovered sensitivity of ruby luminescence intensity to residual Al enables rapid, minimally destructive, and spatially resolved control of etching quality, essential for the industrial maturation of MXenes. Furthermore, the capacity to locally generate integrated optical probes opens new pathways for in operando diagnostics in MXene‐based devices.

In this manuscript, we present a study on the optical properties of ZnO NWs and microcrystals synthesized via hydrothermal method. The NWs were characterized by low-temperature photoluminescence spectroscopy, which revealed resonance modes indicating random lasing behavior mediated by scattering from misoriented nanowires. The spectral position of the resonance modes suggests lasing in the P-band region of exciton–exciton interaction. Our results also indicate a correlation between the surface density of nanostructures and the peak emission intensity. In addition, optically behavior of individual ZnO microprisms integrated in with a thin perovskite active layer were investigated by room-temperature microphotoluminescence spectroscopy. The results indicate that the ZnO microprisms are efficient optical cavities. Overall, our findings demonstrate the potential of hydrothermal synthesis for the fabrication of efficient ZnO-based light-emitting devices.

Cells can break and chemically modify nanowires allowing imaging, transfection and assay development.

Introduction. Nanomaterials based on binary and multicomponent oxides are of interest for the development of catalysts, photocatalysts, gas sensors, solar cells, as well as in other fields. The most effective methods to produce oxide systems of various compositions are those of chemical co-deposition, as well as two-stage approaches.Aim. To develop sensor nanomaterials based on ZnO, Zn–Fe–O, and Zn–Sn–O ternary oxide nanosystems, as well as to develop methods for assessing their properties.Materials and methods. ZnO and ZnFe2O4 nanopowders were synthesized by chemical coprecipitation, and ZnFe₂O₄ and Zn₂SnO₄ nanostructures were produced by modifying ZnO nanowires. The surface chemical composition and microstructure were studied using scanning electron microscopy, backscattered electron diffraction, and Xray photoelectron spectroscopy. The sensor responses of the samples to vapors of organic solvents were analyzed.Results. The response value of zinc oxide and zinc ferrite samples synthesized by chemical coprecipitation was found to be 2–4 orders of magnitude higher than that of modified zinc oxide nanowires. The formation of ternary oxide nanostructures led to an increase in the sensor response of zinc oxide nanowires. This effect can be explained by the formation of adsorption sites of various types during formation of such systems. The samples produced by chemical coprecipitation showed an extremely high sensor response. This may be due to the formation of fractal structures at the percolation threshold.Conclusion. ZnO and ZnFe₂O₄ oxide nanostructures produced by chemical coprecipitation exhibit a high sensor response to acetone and ethanol vapors. Methods for the formation of multicomponent oxide systems with improved sensor properties compared to the original zinc oxide nanowires were developed. The resultant sensor nanomaterials are promising for use as sensitive layers of gas sensors for detecting organic solvent vapors.

Carbon dots (CDs) are promising nanostructures in the field of photonics owing to the ease of fabrication, tunable and efficient emission. Gallium phosphide (GaP) nanowires are known for high surface area, optical density, waveguiding, resonant optical properties but lacking the luminescence due to the indirect bandgap. Here, hybrid photonic structures – GaP nanowires decorated with the CDs are fabricated and studied. Feasible drop‐casting deposition technique allows fabrication of dense vertical structures exhibiting efficient photoluminescence. Deposition of the CDs over the nanowires does not affect their luminescent properties demonstrating tolerance of the approach toward the surface aggregation. Tuning of the emission spectrum is obtained via variation of the excitation wavelength and CDs’ synthesis protocol. The structures emitting throughout the visible range are obtained. Analysis of the photoluminescence of an individual structure demonstrates the most intense and fast recombination processes at the ends of a nanowire. It is shown that the luminescence of the CDs’ covering a nanowire acting as a Fabry–Perot cavity is enhanced up to a factor of 3 governed by the Purcell effect. The obtained results unveil a path for fabrication of novel photonic devices via decoration of optically dense nanowires with CDs for enhanced and directed broadband emission.