International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This work presents an overview of sol–gel-derived oxide materials and their relevance to optical, photonic and photovoltaic applications, followed by an experimental study of ZrO₂–Al₂O₃–Sm₂O₃ thin films deposited on glass substrates. Historical developments of the sol–gel process, beginning with early investigations on silica gels in the 19th century, are outlined together with advancements in optical glasses, anti-reflective coatings, and rare-earth-doped systems. Recent progress in functional materials—including boron-, tellurium- and rare-earth-containing glasses, luminescent oxide systems, and sol–gel-derived zirconia-based coatings—is discussed to highlight their structural, optical and radiation-shielding capabilities.
In the present study, multilayer ZrO₂–Al₂O₃–Sm₂O₃ coatings were prepared via the sol–gel method combined with dip-coating, and subsequently thermally treated at 420 °C. Optical characterization (UV–VIS–NIR) revealed changes in transmittance and reflectance linked to film composition and thickness, while X-ray diffraction confirmed their predominantly amorphous structure at the applied heat-treatment temperature. SEM and EDS analyses provided insight into surface morphology and elemental distribution within the films. The results demonstrate that increasing Al₂O₃ content influences coating porosity and thickness, while Sm₂O₃ contributes luminescent functionality and potential reduction of optical reflection in key solar spectral regions. These findings indicate that ZrO₂–Al₂O₃–Sm₂O₃ thin films are promising candidates for protective and functional coatings in photovoltaic applications, where enhanced light harvesting and improved surface properties are essential.

Corrosion remains a major limitation for the long-term use of aluminum alloys such as A356, particularly in chloride-rich environments. Although traditional chromate coatings provide effective protection, their toxicity necessitates environmentally friendly alternatives. In this study, a composite ZrO2–Al2O3–Sm2O3 coating was synthesized via a sol-gel method and deposited on A356 alloy using dip-coating. The precursor system was formulated from zirconyl chloride, samarium oxide, and aluminum oxide, stabilized with acetylacetone and acetic acid at pH 0.5 to ensure homogeneous film formation. The coated samples were thermally treated at 400 °C to obtain dense oxide layers. Corrosion resistance was assessed under neutral salt spray conditions (5% NaCl, 35 °C, 648 h) according to BDS EN ISO 9227:2023. Comparison between uncoated A356, binary Al–Zr (ADZ), and ternary Sm–Al–Zr (SADZ) coatings demonstrated a clear performance improvement with increasing film complexity. While ADZ coatings reduced surface damage relative to the bare alloy, the SADZ films exhibited the lowest amount of corrosion products, minimal surface darkening, and significantly reduced pitting. The enhanced performance is attributed to the synergistic effect of the three oxides: ZrO₂ provides chemical stability, Al2O3 increases layer density, and Sm₂O₃ contributes active corrosion inhibition.
Overall, the ZrO2–Al2O3–Sm2O3 composite film offers a promising non-chromate protective system for improving the long-term corrosion resistance of A356 aluminum alloy.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Sm2O3), applied by the sol-gel method on glass slides. This study attempts to improve the overall efficiency of a photovoltaic solar panel by using a Sm2O3 doped ZrO2 (SDZ)-based coating. The optical characterization and phase composition of the obtained experimental samples were investigated using UVVIS- NIR, XRD and XRF methods. The coatings are nanocrystalline according to XRD and XRF analyzes and show transmittance close to that of pure glass when tested with a UV–VIS–NIR spectrophotometer The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting selfcleaning coatings, potentially applicable to photovoltaic panels.

Thin coatings of aluminum oxide (Al2O3), zirconium oxide (ZrO2) and samarium oxide (Sm2O3) on aluminum alloy Al7SiMg (A356) were prepared by sol-gel method and immersion technique. The materials were characterized in detail by X-ray diffraction. The luminescent properties at room temperature were also investigated. Luminescence analysis showed that the Al2O3 coating containing ZrO2 exhibits broad excitation and emission bands, peaking at 328 nm and 392 nm, respectively. Photoluminescence data for the Al2O3 coating containing ZrO2 and Sm2O3 indicated effective excitation at 404 nm and strong broadband emission, which is due to the co-emission of ZrO2 and Sm2O3. Chromaticity coordinate analysis revealed that Al2O3 coating containing ZrO2 and Al2O3 coating containing ZrO2 and Sm₂ O₃ emit in the blue-purple and pale pink regions, respectively.The chromaticity coordinates, color purity and CIE (Commission Internationale de L’Eclairage) color-correlated temperature were determined.

Thin coatings of zirconia oxide (ZrO2) and samarium oxide (Sm2O3) on glass have been prepared by using sol-gel method and dip coating technique. Materials were characterized in detail by X-ray diffraction. The luminescent properties at room temperature were also investigated. Excitation and emission spectra of ZrO2 coating consists of broad bands with maximums at 318 and 365 nm respectively.
The photoluminescence measurements of samarium coating suggest that can be efficiently excited with 700 nm and consist of emission bands centered at 567, 603, 639 and 707 nm, consistent with characteristic Sm3+ transitions. The CIE (Commission Internationale de L’Eclairage) chromatic coordinates, color purity and color correlated temperature were determined.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Eu2O3), applied by the solgel method on glass slides. This study attempts to improve the overall efficiency of a photovoltaic solar panel by using a ZrO2-based coating, with Y2O3 and addition of Eu2O3. The optical characterization and phase composition of the obtained experimental samples were investigated using UV-VIS-NIR, XRD and XRF methods. The coatings are nanocrystalline according to XRD and XRF analyzes and show transmittance close to that of pure glass when tested with a UV–VIS–NIR spectrophotometer The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Eu2O3), applied by the sol-gel method on glass slides. The luminescence of the obtained thin layers of different ratios of the compositions were investigated. A strong emission from the 5D0 level of Eu3+ ions was registered under near UV (392 nm) excitation using the 7F0 → 5L6 transition. The values of the integrated fluorescence intensity ratio R (5D0→7F2)/(5D0→7F1) was calculated to give information about the degree of asymmetry in the vicinity around the active ions, suggesting a location of Eu3+ in non-centrosymmetric sites. The highest Eu3+ luminescence is observed in sample with 3 layers coating. The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

A solution was synthesized in a system ZrO2-CeO2 by sol-gel synthesis and deposited by the immersion method. The pretreated Nb substrate was treated with sulfuric acid and absolute alcohol solutions. Layering was in three stages. The sample was heat treated at 500°C. The obtained results are characterized by XRD, XPS, CEM analyzes.

In view of the practical applications of the piezoelectric ceramics produced from barium titanate (BaTiO3) and barium stannate (BaSnO3), (the BT-BS system), the dielectric behavior of such materials was studied. The starting components (powder of both BaTiO3 and BaSnO3) were synthesizedand structurally characterized in аdvance. Bulk samples of BT-BS (formed as tablets with addition of PVA plasticizer) were prepared using the sol-gel method by varying the BT-BS composition percentage. The samples were characterized by complex electrical impedance spectroscopy and dielectric spectroscopy in the frequency range from 0.1 Hz to 1 MHz. As compared to BaTiO3, an increase with at least 50 % was measured for the value of the room-temperature dielectric constant (e′ – the real part of the dielectric permittivity) of the BT-BS samples containing 15 wt% BaSnO3. In contrast, the 50 wt% content of BaSnO3 led to a decrease of ′ value of BT-BS by a factor of 3.5, due to relatively low e′ value of BaSnO3. Analyses of the frequency spectra of complex electrical impedance and complex dielectric permittivity revealed the dielectric relaxational behavior of the BaTiO3+BaSnO3 system. The results obtained for ′ of BT-BS dielectrics as a function of the temperature were correlated with the data from structural studies. In particular, a specific enhancement of e′ was observed in temperature range around 120C for the BT-BS samples containing 15 wt% BaSnO3. Corresponding conclusions were done. The effects observed show that the synthesized BaTiO3-BaSnO3 ceramics are promising materials for piezoelectric and dielectric applications, e.g., in energy storage devices.

The aim of the present work is to study the characteristics and conditions of obtaining thin films in the BaTiO3–BaSnO3 system, deposited by the sol-gel method on monolithic multilayer samples. In laboratory conditions, the structure, phase composition, micromorphology, electrophysical parameters of the prepared experimental samples were studied. The existing possibilities for optimizing the applied technological regime for the synthesis and surface deposition of thin-layer coatings with set characteristics have been analyzed.

Dip coating is a common liquid deposition technique used in research and also for industrial production to produce polymeric, hybrid, and inorganic thin films of controlled thickness. During liquid deposition, the substrate withdrawal rate allows, in principle, easy tuning of the deposited film thickness. However, experimentally, unexplained thickness irreproducibility or strong fluctuations of sol-gel films are often observed when coating large substrates, which is a critical problem for optical coatings such as anti-reflective/reflective coatings. In this study, we present improved coatings obtained by sol gel-like multilayer structures composed of ZrO2-Y2O3 coating. The phase composition and morphology were analyzed by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) suitable for characterizing the surface properties of the obtained materials.

The present publication is aimed at obtaining a stable sol from ZrO2 stabilized with Y2O3. The substrate on which the layers are deposited was developed by a team from Russia and is intermetalite with a layered structure Nb30Ti/Al. Deposition was performed by spinning with a Spin Coater Ossila L2001A3. The deposition sequence of the layers lasts 30 seconds. The finished carrier is dried at 120°C in an oven. It is heated in a laboratory furnace at 350oC. The results were characterized by XRD and SEM analyzes.