Journal of Sol-Gel Science and Technology最新文献

In this investigation, the Yb_0.7Eu_0.3FeO₃ nanoparticles were prepared via the sol-gel method and optimized the calcined temperature (800 °C, 850 °C and 900 °C) to revels the optimized physical performance. X-ray diffraction (XRD) and Rietveld refinement confirmed a single-phase orthorhombic (Pnma) crystal structure with enhanced crystallinity at higher temperatures. An increase of calcination temperatures increases the crystallite size while inducing octahedral tilting and strain. The average particle size for Yb_0.7Eu_0.3FeO₃ calcined at 800, 850 and 900 °C was 152, 161 and 168 nm, respectively was observed through scanning electron microscopy (SEM). The magnetization value increased from 2.721 emu/g to 3.789 emu/g with an increase of calcination temperature from 800 °C to 900 °C for Yb_0.7Eu_0.3FeO₃ sample. Magnetic measurements indicated improved Fe³⁺–Fe³⁺superexchange interactions, with the 900 °C sample exhibiting superior magnetization. A strong red photoluminescence was observed under 532 nm excitation, dominated by the ⁵D₀ → ⁷F₂ transition of Eu³⁺, with intensity increasing alongside temperature due to improved local symmetry. X-ray photoelectron spectroscopy (XPS) confirmed the oxidation states of each ion along with ~20.12% oxygen vacancies, contributing to the observed functional behavior. The findings underscore the critical role of calcination in tuning multifunctional properties, highlighting Yb_0.7Eu_0.3FeO₃ as a promising candidate for optoelectronic and magneto-optic applications.

Hard/soft x[Sr_0.5Ba_0.5Cr_0.1Fe_11.9O₁₉]/y[(Ni_0.3Cu_0.3Zn_0.4)Fe₂O₄] (where x/y = 2:1; 1.5:1; 1:1; 1:1.5; 1:2) nanocomposites (NCs) (abbreviated x[Cr→SrBa-HF]/y[NiCuZn SF] NCs) in which Sr_0.5Ba_0.5Cr_0.1Fe_11.9O₁₉ hexaferrite (HF) is the hard (H) component and (Ni_0.3Cu_0.3Zn_0.4)Fe₂O₄ spinel ferrite (SF) is the soft (S) phase were obtained via single-pot sol-gel auto-combustion route. Both structural and morphological examinations confirmed the formation of the desired nanosized compositions with no impurity. The analysis of magnetic properties discloses ferrimagnetic-like behavior for the different NCs at both 300 and 10 K. Two-step hysteresis loops in the second quadrant of the M-H loops and two maxima in dM/dH vs. H curves are observed, revealing that the exchange couple effect is not completely achieved between the two ferrite components. M_s, M_r, and ({n}_{B}) values increase and have a maximum for x/y ~ 1.0/1.0 NCs, which start diminishing as the abundance of the SF phase further increases. On the other hand, the coercivity of NCs is found to decrease with increasing SF phase content.

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Soft/soft (S/S) Co_0.5Ni_0.5Sc_0.04In_0.04Fe_1.92O₄@MFe₂O₄ (M = Mg, Cu, Zn, Mn) nanocomposites (NCs) were fabricated using a facile one-pot sol–gel approach. The soft/soft spinel ferrite structures were confirmed via XRD powder patterns and HR-TEM. with crystallite sizes within range of 25 to 31 nm being observed. It was observed that the lattice constants fluctuated with changing of the dopant in MFe₂O₄ (M = Mg, Cu, Zn, Mn). A study investigating the impact of various MFe₂O₄ (M = Mg, Cu, Zn, Mn) ratios on the electrical and dielectric features of these NCs indicated that the Mg-substituted NC exhibits moderate conductivity with the lowest activation energy (Ea), while the Mn-substituted sample demonstrates enhanced electron hopping and reduced impedance due to mixed ionic-electronic conduction. Zn substitution introduces higher Ea and complex impedance behaviour, suggesting increased lattice distortion. These findings highlight the influence of metal ion substitutions on the electrical and dielectric characteristics of the NCs, suggesting potential applications in electronic and magnetic devices depending on the desired property profile.

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This work aimed to synthesize borate bioactive glasses (BBGs) with the composition x(CoO/SrO)-(28-x)CaO-27Na₂O-42B₂O₃-3P₂O₅ utilizing the sol-gel process. In this research, cobalt (Co) and strontium (Sr) ions were co-doped in an equimolar ratio (1:1) at varying concentrations of x = 0, 1, 2, and 3 mol%. Various techniques were employed to explore the impact of Co and Sr doping on the structural, bioactive, and antibacterial properties of the prepared samples. The bioactivity of the glass samples was assessed based on their ability to form a hydroxyapatite layer (HA) after soaking in simulated body fluid (SBF) for time intervals of 0, 7, 14, and 21 days. The Co-Sr co-doped BBGs exhibited a positive effect on HA layer formation, which was confirmed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Field emission scanning electron microscopy (FESEM) analysis. The pH values of SBF were measured using a benchtop microprocessor pH meter. An initial increase in pH was observed during the first three days, attaining a maximum value of 8.57. Subsequently, a gradual decrease was recorded, with the pH stabilizing at ~7.85 after 21 days. The antibacterial activity was assessed utilizing a well diffusion method. Among the various compositions, the sample named 1.5CoSr demonstrated the most significant antibacterial activity, exhibiting inhibition zones of 17 mm and 20 mm against E. coli and S. aureus bacteria, respectively. The study findings revealed that the 1.5CoSr sample can be considered an optimized glass composition, which is a promising candidate for bone tissue regeneration applications.

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A schematic illustration showing the preparation steps of borate based bioactive glass powder using sol-gel method

This study reports the synthesis and characterization of eco-friendly gum/Fe₃O₄ hydrogel beads for the efficient removal of methylene blue (MB) and methyl violet (MV) dyes from aqueous solutions in batch and continuous systems. The beads, characterized by SEM, FT-IR, XRD, and VSM, exhibited maximum adsorption capacities of 0.268 mmol/g for MB and 0.277 mmol/g for MV at pH 9, with removal efficiencies exceeding 97% in batch experiments. Adsorption followed the Freundlich isotherm and double-exponential kinetic model, indicating heterogeneous surface adsorption and dual-stage diffusion. Thermodynamic analysis confirmed a spontaneous, exothermic process (ΔG < 0). In fixed-bed column tests, breakthrough times were 364 min for MB and 660 min for MV, with dye removal efficiencies of 41.6% and 55.4%, respectively. The beads retained over 90% adsorption capacity after eight cycles, demonstrating excellent reusability. These findings highlight gum/Fe₃O₄ hydrogel beads as a sustainable, high-performance adsorbent for industrial wastewater treatment.

The need for significant performance and sustainable energy storage solutions is constantly increasing, which has led to sustained interest in approaches for enhancing lithium-ion battery (LIB) technology. The present review explores the significant role of anode designs in influencing the prospect of LIBs, by examining their challenges and solutions to enhance the performance of future energy storage systems. It opens new doors by emphasizing the growth of LIBs as a crucial candidate in the global shift to clean and effective energy systems, and highlights the importance of anode architecture in influencing the overall performance and lifetime of LIBs. It elaborates the discoveries and inventions that have evolved to address existing anode structural problems, such as insufficient energy density, deteriorating cycling performance, and safety concerns, in a systematic way. This includes the introduction of new anode materials, advances in nanostructured designs, and the incorporation of modern technologies to advance the complete efficiency along reliability of lithium-ion batteries. Furthermore, it emphasizes the need to recognize the underlying electrochemical principles driving anode behavior to accelerate battery technological improvements. It continues by underlining the revolutionary potential of new anode architectures, demonstrating their ability to not only fulfill growing energy storage needs but also solve the environmental and sustainability problems.

This study presents a sustainable approach for synthesizing an eco-friendly photocatalyst by functionalizing amorphous titanium dioxide (TiO₂) with a natural dye extracted from waste flowers of hollyhock (HH). The TiO₂ was prepared via a sol-gel method. The dye-functionalized TiO₂ materials were characterized usingXRD, FTIR and UV-Vis spectroscopy. The FTIR established the interaction between TiO₂ and fuctional groups of the added dye. The XRD results confirmed the amorphous nature of the pure TiO₂ and revealed broad peaks in dye doped TiO₂. The incorporated dye reduced TiO₂’s band gap from 3.4 eV to 2.09 eV, resulting in a blue absorption shift into the visible range. FTIR spectroscopy confirmed strong dye-TiO₂ interactions, while UV-Vis analysis revealed enhanced optical properties, including a higher refractive index, dielectric constant, and modified electronic transitions per Tauc’s model. The photocatalyst exhibited negligible adsorption in the dark but achieved 100% methylene blue (MB) degradation under UV light at neutral pH. The catalyst retained activity over five cycles with gradual efficiency loss. These findings demonstrate the promising ability of green waste-derived natural dyes to functionalize amorphous TiO₂ and thereby pave the way for sustainable, efficient photocatalytic applications.

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Zinc oxide (ZnO), a wide-bandgap semiconductor, exhibits tunable dielectric and electrical properties when doped with transition (e.g., Cu, Ni, Co) or alkaline-earth metals (e.g., Ca, Mg). This review examines recent studies on sol–gel synthesized doped ZnO nanoparticles, focusing on how dopant type, concentration, and synthesis conditions influence dielectric constant (ranging from ~12 to 85), dielectric loss, and AC conductivity (improved by up to 100× in some doped samples). Frequency- and temperature-dependent behaviors are discussed, with attention to space charge polarization and Maxwell–Wagner relaxation as key mechanisms. Structural factors such as crystallite size, porosity, and grain boundary effects are linked to electrical performance. The review also identifies key challenges, including dopant segregation and poor reproducibility in sol–gel synthesis, which limit scalability and device integration. Finally, it outlines data-driven approaches such as machine learning for guiding the future design of ZnO-based dielectric materials for nanoelectronics and energy storage applications.

We prepared ZrO₂ thin films by spin-coating from Zr(OC₃H₇ⁿ)₄ and ZrOCl₂·8H₂O solutions, and investigated the influence of relative humidity (R.H.) during spin-coating on their microstructure and porosity. The Zr(OC₃H₇ⁿ)₄ solutions contained either a peptizing agent (HNO₃) or a chelating agent (CH₃COCH₂COCH₃, acac), while the ZrOCl₂ solutions with or without acac were used. Spin-coating was performed on Si(100) substrates under various R.H. conditions, and the resulting precursor films were heated up to 500 °C at a rate of 5 °C/min. Field-emission scanning electron microscopic observation was made, and ellipsometry was employed to obtain refractive indices, from which porosities were calculated. The ZrO₂ films from Zr(OC₃H₇ⁿ)₄ solution with HNO₃ exhibited relatively dense microstructures and porosities as low as ~25% when deposited at R.H. as low as 20%, while they developed nanoscale crevices and had increased porosities up to ~47% when deposited at R.H. above 50%. When Zr(OC₃H₇ⁿ)₄ solution contained acac, on the other hand, the films maintained dense microstructures and porosities as low as 20% even when deposited at R.H. as high as 70%. In contrast, the films from ZrOCl₂ solutions consistently showed dense microstructures and porosities as low as 13%, regardless of R.H. during deposition or acac addition. These results suggest that, to obtain dense ZrO₂ films with low porosity, one should either use zirconium salts as precursors or incorporate chelating agents in zirconium alkoxide solutions, both of which may effectively suppress the hydrolysis by ambient water vapor.

Titanium dioxide (TiO₂) thin films were deposited at 350 °C on thoroughly cleaned substrates using an economical spray pyrolysis process. The film’s structural, morphological, compositional, optical, and electrical properties were examined using XRD, Raman spectroscopy, XPS, FTIR, SEM, EDS, UV-Vis-NIR, and Hall-effect methods. The XRD analysis reveals the anatase nature of the film, with a reduction in peak intensities observed in the sample annealed at 450 °C. The EDX investigation reveals that the film is composed only of Ti and O, which has been confirmed by XPS analysis. FTIR studies confirmed the existence of Ti-O-Ti stretching bonds. The Raman spectra indicate the existence of microstress and anatase phases. SEM images suggest recrystallization during annealing may result in a slight rise in grain size within the crystalline films. The optical study reveals that air annealing is a useful technique to tailor a film’s porosity. The Hall effect study indicates the n-type material conductivity of films. Four distinct target gases-nitrogen dioxide (NO₂), carbon dioxide (CO₂), ammonia (NH₃), and hydrogen (H₂) were used to study the gas selectivity of the TiO₂ nanostructured-based metal oxide sensor at various operating temperatures. The sensor exhibits excellent stability, NO₂ gas selectivity, and response. The sensor’s optimum operating temperature was determined to be 250 °C and at this temperature, a response time of 53 s and a recovery time of 125 s were observed for a 5 ppm NO₂ gas concentration. The developed sensor may find use in medical and industrial fields.

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