Sol-gel Samples Research Articles

Synthesis of HTSP Y1<sub>1-x</sub>Fe<sub>x</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> by Sol-Gel and Solid-Phase Methods

A modified version of using of the sol-gel process at the initial stage of the synthesis of a high-temperature superconductor (HTSC) Y1-xFexBa2Cu3Oy with low Fe doping is proposed. The properties of samples obtained by sol-gel and solid-state synthesis have been compared. It has been shown that a more uniform distribution of the dopant throughout the volume of the sol-gel samples makes it possible to obtain materials with improved microstructural and performance characteristics.

Influence of synthesis methods on the structural, dielectric and magnetic properties of cobalt ferrites

A systematic study comprising structural, magnetic and dielectric properties of the cobalt ferrite (CoFe2O4) powders at first is carried out by way of synthesizing the materials using different preparatory methods, such as conventional solid-state method, wet chemical sol-gel autocombustion method using citric acid as well as glycine, separately as fuels. X-ray diffraction (XRD) studies reveal the formation of spinel phase with clear variations of peak intensities in all the samples. Morphology studies using scanning electron microscopy (SEM) reveal well grown grains in solid state synthesized sample compared to sol-gel autocombustion samples. The variations observed in the grain growth as well as densities (porosity) were attributed to typical temperature treatment conducted on the samples. Dielectric tests provide the evidence of space charge polarization in all the samples. Magnetic studies using vibrating sample magnetometry (VSM) provide the values of saturation magnetization and coercivity of the samples explored. The sol-gel autocombustion sample using glycine matrix (Cogly) shows higher saturation magnetization (Ms = 59.2 emu/gm) comparing to other samples whereas, sample with citric acid matrix results with lower Ms value as 36.5 emu/gm. The typical reasons for the observed variations in structural, microstructural, magnetic, dielectric and impedance properties of these materials were well addressed in terms of theoretical aspects and presented in this paper.

The photoluminescence studies of Gd3+/Tb3+ co-doped xerogels and nano-glass-ceramics dedicated for green-emitting devices

In this work, we reported the results of photoluminescent and structural investigations of Gd3+/Tb3+ co-doped silicate xerogels as well as derivative SiO2-LaF3 nano-glass-ceramics. The molar ratio of appropriate acetates used during the synthesis, i.e., La(AcO)3:Gd(AcO)3:Tb(AcO)3 was fixed to x:(0.95-x):0.05. Based on XRD measurements, the crystallization of hexagonal LaF3 nanophase was verified without any admixture of GdF3 phase, even for samples with La3+:Gd3+ molar ratio ≤1. The optical characterization of fabricated Gd3+/Tb3+ co-doped sol-gel materials involved the registration and analysis of photoluminescence excitation (PLE) and emission spectra (PL), as well as the decay curves for the 6P7/2 (Gd3+) and the 5D4 (Tb3+) excited levels. Upon excitation at λex = 275 nm wavelength, the fabricated sol-gel samples revealed the series of emission lines assigned to the electronic transitions from both dopants, i.e., Gd3+ and Tb3+, indicating apparently the occurrence of Gd3+/Tb3+ energy transfer process (ET). The photoluminescence measurements comprehensibly proved the competitiveness between Gd3+ and Tb3+ ions to be entered into LaF3 fluoride nanocrystal lattice, formed during annealing of as-prepared xerogels. Based on the recorded PL spectra for fabricated sol-gel samples, some chromatic parameters were calculated, i.e., chromaticity coordinates (CIE), correlated color temperatures (CCT), and color purities (CP). The prepared Gd3+,Tb3+ co-doped samples are able to emit green light with CCT values in a range from 5967 K to 6291 K, and high CP reached 70 %, which predispose them for use as efficient constituents for developing green-emitting devices.

Structural, morphological, optical, and magnetic properties of NiO-added NiCo2O4 electrode materials synthesized by sol-gel, Co-precipitation and ultrasonication methods and their electrochemical supercapacitor response

In this study, NiO-added NiCo2O4 composite samples were prepared using three distinct synthesis methods to study the impact of synthesis technique and NiO addition on the electrochemical performance of NiCo2O4. The chosen methods, sol-gel, co-precipitation, and ultrasonication, represent a range of approaches that yield different particle structures and morphologies. The structural and morphological studies of composite samples were investigated using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. XRD analysis revealed the crystalline composition, revealing the presence of two distinct phases: NiO and NiCo2O4. The Rietveld analysis of the composite samples supports the dual phases in the samples. FESEM analysis confirms the change in size and shape of the particles with the synthesis procedure. Optical properties, measured via UV–visible absorbance spectra, demonstrated that the energy gap varied with the synthesis method. The sol-gel samples exhibited the highest energy gap at 2.20 eV. The magnetic properties were measured using the vibration sample magnetometer (VSM), and the results confirm that the synthesis procedure influences magnetic loops and coercivity. The electrochemical performance of the samples in a 3 M potassium hydroxide electrolyte revealed that the co-precipitation method produced the highest capacitance of 398 Fg-1 at a 10 mV/s sweep rate, indicating superior energy storage capacity compared to pure NiCo2O4. Adding NiO phase to the NiCo2O4 matrix is believed to enhance electrochemical performance by creating additional charge at the grain boundaries, leading to a synergistic effect and improved electron and ion transport. The exceptional electrochemical performance of these composite materials suggests that the synthesis methods and the addition of NiO play a critical role in determining the overall efficiency and applicability of battery-type supercapacitors. These findings pave the way for further research into optimizing synthesis parameters to enhance energy storage capacity and inspire the development of advanced spinel metal oxide composite electrodes for supercapacitors and other energy storage applications.

CHARACTERIZATION OF A NOVEL ANTIMICROBIAL SOL-GEL DEVICE COATING TO PREVENT PERIPROSTHETIC JOINT INFECTION

An increasing elderly population means joint replacement surgery numbers are projected to increase, with associated complications such as periprosthetic joint infections (PJI) also rising. PJI are particularly challenging due to antimicrobial resistant biofilm development on implant surfaces and surrounding tissues, with treatment typically involving invasive surgeries and systemic antibiotic delivery. Consequently, functionalisation of implant surfaces to prevent biofilm formation is a major research focus. This study characterises clinically relevant antimicrobials including gentamicin, clindamycin, daptomycin, vancomycin and caspofungin within a silica-based, biodegradable sol-gel coating for prosthetic devices.Antimicrobial activity of the coatings against clinically relevant microorganisms was assessed via disc diffusion assays, broth microdilution culture methods and the MBEC assay used to determine anti-biofilm activity. Human and bovine cells were cultured in presence of antimicrobial sol-gel to determine cytotoxicity using Alamar blue and antibiotic release was measured by LC-MS. Biodegradability in physiological conditions was assayed by FT-IR, ICP-MS and measuring mass change. Effect of degradation products on osteogenesis were studied by culturing mesenchymal stem cells in the presence of media in which sol-gel samples had been immersed.Antimicrobial-loaded coatings showed strong activity against a wide range of clinically relevant bacterial and fungal pathogens with no loss of activity from antibiotic alone. The sol-gel coating demonstrated controlled release of antimicrobials and initial sol-gel coatings showed no loss of viability on MSCs with gentamicin containing coatings. Current work is underway investigating cytotoxicity of sol-gel compositions against MG-63 cells and primary osteoblasts.This research forms part of an extended study into a promising antimicrobial delivery strategy to prevent PJI. The implant coating has potential to advance PJI infection prevention, reducing future burden upon healthcare costs and patient wellbeing.

Effects of Synthesis Methods on the Characteristics of Material Sr3Y1.95Ge3O12: 0.05Eu3+ (SYGO: Eu3+) for White LED Phosphors Applications

Solid-state reaction, co-precipitation, and sol-gel procedures were used to synthesize the Sr3Y1.95Ge3O12:0.05Eu3+ (SYGO: Eu3+) garnet structure. The morphological structure and photoluminescence properties of the samples were studied. Phosphors have morphologies and particle sizes that vary depending on the preparation. According to the X-ray diffraction pattern measurement, the sol-gel sample only appeared to exhibit the SYGO: Eu3+ characteristic that it shows the cubic structure belonging to the Ia3d (230) space group. In comparison to the two approaches of co-precipitation and solid-phase reaction, the sol-gel method has a more single-phase structure. Under the excitation wavelength of 395 nm, all produced samples emitted red light, with the greatest emission peak at 612 nm, corresponding to the 5D0→7F2 transition of Eu3+ ions in the SYGO host lattice. The color coordinates of the sample SYGO: Eu3+ fabricated by the sol-gel method are x = 0.65 and y = 0.35. Therefore, the SYGO: Eu3+ based on sol-gel method’s synthesis is a promising phosphor for the application of White LED.

Studies of energy transfer process between Gd3+ and Eu3+ ions in oxyfluoride sol-gel materials

In this work, the series of silicate xerogels co-doped with Gd3+ and Eu3+ ions have been synthesized via a sol-gel method and further processed into nano-glass-ceramic materials. The mutual molar ratio of trivalent metal ions' acetates in samples’ compositions was gradually modified as follows: La3+:Gd3+:Eu3+ = (0.95-x):x:0.05, x = 0.05, 0.25, 0.45, 0.65, and 0.90; hence the molar ratio of Gd3+:Eu3+ (RGd/Eu) was set from 1 through 5, 9, 13 up to 18. XRD measurements confirmed the amorphous nature of fabricated xerogels, but their heat-treatment successfully triggered the crystallization of hexagonal LaF3 fraction with an average size of about ∼10 nm, which was additionally confirmed by HR-TEM microscopy. Additionally, it was found that the LaF3 phase crystallized in a whole range of proposed La(CH3COO)3:Gd(CH3COO)3 molar ratio, and Gd3+ ions played only the role of dopant and replaced La3+ cation in the fluoride crystal lattice. The optical characterization of prepared sol-gel samples involved the registration of absorption, excitation and emission spectra, along with the luminescence decay analysis from the 6P7/2 (Gd3+) and the 5D0 (Eu3+) excited states. For nano-glass-ceramics defined by RGd/Eu = 13 and 18, the unexpected prolongation of the τ(6P7/2):Gd3+ lifetimes was denoted, compared with samples singly-doped with Gd3+. The changes in photoluminescence behavior of studied samples are strongly dependent on the nature of the fabricated sol-gel samples, the established molar ratios of La3+:Gd3+:Eu3+, and the tendency of cation-exchange in LaF3 nanocrystal lattice by Gd3+ and Eu3+ ions.

Synthesis Routes on Electrochemical Behavior of Co-Free Layered LiNi0.5Mn0.5O2 Cathode for Li-Ion Batteries

Co-free layered LiNi0.5Mn0.5O2 has received considerable attention due to high theoretical capacity (280 mAh g-1) and low cost comparable than LiCoO2. The ability of nickel to be oxidized (Ni2+/Ni3+/Ni4+) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn4+ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi0.5Mn0.5O2 with good electrochemical performance. In this study, Layered LiNi0.5Mn0.5O2 has been synthesized by sol-gel and solid-state routes. According to the XRD, the sol-gel method provides a pure phase, and solid-state process only minimize the secondary phases to certain limit. The Ni2+/Mn4+ content in the sol-gel process was higher than in the solid-state reaction, which may be due to the chemical composition homogeneity of the sol-gel samples. Regarding the electrochemical behavior, sol-gel process is better than solid-state reaction. The discharge capacity is 145 mAh/g and 91 mAh/g for the sol-gel process and solid-state reaction samples, respectively.

Self-diffusion in polycrystalline Li1+x Ti2-x Al x (PO4)3 (0.2 ≤ x ≤ 0.4) samples followed by 7Li PFG (pulse field gradient) NMR spectroscopy.

Short and long range lithium motions in powder Li1+x Ti2-x Al x (PO4)3 (LTAP) NASICON compounds prepared by ceramic (x = 0.2 and 0.4) and sol-gel (x = 0.3 and 0.4) routes are discussed. ND diffraction and MAS-NMR spectroscopy were previously used to investigate structural features of these compounds. In particular, Fourier map differences showed that the amount of Li atoms allocated at M3 increases at the expense of M1 sites when the Li content increases. In this work, PFG-NMR results show that diffusion coefficients rise with the amount of lithium and temperature. The restricted diffusion inside NASICON particles is compared with "free" diffusion processes. At 300 K, diffusion coefficients D PFG ∼ 5 × 10-12 m2 s-1 have been deduced in ceramic x = 0.2 and 0.4 samples, decreasing with diffusion time Δ used in PFG experiments. In sol-gel samples, diffusion coefficients are near those of ceramic samples, but decrease faster with diffusion Δ times, as a consequence of the Li confinement inside sub-micrometric crystallites. The NMR spin-echo signal displays minima at specific q(γgδ) values that are related to the crystallite size. From R dif ∼ q m -1 distances, calculated from the position of minima, and from diffusion coefficients deduced for high Δ values, the mean crystallite size was estimated. Finally, from the temperature dependence of conductivity and diffusion coefficients, the activation energy and charge carriers concentrations were determined.

Development and performance of CeO2 supported BaCoO3−δ perovskite for chemical looping steam methane reforming

Chemical looping steam methane reforming (CL-SMR) is a promising approach to co-production of syngas and hydrogen, and the reactivity of oxygen carriers is crucial in the performance of CL-SMR. In this study, CeO2 supported BaCoO3-δ oxygen carriers with different component distributions (labeled as dry-mix, sol-gel, co-sol-gel samples) were prepared and evaluated in CL-SMR. The BaCoO3-δ was loosely attached on CeO2 in the dry-mix sample, resulting in a high resistance to oxygen mobility and a low gas production. The co-sol-gel sample possessed impurities of Co3O4, BaCO3 and BaCeO3, which decreased reaction capacity and enhanced the secondary reaction of methane decomposition, leading to an excessive H2/CO ratio of syngas and coke formation. The contact of perovskite and CeO2 in sol-gel sample favors the synergistic effect of perovskite and CeO2, where the H2/CO ratio was close to the ideal value of 2 at 850 °C with the produced syngas and hydrogen reaching 4.57 mol/kg and 1.47 mol/kg, respectively. In situ Diffuse Reflectance Infrared Fourier Transform spectroscopy was employed to investigate the reaction mechanism of partial oxidation of methane, indicating that CH4 is gradually dehydrogenated and partially oxidized by lattice oxygen, and the conversion of -O-CH3 into -CHO and H2 is the rate-controlling step.

Effect of the fabrication process on the superconducting properties of Pb-BSCCO

Bismuth based high Tc superconductors are among the materials that have been extensively appreciated in terms of their application. Since this type of superconductors are very sensitive with respect to synthesis process, here, we consider effect of synthesis process on the electrical, magnetic and superconducting properties of Pb-BSCCO compound. The samples were prepared by both solid state and sol-gel reaction. In both of the preparation routes, two different methods of Cold Press (CP) and Spark Plasma Sintering (SPS) were used to compress the samples after, the completion of their calcination and grinding. In the next step, the samples put through the thermal process of sintering with different temperatures with respect to their preparation method. The results of the measurements indicate better superconducting properties in sol-gel method compare to the solid-state method. Also, it indicates better superconducting properties in Cold Press samples with respect to the samples prepared by SPS method. To compare the sintering temperature indicates that 825 and 830 oC are suitable temperature for sol-gel and solid-state samples, respectively, in Cold Press process.

Comparative analysis on the thermal, structural, and electrochemical properties of Al-doped Li7La3Zr2O12 solid electrolytes through solid state and sol-gel routes

Over the last decade, Li7La3Zr2O12 (LLZO) has shown to be one of the most promising materials as a solid electrolyte in Li-ion batteries. However, several factors can affect the final electrochemical properties of the material, such as the synthesis method and the inclusion of dopants. In this study, we conduct a comparative analysis of undoped and Al-doped LLZO prepared through solid state and sol-gel methods. An in-situ thermal investigation on the synthesis of LLZO shows how solid state synthesis forms LLZO at lower rates, however the resulting LLZO is more stable at higher temperatures. The addition of Al as a dopant further increases the thermal stability of the material by lowering its decomposition rate. Ionic conductivity measurements reveal how sol-gel LLZO samples experience several times higher conductivity than their solid state counterparts due to tightly interconnected grains. With the addition of Al, the conductivity further increases by two orders of magnitude. With that we are able to achieve the highest ionic conductivity of 4.96 × 10−4 S/cm for Al-doped sol-gel LLZO and an activation energy of 0.28(1) eV. This work provides a better understanding of how different synthesis methods affect the final properties of LLZO solid electrolytes.

Significantly enhanced UV-light-driven photocatalytic performance of ferroelectric (K0.5Na0.5)NbO3: Effect of corona-poling and particle size

This work focuses on the effect of corona-poling and particle size on photocatalytic performance of (K0.5Na0.5)NbO3 (KNN) ferroelectric powder synthesized by solid-state reaction (sample abbreviated as “KNN-cera”) and sol-gel (sample abbreviated as “KNN-nano”) techniques. Results show that degradation efficiencies of RhB solution under UV light irradiation with ferroelectric KNN-cera (average particle size: 1.21 μm) and KNN-nano (average particle size: 0.197 μm) poled under 1.5 kV/mm field were 89.5% and 96.5% whereas for unpoled KNN-cera and KNN-nano samples it was 29.4% and 86.09% respectively. The KNN-nano sample has shown better photocatalytic activity due to smaller size of the calcined powder. Corona poling treatment given to the synthesized powder displays a great influence on the photocatalytic activity due to enhancement in internal polarization field that makes photogenerated free electrons and holes move in the opposite directions, resulting in the spatial separation of free electrons and holes providing them with more time to participate in surface reactions. This helps in achieving better photocatalytic performance.

Correlating the effect of preparation methods on the structural and magnetic properties, and reducibility of CuFe2O4 catalysts.

CuFe2O4 spinel oxide has attracted research interest because of its versatile practical applications, especially for catalysis. In this study, nanometre-sized CuFe2O4 particles were prepared by three different methods, including nanospace confinement in SBA-15, hard template removal, and sol–gel combustion. The relationship between structure, size, magnetic behaviour, and reducibility of the catalysts was further investigated by various advanced techniques. Samples prepared by impregnation and hard template removal show high surface area and small crystallite size with superparamagnetic behaviour. In contrast, the sol–gel sample exhibits ferromagnetic properties with a large crystallite size and low surface area. Although all samples present a tetragonal crystal structure, the distributions of Fe and Cu cations in tetrahedral and octahedral sites in the spinel structure are different. The reducibility results demonstrate that the supported CuFe2O4/SBA-15 shows the lowest reduction profile. These results could suggest that the synthesis method strongly affects the crystal properties and cation distribution in the spinel structure, microstructure, surface area and reducibility, which are among the most relevant physicochemical properties for the catalytic activity.

Comparative study of Tl-1223 superconductors prepared by the sol-gel route and solid-state reaction

This paper presents sol-gel (SG) and solid-state reaction (SSR) pathways to produce multiphase ceramic precursors of BCCO and then the superconducting phase of Tl-1223. The heat treatments showed that to obtain high-purity precursors prepared by SG and SSR methods are sufficient to heat treatments at 915 and 945 °C, respectively. Furthermore, the diamagnetic onset temperature of the superconducting transition for the Tl-1223 samples prepared by precursors SG at 915 °C and SSR at 945 °C is approximately 120 K, and complete screening of applied ac magnetic fields observed at T ≈ 102 and ≈ 94 K, respectively. In addition, the value of the transport critical current density Jc for SSR was 128 A/cm2, whereas for the SG sample it was precisely 174 A/cm2. Thus, we could conclude that using wet chemistry offers some advantages over classical solid-state ceramic processing, significantly better chemical homogeneity, and higher reactivity of the precursor powder.

Impact of the Synthesis Method on the Conventional and Persistent Luminescence in Gd3-xCexGa3Al2O12.

The series of Gd3–xCexGa3Al2O12 nanopowders doped with different concentrations of Ce3+ ions were prepared by Pechini (sol–gel) and combustion methods. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. It was found that the synthesis method has a great impact on the morphology and, consequently, spectroscopic properties of the powders. Optical properties of the powders were examined using excitation, emission, and luminescence kinetic measurements. For all powders, persistent luminescence and emission decay processes were studied. The most intense luminescence was observed for the powder with 0.5 mol % of Ce3+ synthesized using the combustion method and 1 mol % in the case of the sol–gel sample. The longest and brightest persistent luminescence was observed for the powders doped with 0.1 mol % (combustion) and 0.2 mol % of Ce3+ ions (sol–gel). The thermoluminescence measurements were done for the powders prepared using different methods to understand the impact of the synthesis conditions on the number and depths of the traps involved in persistent luminescence. On the basis of spectroscopic measurements, the mechanism of persistent luminescence was constructed and discussed.

Radioluminescence Response of Ce-, Cu-, and Gd-Doped Silica Glasses for Dosimetry of Pulsed Electron Beams.

Radiation-induced emission of doped sol-gel silica glass samples was investigated under a pulsed 20-MeV electron beam. The studied samples were drawn rods doped with cerium, copper, or gadolinium ions, which were connected to multimode pure-silica core fibers to transport the induced luminescence from the irradiation area to a signal readout system. The luminescence pulses in the samples induced by the electron bunches were studied as a function of deposited dose per electron bunch. All the investigated samples were found to have a linear response in terms of luminescence as a function of electron bunch sizes between Gy/bunch and Gy/bunch. The presented results show that these types of doped silica rods can be used for monitoring a pulsed electron beam, as well as to evaluate the dose deposited by the individual electron bunches. The electron accelerator used in the experiment was a medical type used for radiation therapy treatments, and these silica rod samples show high potential for dosimetry in radiotherapy contexts.

A comparative study on high TCR and MR of La0·67Ca0·33MnO3 polycrystalline ceramics prepared by solid-state and sol-gel methods

In this work, La0·67Ca0·33MnO3 (LCMO) polycrystalline ceramics were fabricated by solid-state (SS) and sol-gel (SG) methods. Morphologies, crystal structures, element compositions, and contents of as-obtained LCMO ceramics were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and X-ray photoemission spectroscopy (XPS). Compared to the SG ceramic, specimens fabricated by SS showed numerous smaller grain size particles and scattered grain boundaries (GBs), leading to higher resistivity. Values of the peak temperature coefficient of resistivity (TCR) of both LCMO ceramics prepared by SS and SG were recorded as 14.12% at 261.73 K and 31.96% at 260.64 K, respectively. Respective magnetic resistance (MR) values were estimated to 29.97% at 264.78 K and 54.27% at 263.80 K, respectively. Also, SG sample displayed LCMO polycrystalline with better crystal quality, as well as improved electrical and magnetic properties. Hence, SG method was more suitable for preparation and application of LCMO ceramics, especially for use in highly sensitive infrared detectors and magnetic sensors.

Effects of Material Preparation in Polyimide/SiO2 Nanocomposites for Low-Temperature Dielectric Applications

Introducing nanomaterial fillers into a host polymer can significantly change its properties and affect its behaviors. The resulting nanocomposites have the potential to possess new, often enhanced characteristics, making them uniquely qualified for a broader spectrum of new applications. This research investigates the effects of material preparation on nanocomposites using polyimide (PI) as the host polymer and silicon dioxide (SiO2) nanoparticles as the filler. The fabrication and characterization of the PI/SiO2 nanocomposites were explored based on samples produced from two different approaches—a direct mixing process using as-purchased SiO2 nanoparticles and a sol-gel process that relied on chemical reactions to produce SiO2 inside a solvent. The prepared samples and the distribution of the SiO2 nanoparticles in the nanocomposites were characterized with profilometry and scanning electron microscopy (SEM). The characterization showed that the directly mixed samples contained visible nanoparticle agglomerates while the sol-gel films had the nanoparticles uniformly distributed inside the host polymer. The DC dielectric breakdown testing revealed that the sol-gel films outperformed the directly mixed samples at both room (300 K) and cryogenic (164 K) temperatures. When the temperature is cooled down to 92 K, the sol-gel samples demonstrated higher dielectric strengths than pure PI films. Our investigation shows that high-quality PI/SiO2 nanocomposites, especially when prepared through the sol-gel process, are promising candidates as dielectrics that can be used in a variety of cryogenic applications.

Comparative Study of the Physical Properties of Fine-Crystalline Mechanoactivated and Sol–Gel Samples of YBa2Cu3O6.92 High-Temperature Superconductors

A technique based on the sol–gel technology is developed for the synthesis of fine-crystalline YBa2Cu3O6.92 (Tc = 91.5 K) high-temperature superconductors (HTSCs), including the step-by-step annealing of the samples in tablet form at the annealing temperature Tann = 750°C in an argon atmosphere. Having the same microstructure with the average crystallite size $$\left\langle D \right\rangle $$ = 200 nm, the sol–gel samples exhibit different magnetic and thermodynamic properties, depending on the number of anneals in argon. Comparison of the characteristics for sol–gel and mechanoactivated fine-crystalline samples of the same composition made it possible to make an assumption about the implementation of incomplete atomic ordering in sol–gel samples at the first stage of annealing with an increase in the degree of structural ordering during the next two stages. This may be the main reason for the change in the physical characteristics of the HTSC sol–gel samples structured at the nanoscale level, depending on the number of annealings in an argon atmosphere.