Different types of materials in the TiO2-SiO2 system are widely applied in many branches of industry and science because of their valuable properties, which makes them a continuous subject of structural research. Therefore, a comparison of the structure and microstructure of TiO2-SiO2 thin films deposited using two significantly different methods, the sol–gel method and PVD with an oxygen plasma source (PE-PVD), became the main aim of this work. For particular applications, coatings obtained via the sol–gel method may exhibit selected properties comparable to those of coatings synthesized using the more demanding and expensive PE-PVD method. Additionally, bulk samples of titania and silica gels were synthesized and annealed at 500 °C, 1000 °C and 1200 °C as reference materials. XRD, GID, FTIR and Raman spectroscopy were applied as structural characterization methods. SEM and AFM were also used to investigate the surface morphology of the samples. Additional QNM AFM measurements allowed the adhesion of the samples to be determined. The hydrophilicity/hydrophobicity of the thin films was assessed using a Krüss DSA25E goniometer and ADVANCE software (version 1.11, Krüss Scientific, Hamburg, Germany), XRD, GID and FTIR measurements enabled the identification of anatase and rutile phases in the annealed gels and deposited coatings. The particle sizes were similar for all coatings, regardless of the deposition method or substrate type. Thermal cracks in the thin film obtained by dip coating strongly influenced its hydrophilicity, in contrast to the coatings obtained by PE-PVD, which exhibited hydrophobic behavior.
Low-temperature heat treatment in magmatic sapphires can be difficult to detect because conventional indicators, including hydroxyl-related absorptions and short-wave ultraviolet fluorescence, are often weak, absent, or inconclusive in Fe-rich material. This study evaluates Fourier transform infrared (FTIR) reflectance spectroscopy as a method for detecting low-temperature heat treatment in Vietnamese magmatic sapphires. A total of 38 natural sapphires from basalt-related deposits in southern Vietnam, comprising 23 samples from Dak Lak and 15 samples from Phan Thiet, were analyzed before and after heating at 1100 °C for 3 h under oxidizing conditions. Particular attention was given to spectral modifications within the fingerprint region (1000–500 cm−1), which is dominated by lattice-vibrational modes of α-Al2O3. Following heat treatment, all samples exhibited a systematic shift in the dominant reflectance trough-center position from 646.4 ± 2.0 cm−1 to 630.2 ± 0.8 cm−1 together with a substantial increase in trough depth from 0.052 ± 0.025 to 0.705 ± 0.118%R (p < 0.0001). The spectral feature also became narrower and more sharply defined after heating, consistent with modification of the local vibrational environment within the corundum lattice. In contrast, hydroxyl-related absorptions in the 3100–3700 cm−1 region were weak, variably developed, or absent and showed no reproducible treatment-related behavior. Complete separation between untreated and heat-treated samples was achieved when trough-center position and trough depth were evaluated jointly. These results demonstrate that FTIR fingerprint-region parameters derived from intrinsic α-Al2O3 lattice vibrations provide robust indicators of low-temperature heat treatment in Vietnamese magmatic sapphires and may serve as complementary criteria when conventional OH-based indicators are inconclusive.
Fourier-based analysis of strain and rotation in differently oriented crystal domains in high-resolution electron microscopy lattice images requires consideration of the lattice signals and reciprocal bases associated with each domain. Here, the strain tensor using the computational Fourier transform moiré (STC) method was applied to a high-resolution transmission electron microscopy (HRTEM) image of a magnesium twin boundary by combining domain-specific reciprocal bases, amplitude-based pixel selection, far-field referencing, and real-space stitching. Uniform synthetic deformations verified the recovery of all four displacement-gradient components and their strain–rotation decomposition. Spatially varying deformations with added noise were used to evaluate sensitivity to filter radius and signal-amplitude threshold. With identical filtering and common evaluation pixels, STC and geometric phase analysis yielded similar results, including filter-induced attenuation of deformation peaks. In a two-domain synthetic image with a 36.87° orientation difference, applying the filter, carrier, and reconstruction basis of one domain to the other produced componentwise root-mean-square errors of approximately 23–50 percentage points. Basis mixing alone cannot explain these errors; carrier mismatch, changes in the transmitted signal, and low signal amplitudes also contribute. The experimental maps show relative projected strain and residual rotation referenced to the far field of each domain, with the boundary core excluded. Bragg-signal amplitudes support domain-specific signal assignment but do not independently validate strain accuracy, and quantitative interpretation remains limited in regions with weak signals.
Hydrogen blending in natural gas pipelines poses an embrittlement risk to girth welds. This study investigated an API X70 girth weld in CH4-H2 mixtures containing 5–20% H2 at 4–10 MPa using slow strain rate tensile testing, fractography, and electron backscatter diffraction (EBSD). Relative to pure CH4, the maximum reductions in yield and ultimate tensile strengths were 7.2% and 3.9%, respectively, whereas elongation decreased from 16.46% to 13.04% under the 10 MPa-20% H2 condition. Fractography revealed increasingly extensive edge-localized quasi-cleavage (QC) regions under higher hydrogen exposure conditions. Post-fracture EBSD revealed condition-dependent differences in micro-void morphology and secondary cracking. At 7 MPa-20% H2, intersecting high KAM bands in two regions near a representative secondary crack exhibited local peak values of 2.65°–3.87° and were geometrically compatible with distinct {110} plane traces. However, the examined crack path did not consistently follow a single {110} trace. These findings indicate a close association between QC cracking and localized intragranular plastic deformation and were consistent with a contribution from hydrogen-enhanced localized plasticity (HELP), although vacancy-mediated damage and hydrogen-enhanced decohesion could not be excluded.
Understanding the extent to which the supramolecular crystalline organisation of native wood is associated with its macroscopic, thermal and micromechanical properties remains an active area of inquiry in biomass characterisation. In this study, the crystalline, thermal, and micromechanical characteristics of Oriental spruce (Picea orientalis (L.) Peterm.), Scots elm (Ulmus glabra Huds.), Canadian poplar (Populus × canadensis Moench), Austrian pine (Pinus nigra J.F. Arnold), Turkish red pine (Pinus brutia Ten.), and black locust (Robinia pseudoacacia L.) were comparatively investigated using X-ray diffraction (XRD), thermogravimetric–derivative thermogravimetric (TGA-DTG) analysis, Vickers microhardness, and density measurements. Microhardness generally aligned with density trends among the sampled wood specimens; black locust exhibited the highest density (0.727 g/cm3) and, alongside Austrian pine, recorded the highest mean parallel-to-grain hardness (18.0 kgf/mm2). In the perpendicular-to-grain direction, Turkish red pine reached the maximum value (9.9 kgf/mm2). Conversely, Canadian poplar yielded the lowest values across all three evaluated parameters (0.371 g/cm3 density, 6.7 kgf/mm2 parallel, and 3.1 kgf/mm2 perpendicular). XRD profiles confirmed the characteristic cellulose I structure in all examined specimens, with the (200) reflection occurring at 22.06–22.31° and crystallinity index (CrI) values ranging from 55.91% (Scots elm) to 60.07% (Turkish red pine). Apparent crystallite sizes (L200) ranged from 2.68 nm (Scots elm) to 2.94 nm (black locust), indicating modest variation in the measured crystalline parameters. TGA-DTG analysis revealed variation in the observed thermal degradation profiles, with maximum degradation temperatures of 333.0–366.7 °C and total mass losses of 52.3–65.3%. Exploratory comparisons indicated that these nanoscale crystallographic parameters do not present a simple linear relationship with macroscopic thermal mass loss or hardness. Overall, these findings indicate that cellulose crystalline organisation, thermal degradation, density, and micromechanical behaviour are interconnected yet non-equivalent properties. Integrating these multiparametric evaluations provides further insight into the relationships between nanoscale cellulose organisation and the higher-level properties of wood.
