Increasing SiO2 Content Research Articles

Optimization of Hydrogen Utilization and Process Efficiency in the Direct Reduction of Iron Oxide Pellets: A Comprehensive Analysis of Processing Parameters and Pellet Composition

The article deals with the H2 consumption for different processing conditions and the composition of the processed pellets during the direct reduction process. The experiments are carried out at 600–1300 °C, with gas pressures of 1–5 bar, gas flow rates of 1–5 L min−1, and basicity indices of 0 to 2.15. Pellets with different compositions of TiO2, Al2O3, CaO, and SiO2 are analyzed. The gas flow rate is crucial, with 0–10 L min−1 leading to an H2 consumption of 0–5.1 kg H2/kg pellet. The gas pressure (0–10 bar) increases the H2 consumption from 0 to 5.1 kg H2/kg pellet. Higher temperatures (600–1300 °C) reduce H2 consumption from 5.1 to 0 kg H2/kg pellet, most efficiently at 950–1050 °C, where it decreases from 0.22 to 0.10 kg H2/kg pellet. An increase in TiO2 content from 0% to 0.92% lowers H2 consumption from 0.22 to 0.10 kg H2/kg pellet, while a higher Fe content (61–67.5%) also reduces it. An increase in SiO2 content from 0% to 3% increases H2 consumption from 0 to 5.1 kg H2/kg pellet. Porosity structure influences H2 consumption, with the average pore size decreasing from 2.83 to 0.436 mm with increasing TiO2 content, suggesting that micropores increase H2 consumption and macropores decrease it.

Tunable Magnetic and Dielectric Properties of BaMg0.4Al0.4Fe11.2O19 and SiO2 Composites for High-Frequency Applications

This study focuses on the synthesis and characterization of Mg and Al co-doped M-type Barium hexaferrite (BaMg0.4Al0.4Fe11.2O19) powder via the sol-gel method. Structural analysis using X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) confirmed the single-phase structure of the synthesized powder. Morphological properties were examined through field emission scanning electron microscopy (FESEM), revealing hexagonal particle morphology with an average size of approximately 60 nm for BaMg0.4Al0.4Fe11.2O19. To fabricate composites, commercially purchased SiO2 was used to prepare the composites of (1–x) BaMg0.4Al0.4Fe11.2O19+ (x) SiO2 {where x = 0.0, 0.1, 0.3, 0.5 and 0.7). The composites were prepared using the mixing method followed by microwave sintered at 1000 °C/90 min. FESEM and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the morphology and elemental composition of the composites. The composites ‘ frequency-dependent complex permittivity was measured over 300 kHz to 3 GHz. Magnetic hysteresis (M-H) loops were used to analyze the magnetic properties of composite samples. A reduction in magnetic saturation was observed with increasing SiO2 concentration, while there was a slight increase in coercivity for the composite samples compared to pure hexaferrite. Coercivity remained relatively unchanged with varying SiO2 concentrations in the composites. A possible relation between the magnetic and dielectric properties and the microstructure of the sintered composites with the composition variation was investigated.

Structural evolution study by solid-state NMR of photopolymerizable aluminophosphosilicate hybrid materials

Aluminophosphosilicate materials of composition (mol.%) xSiO2[(Al2O3)50–(P2O5)50]100-x were prepared through sol-gel method and heat-treated yielding non-crystalline materials. The structural evolution from the hybrid to heat-treated material as a function of the SiO2 content was studied by 13C, 29Si, 31P and 27Al solid-state NMR, infrared spectroscopies, X-ray diffraction and differential scanning calorimetry (DSC). NMR analyses showed the AlPO4 formation in the matrix and heterocondensation, forming Al-O-P and P-O-Si linkages. The heat treatment promoted the formation of a more interconnected SiO2 tetrahedra network as the SiO2 content increased. Similar to the hybrid materials, the increase of SiO2 content induces the replacement of P-O-Al(IV) bonds by Si-O-Al(IV) bonds in the heat-treated materials as confirmed by 27Al NMR and 27Al{31P} REDOR data, which was also supported by Raman analysis. This sol-gel route provides a novel way to fabricate new homogeneous materials, which can be doped with rare earths and applied to new optical devices.

Effect of SiO2 content in magnesia flux pellets on softening-melting and dripping behavior of comprehensive burden structure

High-proportion pellet smelting is the current development direction of blast furnace burden structures in China. And that is an inevitable trend for the future steel industry to achieve pollution reduction and carbon reduction. This study focuses on the mixed burden of magnesia flux pellets with different SiO2 contents, sinter, and lump ore. The influence of SiO2 content on the softening-melting behavior of comprehensive burden and the high-temperature interaction between magnesia flux pellets and sinter were studied through droplet experiments and visual experiments. The results show that with increasing SiO2 content, the T10 of magnesia flux pellets gradually decreases, while the T10 of the comprehensive burden shows no significant change. The TS of both shows a gradually decreasing trend with increasing SiO2 content. However, due to the good matching of the melting range between sinter and magnesia flux pellets in the comprehensive burden, the trend of TS change in the comprehensive burden is relatively slow. The air permeability of the comprehensive burden has significantly improved compared with the single magnesia flux pellets; The interaction between magnesia flux pellets and sinter occurs through the liquid phase. The fayalite phase in the pellets reacts with the main high melting point substance Ca2SiO4 in the sinter to generate a new low melting point kirschsteinite. With the increase of SiO2 content, the content of kirschsteinite in the comprehensive burden increases. That is also the reason for the decrease in TS of the high silicon comprehensive burden; With the increase of SiO2 content, the maximum pressure difference and characteristic values of magnesia flux pellets and comprehensive burden gradually increase. When the SiO2 content exceeds 6%, the maximum pressure difference and characteristic value of a single pellet sharply increase, while the trend of the maximum pressure difference and characteristic value change of comprehensive burden is relatively gentle. Its characteristic values are below 980 kPa·°C. At this time, the air permeability of the comprehensive burden is significantly improved compared to the single magnesia flux pellets. In the case of SiO2 content exceeding 6%, the addition of a sinter can effectively address the soft melting performance of high-silica magnesia flux pellets and enhance column air permeability. In addition, the high drop temperature of the high-silica comprehensive burden is due to the presence of a large amount of MgO in the magnesia wustite during the later stage of reduction, which increases the melting point. And the MgO content in the slag is relatively low. That causes a sharp increase in slag viscosity and makes it difficult to separate the slag from iron.

Effects of Ca<sup>2+</sup>/Mg<sup>2+</sup> ions in recycled water on the reverse flotation properties of iron oxides

Water quality, particularly hardness, plays an important role in affecting the floatability of minerals as it interferes with the chemical/electro-chemical characteristics of mineral surfaces and their interactions with flotation reagents. It could become unpredictable when water sources characterized by different calcium or magnesium ion distributions were involved. This study aimed to identify the role of Ca<sup>2+</sup>/Mg<sup>2+</sup> ions in the recycled water on the cationic reverse flotation selectivity of iron oxides through a series of bench/micro flotation tests, zeta potential, powder contact angle, and Fourier Transform Infrared (FTIR), etc. The results pointed out that the use of recycled tailing water deteriorates the flotation selectivity and dilutes the concentrates. This can be largely attributed to the presence of Ca<sup>2+</sup> ions at higher concentrations as they induce a drop in the Fe recovery and an increase in SiO2 content while an increase in the content of Mg<sup>2+</sup> ions seems to have little effect on the quality of concentrate. As evidenced by the data from micro-flotation, powder contact angle, zeta potentials, and FTIR, a hydrophilic colloidal layer formed by Ca-based hydrolyzed compounds, such as Ca(OH)<sup>+</sup> or, CaCO<sub>3(s)</sub>, etc., on quartz could change its zeta potentials and disturb its interactions with a cationic collector. They also play a role in weakening the flocculation of starch on hematite probably by pre-locking the acidic groups on the starch remnants and contracting their configurations, thus preventing their adsorption on mineral surfaces. However, magnesium ions seem to be beneficial to in strengthening the flocculation of starch on hematite as magnesium-based species could act as adsorption bridges of between starch and mineral surfaces.

An enhanced chemical maturation of juvenile arc crust recorded by the Urad Houqi intrusive suite in Langshan arc, Central Asia

Continental arc magmatism is crucial in producing juvenile continental crust of andesitic to dacitic composition, yet its impact on the formation of the modern mature continental crust, which is more enriched in potassic and granitic components, remains poorly understood. We examined a suite comprised of norite gabbro, gabbroic diorite, high-Mg diorite, dioritic enclave, and medium-K to high-K granites (the Urad Houqi suite) from the Langshan arc in the southern Central Asian Orogenic Belt (CAOB). Zircon U-Pb geochronology indicates that the Urad Houqi suite was formed ca. 278−268 Ma by a continuous magmatic event, marking the final episode of the late Paleozoic continental arc magmatism in the southern CAOB induced by the subduction of the Paleo-Asian Ocean. The suite exhibits a more potassic and fertile composition compared to typical continental arc magmas, and shows a continuous increasing K2O/Na2O ratio and incompatible element concentrations, including K, Rb, Th, and U, with increasing SiO2 content. The geochemical evolution of the suite offers valuable insights into the maturation process of the juvenile arc crust. By combining zircon Hf and bulk-rock Sr-Nd-Pb isotope studies, we demonstrated that the various lithologies within the Urad Houqi suite recorded a three-stage enhancement of the geochemical fertility of the juvenile Langshan arc crust: (1) generation of the initially fertile primary melt from the mantle wedge metasomatized by the recycled subducted sediments; (2) trans-crustal open-system hybridization processes, including peritectic reaction and magma mixing, that further fertilized the derived melts in addition to fractional crystallization; and (3) diverse petrogenetic processes that contributed to the fertility of the granitic magmas, including polybaric fractionation of the primary magma, anatexis of ancient crust, and extraction of high-silica melts from the shallow mush system. The three-stage maturation of the juvenile Langshan arc crust was typically coupled with the accelerated subduction of the Paleo-Asian Ocean since the earliest Permian. Our study finds that the Urad Houqi suite can serve as an example of modern continental crust maturation at continental arc settings.

Influence of SiO2–ZnO mixed soft abrasive on tribological behavior and polishing performance of sapphire wafer

The use of reactive soft abrasives, capable of undergoing solid-state reactions with sapphire, is a promising approach for low-damage and low-contamination machining of sapphire wafers. This study calculates the Gibbs free energy change of these chemical reactions based on thermodynamic principles. SiO2–ZnO mixed soft abrasives were selected for the polishing of sapphire wafers. Friction and wear experiments were conducted to explore the tribological behavior of sapphire wafers with various mixed abrasives, leading to the optimization of the abrasive composition. The results show that mixed abrasives significantly enhance the material removal rate (MRR) of sapphire wafers. As the proportion of SiO2 in the mixture increases, the MRR correspondingly rises. Specifically, an SiO2–to–ZnO ratio of 2:1 in the mixed abrasives results in a 91.68% increase in MRR compared to using SiO2 abrasives alone. Based on these findings, five grinding discs with different abrasive ratios were prepared using a resin binder for mechanical–chemical polishing experiments on sapphire wafers. The polishing results corroborate those of the friction and wear experiments, confirming that an increased SiO2 content in the mixed abrasive discs leads to higher MRR. With a 2:1 ratio of SiO2 to ZnO in the mixed abrasive disc, the MRR is enhanced by 342.9% compared to discs with only SiO2 abrasives, while reducing the surface roughness to 3.21 nm. In the SiO2–ZnO mixed abrasives, the inclusion of ZnO enhances chemical reactions during polishing. Aided by the mechanical removal efficacy of SiO2, this approach significantly increases MRR while maintaining superior polishing quality.

Optimization of spraying process and stoichiometric stage of plasma‐sprayed Yb2Si2O7 environmental barrier coating

AbstractYtterbium disilicate (Yb2Si2O7) is a potential environmental barrier coating (EBC) material. In this paper, the microstructure and phase composition of plasma‐sprayed Yb2Si2O7 coatings with different spraying process were systematically investigated to optimize the spraying power and spraying distance. Furthermore, in order to obtain Yb2Si2O7 coating with single phase, a certain proportion of SiO2 was added to the Yb2Si2O7 powder to compensate for the volatilization of SiO2 during plasma‐spraying process, and the influence of spraying powder composition on the microstructure and phase structure (composition and content) of Yb2Si2O7 coatings were also characterized in detail. The results showed that the Yb2Si2O7 coating was dense with fewer pores and cracks at the spraying power of 40 kW and the spraying distance of 100 mm. Yb2Si2O7 coating with the “sandwich” structure was composed of Yb2Si2O7, Yb2Si2O7 + Yb2SiO5, and Yb2SiO5 three microstructures, which was mainly caused by the volatilization of SiO2 in Yb2Si2O7 spraying powder. The Yb2Si2O7 coating contained 90.68 mol.% Yb2Si2O7 phase and 9.32 mol.% Yb2SiO5 phase after crystallization at 1300°C for 20 h. The coating was composed of Yb2Si2O7 phase and amorphous phase after SiO2 addition. Yb2SiO5 phase precipitated from the coating after heat treatment at 1300°C, and its content decreased with the increase of SiO2 content. The content of the Yb2Si2O7 phase was as high as 99.41 mol.% when SiO2 content was 10 mol.%, which would provide a scientific basis for further research on stoichiometric Yb2Si2O7 EBCs with excellent properties.

Study on the Effect of SiO2 Content on the Properties of Epoxy Resin

With the development of energy layout in western China, the construction and operation of hydro-generator units in high-altitude and cold regions such as Tibet and Qinghai have increased rapidly, which puts forward stricter requirements for the insulation and anti-corona technology of high-altitude units. Improving the intrinsic properties of the matrix material is a highly efficient anti-corona method. In the paper, epoxy resin composites doped with different contents of micron silica were prepared. The effects of 0.5 wt%, 1 wt%, and 1.5 wt% SiO2 on the thermal conductivity, dielectric properties, and breakdown field strength of the matrix resin were researched. The results in this paper show that the doping of different contents of SiO2 has little effect on the thermal conductivity of the matrix resin, but improves the dielectric properties of the matrix resin to a certain extent. With the increase of SiO2 content, the breakdown field strength of the composites increased primarily and then decreased.

Enhanced Mechanical Properties of PUMA/SiO2 Ceramic Composites via Digital Light Processing.

This study aims to enhance the mechanical properties of additively manufactured polymer parts by incorporating ceramic particles (SiO2) into diluted urethane methacrylate (UDMA) photopolymer resin using digital light processing (DLP) technology. The resulting PUMA/SiO2 composites, featuring varying SiO2 contents (16.7, 28.5, and 37.5 wt%) and processed under different conditions, underwent a comprehensive series of mechanical, thermal, and chemical tests. Hardness tests showed that composites with 37.5 wt% SiO2 demonstrated superior hardness with low sensitivity to processing conditions. Bending tests indicated that elevated vat temperatures tended to degrade flexural properties, yet this degradation was mitigated in the case of the 37.5 wt% SiO2 composition. Tensile tests revealed a transition from viscoelastic to linear elastic behaviors with increasing SiO2 content, with high tensile strength sustained at low vat temperatures (<35 °C) when the SiO2 content exceeded 28.5 wt%. Thermogravimetric analysis supported these findings, indicating that increased SiO2 content ensured a more uniform dispersion, enhancing mechanical properties consequently. Thermal tests showed augmented thermal conductivity and diffusivity with reduced specific heat in SiO2-inclusive composites. This study provides guidelines for optimal PUMA/SiO2 composite utilization that emphasizes high SiO2 content and low vat temperature, offering comprehensive insights for high-performance ceramic composite fabrication in functional applications.

Dispersion, ionic bonding and vibrational shifts in phospho-aluminosilicate glasses.

Understanding the relationships between structure and properties of aluminosilicate glasses is of interest in magmatic studies as well as for glass applications as mechanical or optical components. Glass properties may be tailored by the incorporation of additional elements, and here we studied the effect of phosphate incorporation on refractive index and the degree of ionic bonding in aluminosilicate glasses. The studied glasses in the system SiO2-Al2O3-Na2O-P2O5 had a metaluminous composition (Al:Na = 1) with the content of SiO2 ranging from 50 to 70 mol% and of P2O5 from 0 to 7.5 mol%. Refractive index was measured at four wavelengths from visible to near-infrared and found to decrease both with increasing P2O5 content (at the expense of NaAlO2) and with increasing SiO2 content (by substitution of SiO4 for AlO4 groups). This trend correlated with a decrease in density while, additionally, the formation of Al-O-P bonds with an SiO2-like structure may account for this change. The degree of ionic bonding, assessed via optical basicity and oxygen polarisability, decreased with increasing P2O5 and SiO2 content. Despite the complexity of the studied glasses, oxygen polarisability and optical basicity were found to follow Duffy's empirical equation for simple oxide glasses. In the high frequency infrared and Raman spectra, band shifts were observed with increasing P2O5 and SiO2 content. They indicated changing average bond strength of the glass network and showed a linear correlation with optical basicity.

Impact of SiO2 doping on the structure and oil-water separation properties of a PVDF membrane: insights from molecular dynamics simulation.

Hybrid inorganic particles combined with polymers are widely used to modify the properties of polymer membranes. However, the mechanism by which particles affect membranes remains unclear. This study investigates SiO2-hybridized PVDF membranes through molecular dynamic simulation, focusing on the interaction between SiO2 clusters and PVDF chains. It examines the impact of varying SiO2 concentrations (3.5 wt%, 6.8 wt%, 9.9 wt%, 12.8 wt%, and 15.5 wt%) on membrane stability and structure. The results indicate that adding SiO2 can inhibit PVDF chain mobility in the membrane with minimal effect on fractional free volume (FFV), except for altering interactions between PVDF-PVDF, PVDF-SiO2, and SiO2-SiO2, thereby affecting the structure of hybrid membranes. The adsorption and diffusion behavior of water and oil molecules on these membranes were also studied. It was observed that the adsorption energy and diffusion coefficient initially increase and then decrease with increasing SiO2 concentration, reaching an optimum between 6.8 wt% and 12.8 wt%. This phenomenon is attributed to the ability of optimal SiO2 concentrations to create hydrophilic channels in PVDF membranes, enhancing water affinity and reducing oil affinity. Consequently, water permeation through the hybrid membrane is promoted, improving the efficiency of oil/water separation compared to pure PVDF membranes. This research contributes to understanding the function of adding inorganic particles to polymer membranes and provides insights for designing advanced functional hybrid membranes.

Development of the Al2O3-B2O3-SiO2 glass for thermal barrier coating

Glass coating is an important thermal insulation technique used in the aerospace industry that serves as a thermal protection system (TPS) to protect the inner layer at elevated temperatures. This work highlights the superb mechanical and thermal properties of the B2O3-SiO2 glass systems as a surface coating for space shuttle. In the B2O3-SiO2 system, the glass transition temperature raises from 650 °C to 750 °C with increasing SiO2 content and devitrification of the α-cristobalite phase. The Al2O3 addition in B2O3-SiO2 glass can increase the glass transition temperature from 750 °C to 1000 °C and inhibit the α-cristobalite phase. The phase transition from an unstable α-cristobalite phase to an amorphous phase was achieved at 10 wt% Al2O3-added specimens. This study demonstrates that the Al2O3-B2O3-SiO2 glass (ABS glass) exhibits thermally stable behavior, making it an effective thermal barrier coating at elevated temperatures.

Effective disposal of hazardous waste from non-ferrous waste recycling through thermal treatment

Hazardous wastes containing non-ferrous metals have significant value in recycling. However, the recycling process generates leaching residues (HWLR) with high levels of heavy metals, posing a risk to the environment. Based on the component characteristics of HWLR, silica residue (SR), and silicon tetrachloride cracking slag (STCS), the feasibility of co-thermal treatment for the efficient disposal of HWLR, SR and STCS was verified in this study. According to the SiO2–Na2O–CaO ternary system diagram, the melting point of the system decreases gradually with the appropriate increase in SiO2 content when the CaO/Na2O ratio in the system was determined to be about 2.33. When the theoretical liquid phase content of the mixed system of 100%, the thermal treatment temperature could be lowered to 1100 °C, which is significantly below the melting points of HWLR, SR, and STCS individually. The experimental results confirmed that thermal treatment at temperatures above 1000 °C effectively eliminated the leaching toxicity of Cu, Ni, Zn, Cr, Cd, and Pb in the mixed samples of HWLR, SR, and STCS, which can mainly be attributed to the formation of a glass network structure during the thermal treatment process. This study demonstrated that low-temperature melting treatments could efficiently and thoroughly solidify heavy metals in HWLR, SR, and STCS.

U-Pb Geochronology, Geochemistry and Geological Significance of the Yongfeng Composite Granitic Pluton in Southern Jiangxi Province

The Yongfeng composite granitic pluton, located in the southern section of the Nanling area, is composed of the Yongfeng and Longshi biotite monzonitic granites. In order to reveal the genesis of this composite granitic pluton and its relationship with mineralization, this study conducted zircon U-Pb dating, whole-rock major and trace element analysis, and biotite electron probe analysis. The results show that the Yongfeng composite granitic pluton is rich in silicon and alkali, weakly peraluminous, and poor in calcium and iron. It shows the enrichment of light rare earth elements and a significant fractionation of light and heavy rare earth elements. It also shows the enrichment of large ion lithophile elements and depletion of Ba, K, P, Eu, and Ti relative to the primitive mantle. The contents of TFe2O3, MgO, CaO, TiO2, and P2O5 are low and decrease with increasing SiO2 content. The Yongfeng composite granitic pluton does not contain alkaline dark minerals. Its average zircon saturation temperature is 776 °C, average TFe2O3/MgO is 4.81, and average Zr + Nb + Ce + Y is 280.6 ppm, which correspond to a highly fractionated I-type granite. The Yongfeng and Longshi granites were respectively formed at 152.0 ± 1.0 Ma–151.3 ± 1.1 Ma and 148.9 ± 1.2 Ma. They were formed in the extensional tectonic setting during the post-orogenic stage, under the control of the breakup or retreat of the backplate after the subduction of the Pacific Plate into the Nanling hinterland. The magmatic system of the Yongfeng composite granitic pluton is characterized by high fractionation, high content of F, high temperature, and low oxygen fugacity, which is conducive to mineralization of Sn, Mo, and fluorite.

Decoding subcontinental lithosphere processes: The key role of fractional crystallization in Central Andes monogenetic volcanism - Insight from El Negrillar volcanic field, Chile

Subduction zones are complex geodynamic settings in which volcanic arcs form due to the interaction between subducting slabs, water, and continental materials. Investigating this extensive Earth recycling system offers valuable insights into the exchange of materials between the crust and mantle. While previous research has primarily focused on analyzing polygenetic volcanoes to explore this interaction, monogenetic volcanic fields (MVF) present an opportunity to delve into the mechanisms operating within the upper and lower mantle. Monogenetic volcanoes are a class of volcanoes that are typically smaller in size but showcase a range of eruptive styles and compositions. These volcanoes can be found in various locations along the arc, including the main Central Volcanic Zone (CVZ) (arc-front volcanoes), and even far from the tectonic plate boundaries in the back-arc region (intraplate volcanism).We carried out a detailed geochemical study of El Negrillar (EN) MVF, located in the Central Andes main-arc, on the Altiplano-Puna Plateau's southwestern border. The volcanic field has 35 eruptive centers and a total of 86 eruptive phases originating from its three clusters: Northern, Central, and Southern. EN magmas range in composition from basaltic andesite to dacite and have produced over 6.8 km3 (DRE) of lava and pyroclastic material, which makes it the most voluminous volcanic field in the Central Andes, and therefore, an excellent example to study MVF in arc-systems. We have conducted an extensive study encompassing major and trace elements, as well as isotopic analysis using whole rock Sr-Nd-Pb. We also present an analysis of our results with available geochemical data from the back-arc and main-arc volcanoes, including other monogenetic volcanoes near EN (<80 km, EN's neighbors). The results revealed that EN magmas and their neighbors are strongly related and exhibit a clear similarity in major and trace element compositions and isotopic ratios, indicating a common source and origin of their melts. Our comparison across the arc surprisingly reveals similarities between EN and back-arc monogenetic volcanism. Both regions indicate geochemical signatures that do not support melting via slab metasomatism, typical of subduction zones. Instead, they show low Th/Ce (<0.1 ppm) and Ba/La (<30 ppm) and high Ce/Pb (>6 ppm), Ba/Th (>100 ppm), high 143Nd/144Nd > 0.51240, and La/Yb ratios at a given La/Sm compared to the main-arc polygenetic volcanoes. Interestingly, EN also exhibits adakite-like signatures with increasing SiO2 content (high Sr > 600 ppm, Sr/Y > 40, and high La/Yb > 20), a term used for igneous rock suites with chemical characteristics that are identical to those of adakites but produced through petrogenetic processes that do not include a slab component. We explore how fractional crystallization and crustal assimilation participate in the development of monogenetic volcanoes, and our findings underscore the significant influence of fractional crystallization on the monogenetic volcanic processes in the Salar de Atacama region. The geochemical changes observed in this area can be attributed to a combination of varying degrees of fractional crystallization within magmas generated through the partial melting of a garnet-enriched environment, which could be primary lower crust or partial melting of a peridotite mantle that has later equilibrated with garnet-bearing crustal melts.

UV-assisted stabilization of superhydrophobic nanofibrous membranes for waterproof, breathable and thermal insulation applications

Polyacrylonitrile (PAN)/polyurethane (PU)/hydrophobic silicon dioxide (SiO2) nanofibrous membranes were prepared by electrospinning combined with a UV-induced stabilization method. The PAN/PU/SiO2 membranes possessed excellent self-cleaning performance because the introduction of SiO2 nanoparticles endowed the nanofibrous membranes with high surface roughness and good hydrophobicity. In addition, SiO2 nanoparticles could also promote the waterproof performance of nanofibrous membranes because hydrophobicity improved and pore size decreased with the increase of SiO2 content. Water vapor transmission rate of the membranes decreased from 10.8 to 9.2 kg m−2 d−1 with increasing of SiO2 concentration because SiO2 nanoparticles could fill the spaces among the adjacent nanofibers. Reflectance to sunlight of the PAN/PU/SiO2 membrane was much higher than that of the PAN/PU membrane, indicating an obvious radiative cooling effect due to loading of SiO2 nanoparticles. This facile fabrication of fluorine-free superhydrophobic membranes provides advantages for potential applications in self-cleaning materials and versatile protective clothing.

Thermodynamic evaluation of viscosity behavior for CaO–SiO2–Al2O3–MgO slag systems examined at the temperatures range from 1500 to 1700 °C

This work showed an application of computational tools to understand systematically the behavior of viscosity on CSAM systems relevant to industrial uses. Consequently in this study, the viscosity experimental data obtained from the literature were compared with the thermodynamic calculated results via the software FactSage v.7.3 for melts in CaO–SiO2–Al2O3–MgO slag system with the range of compositions slags cover 0–100 wt% CaO, 0–100 wt% SiO2, 0–100 wt% Al2O3 and 0–15 wt% MgO at temperature ranges of 1500–1700 °C. Using open-source software in Python, the results of viscosity, liquid, and solid fraction of the slag, as a function of composition and temperature, are represented by multiple color maps and by iso-viscosity contours. The results of the viscosity values indicated that the effect of all the oxides in the CSAM slag system follows the well-known behavior trend observed in the literature. Viscosities of the slag were found to increase with increasing SiO2 contents and decrease with increasing basicities (high CaO). The increase in Al2O3 content increases the viscosity values. An increase of 0–15% MgO depolymerized the slag melt and decreases the viscosity. However, above 5% MgO content occur a decrease in the liquid zone (single phase) and a liquid fraction (two-phase region) of the slag. For a constant MgO concentration, the increase in temperature generates an expansion of low-viscosity zones associated with an increase in the liquid phase of the slag. From the comparison between the calculated and experimental viscosities data keeps up within 30% average relative deviation (Δ), the predictions are considered acceptable for viscosity in the CSAM slag system at high temperatures.

Photoluminescence properties of Lu2Si2O7:Eu3+ sol-gel thin films obtained using GLYMO as a silicon source

Thin films of Lu2Si2O7:Eu3+ were prepared via sol-gel methods and dip coating using lutetium nitrate and (3-Glycidyloxypropyl)trimethoxysilane as precursors, and ethanol and ethylene glycol were used as solvents. Acetylacetone was used as a stabilizer, and the pH was adjusted using acetic acid. Lu2Si2O7:Eu3+ films were deposited on silica quartz substrates and exhibited a monoclinic structure with preferential orientation along the [012] direction after heat treatment at 1000 °C. The film’ morphology was characterized by scanning electron microscopy, and the photoluminescence spectrum revealed a strong emission at 612 nm (5D0→7F2), corresponding to the Eu3+ ions, under 254 nm excitation. Notably, both the optical yield and decay time increased with increasing SiO2 content.

Structure, thermal and crystallization behavior of lead-bismuth silicate glasses

Lead-bismuth silicate glasses were synthesized using a standard melt-quenching technique, varying the compositions within the range of (80-x-y)PbO–(10+x)Bi2O3–(10+y)SiO2, where x and y were between 0 and 20 wt%. The glasses were subjected to comprehensive analysis, including X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, and dilatometry, to investigate their crystallization behavior, thermal properties, and structure. The obtained glass samples were confirmed to be amorphous through X-ray diffraction and scanning electron microscopy. Fourier-transform infrared spectra analysis indicated that the glasses consisted mainly of PbO4, BiO6, and SiO4 structural units. Differential thermal analysis curves were used to estimate the glass transition, crystallization, and melting temperatures, and the results showed increased thermal stability and decreased crystallization tendency with increasing SiO2 content in the glass. X-ray diffraction analysis was utilized to identify the specific crystalline phases that were formed after the glass was subjected to heat treatment. Dilatometric measurements demonstrated that the investigated glasses possess a wide range of coefficient of thermal expansion values (6.8–11.1 ppm/°C), a low glass transition temperature (335–475°С), and a low dilatometric softening temperature (355–505°С). These results have significant implications for developing oxide glasses with specific thermal characteristics suitable for a wide range of applications.