Incorporation Of Aluminum Research Articles

Generation of Acid Sites in Nanostructured KIT-6 Using Different Methods to Obtain Efficient Acidic Catalysts for Glycerol Acetalization to Solketal.

This study explored the preparation of pure silica KIT-6, as well as KIT-6 materials with an enhanced concentration of surface OH groups through aluminum incorporation or NH4F treatment. These materials with various contents of surface OH groups were subsequently modified via the post-synthesis grafting of sulfonic groups using 3-mercaptopropyltrimethoxysilane as a precursor, followed by oxidation to introduce acidic sites. The catalysts were thoroughly characterized using XRD, nitrogen adsorption/desorption, SEM-EDS, TEM, and FT-IR techniques to confirm their structural and chemical properties. The catalytic activity of acid-functionalized mesoporous silicas of the KIT-6 structure was further evaluated in the acetalization of glycerol to produce solketal. The results demonstrated a significant influence of the surface OH group concentration and acidic site density on catalytic performance, with KIT-6_F_SO3H showing the highest efficiency in glycerol-to-solketal conversion. This study provides valuable insights into the design of efficient catalytic systems for the valorization of biodiesel-derived glycerol into high-value chemicals, offering a sustainable approach to waste glycerol utilization.

Photovoltaic Efficiency Enhancement of Indium-Free Wide-Bandgap Chalcopyrite Solar Cells via an Aluminum-Induced Back-Surface Field Effect.

Wide-bandgap chalcopyrite materials are attractive candidates for a wide variety of energy conversion devices such as the top cell of tandem-type photovoltaic devices and photoelectrochemical water splitting hydrogen evolution devices. Nevertheless, simultaneous realization of high open circuit voltage (VOC) and high fill factor (FF) values has been challenging, and thus, the photovoltaic performance has been limited. In this article, high VOC and high FF values of wide-gap chalcopyrite CuGaSe2 thin-film solar cells are simultaneously demonstrated using an aluminum-induced back-surface field effect. An independently certified photovoltaic efficiency of 12.25% was obtained from an elemental In-free CuGaSe2:Al (bandgap energy ∼1.7 eV) solar cell (VOC: 0.959 V, short circuit current density: 17.64 mA cm-2, FF: 72.5%). In addition, an over 1 V-VOC CuGaSe2 cell (FF: 74.5%) was obtained even with the use of a conventional CdS buffer layer. Although incorporation of aluminum often leads to degradation of the chalcopyrite solar cell performance, the addition of a small amount of aluminum is found to be effective in enhancing wide-gap chalcopyrite photovoltaic performance.

Structural and optical evolution in CeO2 films induced by aluminum doping: A comprehensive study

This study investigates the impact of aluminum (Al) doping and oxygen vacancies on the structural, electronic, and optical properties of Cerium Oxide (CeO₂) films. The films were fabricated on glass substrates using the sol-gel spin coating method for both undoped and Al doped CeO₂. Theoretical insights from the DFT + U + V method further explore how Al doping and oxygen vacancies influence the electronic structure and optical behavior of ceria. Experimentally, Al doping was found to increase the lattice parameters and reduce the crystallite size without forming secondary phases. Raman spectroscopy revealed a shift to lower wavenumbers in Al-doped samples, while XPS analysis confirmed the presence of both Ce³⁺ and Ce⁴⁺ oxidation states, along with Al³⁺ and O2⁻ ions. Optical measurements showed a decrease in the optical band gap from 3.14 eV to 2.93 eV as the Al concentration increased to 5 %. Additionally, the optical dielectric constant slightly decreased, whereas optical conductivity improved with the incorporation of aluminum. Theoretical calculations show that oxygen vacancies were shown to reduce the band gap by introducing localized Ce³⁺ mid-gap states, while Al doping led to a gradual narrowing of the band gap without creating new states within it. The combination of Al doping and oxygen vacancies resulted in both further band gap narrowing and the appearance of mid-gap states. Optical property calculations revealed that both oxygen vacancies and Al doping reduced the intensity of the dielectric functions at 310 nm. Moreover, these two factors had opposing effects on the electron energy loss spectrum (EELS) at low energies: Al doping induced high-intensity peaks, while oxygen vacancies diminished these peaks.

Synthesis and characterization of lithium alumina silicate (LiAl(SiO3)2) from naturally sourced silica: a comparative study

This study investigates the synthesis and characterization of lithium aluminosilicate (LiAl(SiO3)2) using naturally sourced silica (NSS) from the Djamâa region in Algeria and compares it with laboratory-sourced silica (LSS). The synthesis was conducted using the sol–gel method and solid-state reactions with lithium carbonate, aluminum oxide, and SiO2. Characterization techniques included X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD analysis confirmed the crystalline structure of the synthesized lithium aluminosilicate, revealing distinct crystal phases: the NSS material exhibited a tetragonal spodumene-II phase. In contrast, the LSS material showed a hexagonal spodumene-III phase. The crystallite sizes were 21.96 μm for NSS and 22.14 μm for LSS, with crystallinity percentages of 60.77% and 57.55%, respectively. FTIR spectroscopy verified the successful incorporation of lithium and aluminum into the silica framework. SEM analysis provided detailed insights into surface morphology and particle size distribution, highlighting the uniformity of the materials. Specifically, the LSS material exhibited cylindrical spaces between particles, whereas the NSS material displayed spherical spaces.

On Morphology of Aluminum-Gallium Nitride Layers Grown by Halide Vapor Phase Epitaxy: The Role of Total Reactants' Pressure and Ammonia Flow Rate.

The focus of this study was the investigation of how the total pressure of reactants and ammonia flow rate influence the growth morphology of aluminum-gallium nitride layers crystallized by Halide Vapor Phase Epitaxy. It was established how these two critical parameters change the supersaturation levels of gallium and aluminum in the growth zone, and subsequently the morphology of the produced layers. A halide vapor phase epitaxy reactor built in-house was used, allowing for precise control over the growth conditions. Results demonstrate that both total pressure and ammonia flow rate significantly affect the nucleation and crystal growth processes which have an impact on the alloy composition, surface morphology and structural quality of aluminum-gallium nitride layers. Reducing the total pressure and adjusting the ammonia flow rate led to a notable enhancement in the homogeneity and crystallographic quality of the grown layers, along with increased aluminum incorporation. This research contributes to a deeper understanding of the growth mechanisms involved in the halide vapor phase epitaxy of aluminum-gallium nitride, and furthermore it suggests a trajectory for the optimization of growth parameters so as to obtain high-quality materials for advanced optoelectronic and electronic applications.

Arsenic and fluoride adsorption from multielement solutions onto aluminium modified montmorillonite

Groundwater is the primary source of drinking water worldwide. However, it might be harmful to consumer's health due to the presence of trace elements, such as arsenic and fluoride, commonly found in Latin American. The main objective of this study was to investigate the adsorption parameters of arsenic (As) and fluoride (F) dissolved in multielemental solutions containing vanadium (V) and boron (B), on aluminium-modified montmorillonite. To achieve that, a new adsorbent was synthesised and characterised using X-ray diffraction spectroscopy (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray (EDX) and N2 adsorption/desorption isotherm techniques. Adsorption efficiencies for As and F were evaluated in multielement solutions considering the simultaneous occurrence of B and V, naturally present in groundwater. Kinetic and equilibrium adsorption experiments were carried out in batch conditions for both, mono and multicomponent solutions. The adsorbent characterization indicated an effective incorporation of Aluminium (Al) into the aluminosilicate layers and at the external surface of the montmorillonite. The adsorption process for multielement solutions took a short time and the As adsorption was not affected by the presence of V, B, or F in the solution while F adsorption parameters were enhanced by the co-occurrence of the other species in the solution. The maximum adsorption capacities were 21 and 68 mg g−1 for As and F, respectively, in the presence of B and V, at low adsorbent dosage. The new material was also tested for groundwater samples collected from Buenos Aires province (Argentina) that were naturally contaminated with As, V, B, and F. The removal of these elements was lower when compared to synthetic solutions. However, the material's efficiency in removing the ions from natural groundwater was approximately 50%. These results suggest that the material could be used to develop filters to remediate arsenic and fluoride from naturally contaminated groundwater.

Epitaxial growth of α-(AlxGa1−x)2O3 by suboxide molecular-beam epitaxy at 1 µm/h

We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow α-(AlxGa1−x)2O3 films on (110) sapphire substrates over the 0 < x < 0.95 range of aluminum content. In S-MBE, 99.98% of the gallium-containing molecular beam arrives at the substrate in a preoxidized form as gallium suboxide (Ga2O). This bypasses the rate-limiting step of conventional MBE for the growth of gallium oxide (Ga2O3) from a gallium molecular beam and allows us to grow fully epitaxial α-(AlxGa1−x)2O3 films at growth rates exceeding 1 µm/h and relatively low substrate temperature (Tsub = 605 ± 15 °C). The ability to grow α-(AlxGa1−x)2O3 over the nominally full composition range is confirmed by Vegard’s law applied to the x-ray diffraction data and by optical bandgap measurements with ultraviolet–visible spectroscopy. We show that S-MBE allows straightforward composition control and bandgap selection for α-(AlxGa1−x)2O3 films as the aluminum incorporation x in the film is linear with the relative flux ratio of aluminum to Ga2O. The films are characterized by atomic-force microscopy, x-ray diffraction, and scanning transmission electron microscopy (STEM). These α-(AlxGa1−x)2O3 films grown by S-MBE at record growth rates exhibit a rocking curve full width at half maximum of ≊ 12 arc secs, rms roughness <1 nm, and are fully commensurate for x ≥ 0.5 for 20–50 nm thick films. STEM imaging of the x = 0.78 sample reveals high structural quality and uniform composition. Despite the high structural quality of the films, our attempts at doping with silicon result in highly insulating films.

Toward deeper ultraviolet detection: Atomic layer deposited amorphous AlGaOx thin film detector with its tunable optical properties and opto-electronic responses

Employing atomic layer deposition, AlGaOx films with varying Al concentrations (highest to 44% at.) were meticulously synthesized. Comprehensive characterization encompassing chemical composition, elemental depth distribution, structural clarity, and interface delineation unequivocally attested to the superior quality of the films. Optical properties were rigorously assessed using transmittance spectra and spectroscopic ellipsometry (SE), and optical constants across a broad spectral range (200–1000 nm) were determined through SE fitting. A consistent blue-shift in the absorption edge, observed in both the transmittance spectra and extinction coefficient, is attributed to the incorporation of aluminum. Detailed exploration via X-ray photoelectron spectroscopy fine scans of O 1s energy loss spectra and valence band analysis revealed that the evolution of the conduction band is instrumental in modulating the bandgap. To ascertain the viability for deep ultraviolet light detection, photodetectors based on AlGaOx were fabricated. Blue shifts in both photocurrent and response peak wavelength correlated with increasing Al content. In specific occasions, the AlGaOx-based detector has a responsibility of 0.05 A/W and 7×1013 detectivity of Jones. Remarkably, the detector demonstrates commendable on/off capability, characterized by fast rise and decay times of 0.26 s and 0.17 s, respectively. This study extensively examined the chemical, structural, and optical properties of amorphous AlGaOx films, alongside the optoelectronic capabilities of AlGaOx-based devices. Our research presented a viable strategy for enhanced deep ultraviolet detection, showcasing a successful implementation of amorphous bandgap engineering. This endeavor holds promise for future advancements in UV-detector development.

Comparative study on Al-SBA-15 prepared by spray drying and traditional methods for bulky hydrocarbon cracking: Properties, performance and influencing factors

Mesoporous aluminosilicates Al-SBA-15 with large pore sizes and suitable acid properties are promising substitutes to zeolites for catalytic cracking of bulky hydrocarbons without molecular diffusion limitation. The conventional processes to synthesize Al-SBA-15 are time-consuming and often suffer from low “framework” Al contents. Herein, Al-SBA-15 microspheres are synthesized using the rapid and scalable microfluidic jet spray drying technique. They possess uniform particle sizes (45–60 μm), variable surface morphologies, high surface areas (264–340 m2/g), uniform mesopores (3.8–4.9 nm) and rich acid sites (126–812 μmol/g) and high acid strength. Their physicochemical properties are compared with the counterparts synthesized using traditional hydrothermal and evaporation-induced self-assembly methods. The spray drying technique results in a higher incorporation of aluminum (Al) atoms into the silica “framework” compared to the other two methods. The catalytic cracking efficiencies of 1,3,5-triisopropylbenzene (TIPB) on the Al-SBA-15 materials synthesized using the three different methods and nanosized ZSM-5 are compared. The optimal spray-dried Al-SBA-15 exhibits the best performance with 100 % TIPB conversion, excellent selectivity (about 75 %) towards the formation of deeply cracked products (benzene and propylene) and high stability. The catalytic performances of the spray-dried Al-SBA-15 with varying Si/Al ratios are also compared. The reasons for the different performances of the different materials are discussed, where the mesopores, high acid density and strength are observed to play the most critical role. This work might provide a basis for the synthesis of mesoporous rich metal-substituted silica materials for different catalytic applications.

Growth and atomic oxygen erosion resistance of Al2O3-doped TiO2 thin film formed on polyimide by atomic layer deposition.

Polyimide (PI) coated with atomic layer deposition (ALD) thin films shows promising potential for applications in extreme environments. To achieve a high quality ultrathin ALD coating on the PI surface, Al-doped ALD-TiO2 (ATO) films were deposited on the alkaline hydrothermally activated PI surfaces. The nucleation and growth of ATO films were studied by XPS monitoring and SEM observation. The incorporation of aluminum introduced additional active sites that acted as a seed layer, promoting the adsorption and growth of titanium oxide. This effectively compensated for the defects in the TiO2 film, resulting in the formation of a continuously growing conformal film on the PI surface. After 200 ALD cycles, the ATO film deposited on PI exhibits excellent water vapor barrier properties and significant resistance to atomic oxygen (AO) erosion. When exposed to an AO flux of 1.4 × 1022 atom per cm2, the erosion yield of the PI coated with 200 ALD cycles of ATO film was as low as 2.4 × 10-26 cm3 per atom, which is two orders less than that of the standard polyimide-ref Kapton® film.

Influence of aluminum incorporation and aqueous conditions on metal ion release of high-Ni transition metal oxide nanomaterials

Developing a materials perspective of how to control the degradation and negative impact of complex metal oxides requires an integrated understanding of how these nanomaterials transform in the environment and interact with biological systems.

Low temperature dielectric studies of aluminum doped tin oxide nanoparticles

This study presents a facile sol-gel route for synthesizing pristine and Al-doped SnO2 nanoparticles. The phase purity of the synthesized nanoparticles was confirmed by powder X-ray diffraction (PXRD), revealing a tetragonal cassiterite structure for all samples. The crystallite size, determined by using the Scherrer equation and Willamson-Hall plot, ranged from 9.66 nm to 25.75 nm and exhibited an increasing trend with increasing doping concentration. Raman spectroscopy further corroborated this structural identification. The incorporation of aluminum (Al) into the tin oxide matrix was validated by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. UV–visible spectroscopy revealed a reduction in the bandgap from 3.6 eV to 3.2 eV upon Al doping, attributed to the decreasing lattice strain with increasing Al content and other underlying mechanisms. The dielectric properties, including dielectric constant, dielectric loss, and AC conductivity, were examined as a function of frequency and doping concentration within the temperature range of 100 K–400 K. These properties exhibited an increasing trend up to 6 % Al doping. Interestingly, the 8 % doped sample exhibited the lowest dielectric loss and the highest AC conductivity, making it a promising candidate for applications in high-frequency electronics, energy storage, and ferroelectric devices.

Self-cleaning performance of autoclaved photocatalytic cement pastes: Insights into phase composition, microstructure and aluminum incorporation in C–S–H

This study attempts to comprehend mechanisms that enhance the photocatalytic properties of autoclaved cementitious pastes. The photocatalytic self-cleaning performance, phase composition, microstructure, optical properties, and silicate chain properties are characterized and analyzed. The results indicate that the silica source and alumina play significant roles in the evolution of phase composition and microstructure, which consequently affects the photocatalytic self-cleaning performance. The impacts of in-situ generated cement hydrates on the photocatalytic performance of cementitious materials are discussed for the first time, as well as the mechanisms governing the different morphologies of C–S–H crystals with the addition of different oxides. For the first time, the role of aluminum incorporation in the C–S–H network and major factors at different stages on the photocatalytic performance of cementitious materials are discussed. Finally, a systematic understanding of the photocatalytic properties of autoclaved cementitious materials is established. These results provide insights into the development of photocatalytic cementitious materials with tailored performances.

Constitutive description, processing maps, and un-explored deformation mechanisms of pure Mg and Mg-6Al(wt%) alloy under hot compression

This study investigates the hot deformation behavior and final microstructure features with and without aluminum (Al) incorporation in magnesium (Mg). To this end, pure Mg and Mg-6Al(wt%) alloy were subjected to high-temperature compression and systematically analyzed the flow stress, activation energies, Zener Hollomon parameters, processing maps, and microstructure evolution, including geometrically necessary dislocations under different g vectors. These all were in an excellent relationship with each other. The microstructure analysis greatly validated the processing map parameters. Amazingly, we have attained an unexplored grain boundary sliding phenomenon under high-strain rate compression in pure Mg. This phenomenon is only reported in high-temperature tensile specimens, especially for those who attained superplasticity. Unfortunately, the mechanism attained at a strain rate (10 s−1) and temperature (573 K), which is referred to as an unstable region. Above the temperatures of 573 K, the Mg lost thermal stability, and an abrupt increase in grain size happened (3–40 µm). The addition of Al restricted the abnormal grain growth at elevated temperatures and retained grain size within < 10 µm. The higher geometrically necessary dislocation density and increase in grain boundary energy are the potential reasons for the thermal stability of Mg-Al alloy. Therefore, incorporating the Al not only enhances the formability of Mg but also provides many different stable zones, thermal stability and increases the power dissipation efficiency.

Effect of conditions on wet carbonation products of recycled cement paste powder

Wet carbonation is deemed a successful approach to recycling waste concrete powder. Controlling the growth and properties of products in the recycled cement paste powder (CPP) is highly dependent on the wet carbonation conditions. Therefore, this study aims to examine the effect of wet carbonation parameters on wet carbonation products in CPP. The wet carbonation of CPP resulted in mixed distribution of silica gel and CaCO3 without significant layering on the CaCO3. In contrast, silica gel covered the outside of the CaCO3 in the case of dry carbonation. Increasing the temperature from 25 °C to 80 °C promoted and accelerated the crystallization and growth of amorphous CaCO3, increased the crystallite size of CaCO3 by 1.1–5.1 nm, and favored the formation of aragonite and vaterite; however, it also led to a significant crystal defect and/or distortion within CaCO3. Higher temperatures also promoted silica gel formation and increased its polymerization degree by 68.2%. On the other hand, increasing the CO2 flow rate from 3 L/min to 5 L/min facilitated the crystallization and growth of CaCO3 and contributed to the increase in the crystallite size of CaCO3 by 3.0–6.6 nm. Higher CO2 flow led to the incorporation of aluminum into silica gel and resulted in the transformation of its gel pores into capillary pores. The findings of this study contribute to a better understanding of the best experimental parameters to achieve a more efficient and effective concrete waste recycling process.

An approach to improve corrosion resistance in electro-galvanized Zn-Al composite coating by induced passivity

In the current work, zinc and zinc-aluminum nano-composite was electro-galvanized onto mild steel at specified current densities from a sulfate bath. The incorporation of aluminum was found to enhance the corrosion resistance (0.0008 to 0.0003 mm/yr) as well as passivity of the deposits as compared to pure zinc deposition. Hence, attempts were made to analyze the effect of aluminum addition on the passive film and its protective nature by using several techniques including SEM, XRD, Mott- Schottky (MS), Electrochemical Impedance Spectroscopy. The results proved that the films were of protective nature and are of n-type semiconductor properties with adequate defect densities/charge carriers.

On the factors controlling the incorporation of aluminium within titanites: a case study from medium pressure calc-silicate granulites in parts of the East Indian shield

On the factors controlling the incorporation of aluminium within titanites: a case study from medium pressure calc-silicate granulites in parts of the East Indian shield

Study of the Properties of CdS:Al (R = [Al3+]/[Cd2+] = 0.30, 0.40, 0.50) Thin Films Grown by the CBD Method in an Ammonia-Free System.

CdS:Al thin films were fabricated on a glass substrate using the CBD method. The effect of aluminum incorporation on the structural, morphological, vibrational, and optical properties of CdS thin layers was investigated by X-ray diffraction (XRD), Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and UV-visible (UV-vis) and photoluminescence (PL) spectroscopies. XRD analysis of deposited thin films confirmed a hexagonal structure with a preferred (002) orientation in all samples. The crystallite size and surface morphology of the films are modified with aluminum content. Raman spectra exhibit fundamental longitudinal optical (LO) vibrational modes and their overtones. Optical properties were studied for each thin film. Here, it was observed that the optical properties of thin films are affected by the incorporation of aluminum into the CdS structure.

Surface modified mesoporous KIT-5: A catalytic approach to obtain butyl levulinate from starch

Biomass is the only renewable organic material that has high energy content. Due to the significant amount of biomass resources, especially crop residues, the valorization of biomass to fuel or fuel additives have received more attention. In the present paper, biomass-derived butyl levulinate was prepared from starch in the presence of Al-modified mesoporous KIT-5 silica to improve its catalytic activity. Accordingly, the acidity character of KIT-5 was improved by two methods: wetness impregnation and in situ incorporation of aluminum. The essential properties of these catalysts were characterized by different techniques including N2 adsorption-desorption analysis, ICP-OES, FT-IR, and Pyridine-FT-IR analyses, XRD, SEM, TEM. A series of important parameters influencing the reaction yield was thoroughly investigated. Under the optimized conditions (230 °C, 10 h, 30 mg catalyst, and 70 mg starch), 31% n-butyl levulinate yield and 74% starch conversion were obtained, respectively. Finally, the selected catalyst was regenerated and reused in starch valorization reaction for four successive runs.

Alloying‐Triggered Phase Engineering of NiFe System via Laser‐Assisted Al Incorporation for Full Water Splitting

AbstractIt is challenging to design one non‐noble material with balanced bifunctional performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for commercial sustainability at a low cost since the different electrocatalytic mechanisms are not easily matchable for each other. Herein, a self‐standing hybrid system Ni18Fe12Al70, consisting of Ni2Al3 and Ni3Fe phases, was constructed by laser‐assisted aluminum (Al) incorporation towards full water splitting. It was found that the incorporation of Al could effectively tune the morphologies, compositions and phases. The results indicate that Ni18Fe12Al70 delivers an extremely low overpotential to trigger both HER (η100=188 mV) and OER (η100=345 mV) processes and maintains a stable overpotential for 100 h, comparable to state‐of‐the‐art electrocatalysts. The synergistic effect of Ni2Al3 and Ni3Fe alloys on the HER process is confirmed based on theoretical calculation.