Carbothermal Reduction Method Research Articles

Catalytic transfer hydrogenolysis of lignin derived aromatic ethers over MOF derived porous carbon spheres anchored by Ni species

The efficient hydrogenolysis of CO ether bonds in lignin is the key for producing bio-oil and high-value chemicals. In this work, we synthesized a series of Ni-MOF-derived porous carbon spheres anchored Ni catalysts (Ni/C-x-T) with different metal/ligand molar ratios and calcination temperatures through solvothermal and carbothermal reduction method, and evaluated their catalytic transfer hydrogenolysis (CTH) performance for lignin model compounds using isopropanol as H-donor. The Ni/C-2-400 catalyst exhibited the excellent CTH performance, affording almost 100 % conversion of 2-phenoxy-1-phenylethanol even at a low reaction temperature of 120 °C. It was worth noting that the further hydrogenation of hydrogenolysis products phenol and ethylbenzene could be controlled by adjusting the reaction conditions, achieving phenol and ethylbenzene as main products at 120 °C, cyclohexanol and ethylbenzene at 140 °C, and cyclohexanol and ethylcyclohexane at 200 °C for 4 h. Based on the characterization results, the high catalytic activity of Ni/C-2-400 was attributed to the good dispersion and small particle size of metal Ni particles. Mechanistic studies showed that the cleavage of CO ether bonds was the main reaction pathway, and high temperature helped accelerate hydrogenolysis and subsequent hydrogenation. Moreover, the Ni/C-2-400 catalyst had good stability and applicability to other model compounds. This work could provide some help for the upgrading of lignin and its derivative.

SiC@Co-CNT composites with tunable electromagnetic parameters for microwave absorption

Silicon carbide (SiC) is considered as a potential wave-absorbing material, but pure SiC has a low dielectric constant and no magnetic loss. In this paper, (cobalt loaded carbon nanotubes) Co-CNT is chosen as the composite material. The conductivity of CNT is utilized to improve the dielectric properties of SiC, while the magnetic permeability of Co can enrich the loss mechanism of SiC. SiC composite cobalt loaded carbon nanotubes (SiC@Co-CNT) composites were successfully prepared by using the carbothermal reduction method. The electromagnetic parameters of the composites are regulated by adjusting the Co content, which in turn optimises the microwave absorbing performance of the composites. The results show that the microwave absorbing performance of the SiC@Co-CNT composite is significantly improved. In particular, when the Co content is 20 wt%, the reflection loss (RL) value is −57.67 dB at 10.1 GHz and 2.63 mm, and the effective absorption bandwidth is 3.75 GHz (8.05–11.8 GHz). This work provides new research ideas for the application of SiC in the field of absorbing materials.

Investigation into Recycling of Iron Oxide Scale on H13 Steel by Low‐Temperature Carbothermal Reduction Method

The current method for recovering iron oxide scale in the steel industry is not economically optimal, especially for high‐alloy scales found in alloyed steel. This study focuses on iron oxide scale containing valuable metals like chromium (Cr), molybdenum (Mo), and vanadium (V). The required carbon addition is calculated based on the iron and chromium oxides in the scale. The effects of varying carbon additions and reduction temperatures on reduction efficiency are thoroughly examined. Kinetic studies show that as temperature and carbon increase, the rate‐limiting step shifts from interfacial diffusion to interfacial reaction. Reduction experiments assess carbon utilization, metallization rate, deoxidation rate, and removal of harmful elements. Results show that high temperatures hinder sulfur (S) and phosphorus (P) removal, and excess carbon reduces carbon utilization efficiency. Optimal conditions are a carbon ratio of 0.2174 and a temperature of 1150 °C. The carbothermic reduction product requires further refinement through conventional ladle slag systems to meet the quality standards for metallic materials. Over 65% of alloying elements are recovered, though phosphorus content remains slightly higher than in finished alloy steel. The materials from this study are suitable as high‐quality intermediates for alloy steel production.

The waste recycling approach for enhancing wastewater sludge dewaterability by using iron-mud (IM)/sawdust derived carbon composite

The dewaterability of wastewater sludge by the solid waste of iron-mud (IM)/carbon (IMS) composite prepared via the in-situ carbothermal reduction method was systematically studied in this paper. It investigated the effects of different IMS materials, IM dosages and stirring speeds on sludge dewaterability, including water content (WC), capillary suction time (CST), extracellular polymeric substances (EPS) contents and particle size. The results of dewatering tests demonstrated that IMS materials significantly enhanced sludge dewaterability, resulting in a reduction of 39.85 % in CST and 13.26 % reduction in WC in the dewatered sludge under optimum condition (IMS-3 dosage of 8 % dry solids; stirring speed of 250 r/min for 30 min). Electron paramagnetic resonancec (EPR) and scavenging experiments were conducted to better understand the dewatering process mechanism. This results indicated that both hydroxyl radicals (•OH) and superoxide radicals (•O2−) collaborate during the dewatering process. Furthermore, analysis were performed on the particle size of sludge flocs and scanning electron microscopy (SEM) imaging of sludge morphology to reveal the synergistic effects of IMS treatment. A two-step mechanism involving oxidation and Fe(III)-based re-flocculation maybe explain the synergistic effect of IMS treatment. This novel recycle-based IMS composite approach offers a new management strategy for industrial solid wastes while enhancing the sludge dewatering efficiency.

Hydrophilic Ultra-Fine SiC Nanowires Enhance the Performance of Hydrated Salt Phase-Change Energy Storage Materials.

In this study, ultrafine linear nanostructured SiC with high wettability and large specific surface area were synthesized via the carbothermal reduction method. These nanowires were impregnated with Na2SO4 ⋅ 10H2O, CaCl2 ⋅ 6H2O, MgCl2 ⋅ 6H2O, and CaMg2Cl6 ⋅ 12H2O to obtain composite phase change materials (CPCMs), which demonstrated improved phase separation and significantly reduced supercooling. In particular, the supercooling degree of CaCl2 ⋅ 6H2O was minimized to 0.1 °C. The SiC nanowires effectively prevented issues of dehydration and deliquescence in hydrated salts. The thermal storage capacities of the CPCMs exceeded 90 %, with Na2SO4 ⋅ 10H2O and MgCl2 ⋅ 6H2O reaching 107.10 % and 103.35 %, respectively. Furthermore, the CPCMs exhibited greater sensitivity to changes in temperature compared with the pure hydrated salt phase change materials (PCMs). These results indicate that ultra-fine SiC nanowires can act as a versatile carrier for hydrated salt PCMs at low and intermediate temperatures.

Kinetic modelling of carbothermal reduction of nickel oxide (NiO): Design of Experiments (DOE) approach

ABSTRACT This study presents a mathematical model to evaluate the kinetics of the carbothermal reduction of NiO using graphite. Based on the shrinking core theory, the model was validated against experimental data obtained under both isothermal and non-isothermal conditions. The shrinking core model for isothermal and non-isothermal conditions was created using MATLAB software for the kinetic modelling of the reduction process to determine the extent of reduction and the reaction rate. The kinetics were mathematically modelled from independently measured physical and thermodynamic properties of the reaction system and experimentally measured properties. The carbothermal reduction method was effective in producing Ni metal from NiO and was considered an established basis for evaluating the modelling aspect of the solid–gas system. The experimental investigation of carbothermal reduction was conducted using a statistical design of experiments (DOE), employing a two-level factorial design (23). The experiments were performed for a range of different factors, namely reduction temperature (800-1000°C), reduction time (1-2 h), and the molar ratio of graphite to NiO (0.5-1.5) on the extent of reduction. The extent of reduction increases with increasing reduction temperature, reduction time, and molar ratio of C to NiO. The highest extent of reduction (77.9%) was achieved at a reduction temperature of 1000°C, 2 h of reduction time, and the molar ratio of C to NiO as 1.5. The X-ray diffraction (XRD) studies confirmed the formation of Ni at a lower reduction time, but the intensity of the Ni phase was higher for a longer duration of reduction. SEM-EDS analysis of the reduced products confirmed the formation of Ni in the form of elongated and larger grains, along with traces of residual or unreacted carbon. The predicted extent of reduction is then compared with the experimentally measured results. The kinetic modelling results proved that both isothermal and non-isothermal shrinking core models showed similarity and significant closeness to the experimental data. The deviation between the experimental and model results could be due to the varying geometry and porosity of the reactants and intermediate products.

Optimization of process parameters for preparing AlN nanopowders by combining carbon-containing droplet combustion and carbothermal reduction methods

In this research, AlN nano-powders were prepared by combining carbon-containing droplet combustion (CCDC) and carbothermal reduction (CR) methods. Firstly, Al2O3+C mixed precursor was synthesized by the CCDC method, and then AlN nano-powder was obtained by the carbothermal reduction of this CCDC precursor. The effects of urea and glucose contents, ignition temperature, and combustion atmosphere on precursors and AlN powders were studied in detail. The results showed that with the molar ratio of urea to aluminum nitrate (U/A) of 3, the atomic ratio of carbon to aluminum (C/Al) of 6, and the ignition temperature at 800 °C under air atmosphere, the prepared precursor was composed of hollow and spherical structure particles exhibiting rough and porous surface morphology with high specific surface area (SSA) (41.4 m2/g). AlN nano-powders obtained by the carbothermal reduction of this precursor were found to be consisted of fine particles with the size of 20–30 nm with high SSA of 39.9 m2/g.

CNTs/lamellar VSe2/Fe3O4 self-assembled a variety of unique three-dimensional multilayer interface structures and microwave absorption properties

Fabrication of microwave absorption (MA) materials of matched small thickness, low density, broad effective absorption bandwidth (EAB), as well as high absorption performance remains a technical challenge to be solved today. In this paper, three-dimensional (3D) VSe2/CNTs/Fe3O4 ternary composites with a variety of self-assembled structures were fabricated by a two-step hydrothermal and one-step carbothermal reduction method. Via varying the content of Fe3O4 in the composites, different 3D multilayer interfacial structures, such as star fruit-, bitter melon-, goldfish-, starfish-, peony- and chrysanthemum-shaped structures were self-assembled, and excellent MA absorption characteristics were obtained. The best reflection loss (RLmin) was −50.96 dB at 1.8 mm thickness. The maximum EAB was 4.93 GHz at 2.0 mm thickness. Carbon nanotubes mainly contributed to conduction and polarization losses. In situ generated VSe2 nanosheets and Fe3O4 nanoparticles promoted the assembly of multilevel interfacial structures, thus contributing to interfacial polarization loss and dipole polarization loss. Fe3O4 also created magnetic losses. This study lays the foundation for fabricating highly efficient MA materials in special self-assembled heterostructures with ternary synergistic effects at the nanoscale.

Tunable Luminescent Properties and Multifunctional Imaging Applications of (Gd1-xRx)2O2S:Tb3+ (R = Y, La) Phosphor and Screen.

Gd2O2S:Tb3+ phosphor screens are widely used in image intensifiers, computed tomography, and neutron imaging. To improve the luminescent properties and thermal stability, (Gd1-xRx)2O2S:yTb3+ (R = Y, La) (x = 0, 0.05, 0.15, 0.25, and 0.35; y = 0.02, 0.04, 0.06, 0.08, and 0.10) phosphors were successfully prepared by the carbothermal reduction method. The luminescent spectra showed that the optimum concentrations of Tb3+ ions were 6 and 4 mol % when excited by 292 nm UV light and cathode ray, respectively. The emission wavelengths mainly peaked at 489 and 544 nm. It was found that the introduction of Y3+ ions could improve the luminescent intensity, and the luminescent intensity of (Gd1-xYx)2O2S:0.06Tb3+ was the highest at x = 0.25, while La3+ ions played the opposite role. Then, the thermal stability also improved, and the emission intensities of Gd2O2S:0.06Tb3+, (Gd0.75Y0.25)2O2S:0.06Tb3+, and (Gd0.75La0.25)2O2S:0.06Tb3+ phosphors at 423 K decreased to 66.22%, 68.23%, and 76.10% of the emission intensities at 303 K, respectively. Finally, the (Gd0.75Y0.25)2O2S:0.06Tb3+ phosphor screen was successfully prepared by the gravity deposition method and could be well imaged under UV light and cathode ray excitation with a CMOS camera. In summary, this study demonstrates that (Gd1-xRx)2O2S:Tb3+ (R = Y, La) is a phosphor with excellent luminescent and thermal stability properties and has great potential for application in the field of low-level-light night vision, nondestructive testing, and medical imaging.

MoC nanoparticles decorated carbon nanofibers loaded with Li2S as high-performance lithium sulfur battery cathodes

Lithium sulfur (Li-S) batteries have broad development potential in the field of electrochemical energy storage due to their high theoretical specific capacity, low cost, and environmentally friendly. However, the notorious shuttle effect of lithium polysulfides (LiPSs) during cycling process severely limits the performance improvement of Li-S batteries. In this work, carbon nanofibers (CNFs) decorated by MoC nanoparticles have been successfully established through electrospin combined with carbothermal reduction method. The effect of calcination temperature and MoC loading amount on the catalytic activity on LiPSs, as well as the electrochemical performance have been first investigated in detail. Based on the visualized adsorption and LiPSs conversion kinetics testing, the CNFs@MoC composites with 37 wt% MoC loading (CNFs@MoC-37 %) are confirmed to be the optimized sample. By using liquid-phase impregnation to load Li2S onto the CNFs@MoC-37 % composites to act as cathode, the assembled cells can achieve a reversible capacity of 941 mAh g−1 and 751 mAh g−1 at the current density of 0.1C and 1C respectively. The reversible capacity can still maintain at 550 mAh g−1 at 1C after 500 cycles, corresponding to the capacity decay rate of 0.054 % per cycle.

Synergistic magnetic Cu-Fe catalysts on N-doped biochar for efficient alkali lignin catalytic depolymerization into monophenols

Alkali lignin, a major by-product of papermaking, poses disposal challenges, hindering the full valorization of lignocellulose in sustainable biorefineries. One-pot lignin catalytic depolymerization (LDP) in water offers a promising route for producing valuable phenolic compounds. This study reports the successful synthesis of in-situ N-doped biochar supported CuxFey catalysts (CuxFey/N-BC) via a one-step carbothermal reduction method, enabling LDP in water without the need for external hydrogen, additives, alcohol solvent, or co-catalysts. Notably, the Cu5Fe1/N-BC could achieve remarkable catalytic performance under mild reaction conditions (280 °C, 6 h, 18 mL water), yielding 80.84±2.23 mg/g of monophenol, 56.17±1.32 % of bio-oil, and a lignin conversion rate of 80.66±0.73 %. This significantly surpassed the performance of monometallic catalysts and bare biochar. The synergistic effects of intermetallic interactions and nitrogen doping were proposed to create abundant active sites and rich pore structures, promoting efficient LDP reactions. Furthermore, the Cu5Fe1/N-BC exhibited excellent recyclability, with minimal activity loss (2.79 %) per cycle, due to its strong magnetism and favorable interactions. Mechanism investigation revealed that the Cu5Fe1/N-BC efficiently cleaved the C-O and C-C bonds in lignin, and led to the targeted production of guaiacyl phenols. This study provides valuable insights and practical strategy for valorizing lignin into valuable chemicals, advancing its utilization in various applications.

Formation mechanism and luminescence properties of silicon carbide nanowires with core-shell structure

For the preparation of SiC nanowires (SiC NWs) by carbothermal reduction, it is of great significance to study the formation mechanism of sic nanowires for process optimization and the controllable preparation. Although first-principles molecular dynamics (FPMD) can simulate systems of hundreds of atoms on a picosecond time scale, the results of FPMD are still insufficient to elucidate the formation mechanism of core-shell SiC nanowires. To make up this deficiency, this article has conducted Deep Potential Molecular Dynamics (DPMD) simulation on nanoseconds timescales with near FPMD accuracy for systems containing thousands of atoms, the results more concretively show the formation process of core-shell SiC nanowires. DPMD simulation results show when CO molecules react with SiO molecules, CO molecules are wrapped by SiO molecules to form agglomerates, SiO molecules in the agglomerates that can come into contact with the wrapped CO molecules will react with wrapped CO molecules to form the SiC core, and SiO molecules that in the outer layer of the agglomerates will disproportionate into the amorphous SiO2 shell. Furthermore, the formation mechanism of SiC nanowires was validated in combination with thermodynamics and experimental methods. Thermodynamic results show that vacuum conditions are favorable for the formation of SiO and CO and lower the temperature of SiC preparation. Finally, the core-shell structure of SiC NWs with good luminescence properties were successfully prepared by carbothermal reduction method using carbon black and silicon dioxide as raw materials under the pressure of less than 5 kPa.

Growth mechanism of TaC coating on carbon fibers via molten-salt-assisted carbothermal reduction method

Reactive melt infiltration (RMI) is considered suitable process to prepare C/SiC composites with low porosity and near-net shape. However, because of inevitable reactions between molten metal and carbon fibers, mechanical properties of C/SiC composites may be affected. In this work, continuous TaC coating was successfully prepared on the surface of carbon fibers using molten salt method. Effects of temperature and holding time on microstructure, bonding configurations, and crystal structure of TaC coating were systematically investigated. With increase in temperature and time, TaC grains grew larger and TaC coating became thicker, with growth rate constant of about 3.05 × 10−17 m2/s. TaC coating prepared at 1200 °C for 60 min was continuous, uniform and well bonded with carbon fibers, and the main growth direction of TaC grains was [111]. Activation energy for formation of TaC coating was 295.48 kJ/mol. From a dynamic perspective, diffusion behavior of Ta ions through reaction interface was controlling step for formation of continuous TaC coating.

A process for preferential recovery of lithium and manganese from spent NCM by vacuum carbothermal reduction method

In this study, a process was developed for the preferential recovery of lithium and manganese from spent ternary lithium batteries using the vacuum carbothermal reduction method. Firstly, the electrolyte and PVDF in the cathode and anode wafers of the spent ternary lithium batteries were removed. Subsequently, lithium in the cathode powder was preferentially recovered under vacuum conditions using the anodic powder as a reducing agent. The findings show that at 1623 K and 25 %for 2 h, the reduction process generates Li2O, (NiO)m-(MnO)n, Ni, and Co as the ultimate products. Reduction roasting enables the preferential extraction of 99.99 % Li and 99.82 % Mn, which condense on the condensation tray as Li2O and MnOx, while Ni and Co are present in the residue as oxides and monomers. In summary, the whole process of the vacuum carbothermal reduction method achieves efficient extraction of Li and Mn while avoiding the subsequent recovery of Ni, Co, and Mn. It also minimizes Li loss and Mn contamination during the recovery of Ni and Co. Additionally, by utilizing the cathode material from waste LIBs. This process realises the use of waste for waste management, resulting in significant cost savings in recycling and reducing environmental harm.

Boosting proton intercalation via sulfur anion doping in V2O3 cathode materials towards high capacity and rate performance of aqueous zinc ion batteries

Aqueous zinc-ion batteries (ZIBs) are a prospective solution for grid-scale energy storage. V2O3 has emerged as a promising cathode candidate with reversible two-electron redox capability for ZIBs. However, it still faces problems such as poor electronic conductivity and sluggish ion embedding kinetics. Herein, we report sulfur anion-doped V2O3 with tunneled structure based on a facile carbothermal reduction method, which can exhibit the significant impact of sulfur anion-doping on proton storage in vanadium-based cathode materials for high capacity and rate performance of ZIBs. The covalent bonds in S-V-O lead to accelerated charge transfer and elevated electronic conductivity. In-situ X-ray diffraction, synchrotron-based X-ray absorption spectroscopy combined with DFT calculations demonstrate that S doping effectively diminishes the adsorption and embedding energies of H+ in V2O3 and greatly boosts proton insertion kinetics. The co-intercalation of H+/Zn2+ helps compensate for the deficiency of Zn2+ insertion/extraction kinetics. Amorphous transition of crystalline V2O3 initiated from initial charging is conducive to mitigating stress and retaining stable cycling capacity. The typical sulfur-doped V2O3 achieves remarkable capacity (470.4 mAh·g−1 at 0.5 A·g−1), excellent rate capability (264.6 mAh·g−1 at 10 A·g−1) and stable long-term cyclability (231.2 mAh·g−1 at 10 A·g−1 after 2000 cycles). Furthermore, the corresponding pouch cells can deliver 26 mAh at 1 A·g−1 after 250 cycles, holding great potential for practical applications.

Li2ZrO3 coated LiFe0.4Mn0.6PO4/C with enhanced cycling performance at elevated temperature for lithium-ion batteries

Lithium iron manganese phosphate (LFMP) is regarded as one of the most promising cathode materials for lithium-ion batteries due to its high energy density and low cost. However, the Jahn-Teller effect of Mn3+ inevitably causes the dissolution of Mn during the cycling process, is accompanied by a severe decrease in the discharge capacity and a decline in capacity retention rate, which is more serious at elevated temperature. Here, the LiFe0.4Mn0.6PO4/C (LFMP-0LZO) cathode material is prepared via carbothermal reduction method, and its surface is modified by Li2ZrO3 (LFMP-1LZO) to enhance the surface stability and improve the cycling performance at room temperature and elevated temperature. The residual capacities of LFMP-0LZO sample is 113.7 mAh g−1, with a capacity retention rate of only 75.55 % after 150 cycles at 55 °C and a current density of 1C (1C = 170 mA g−1), while the discharge capacity of 1 wt% Li2ZrO3-coated material (LFMP-1LZO) under the same conditions is 134.85 mAh g−1, with a higher capacity retention rate of 87.49 %. Furthermore, a series of characterization experiments show that the surface modification of LiFe0.4Mn0.6PO4/C with Li2ZrO3 can effectively inhibit the side reaction between the electrode/electrolyte interface and reduce the dissolution of Mn in the active substance.

Facile synthesis of rare earth ions doped LiSr4(BN2)3 phosphors for white light-emitting diodes

Rare earth ions doped nitride is a kind of excellent phosphor for phosphor-converted white light-emitting diodes (WLEDs). However, the critical synthesis condition limits the application of nitrides in WLEDs. In this work, we develop a modified carbothermal reduction and nitridation method to synthesize rare earth ions doped LiSr4(BN2)3 phosphors. The crystal structure, morphology and photoluminescence properties of the obtained phosphors were systematically investigated. Intense blue emitting is achieved in Ce3+ doped LSBN with internal quantum efficiency (IQE) of 85.7 % and external quantum efficiency (EQE) of 45.5 %. The emitting color can be tuned from blue to green by co-doping with different amounts of Tb3+ ions. Near unit IQE is achieved in LSBN:Ce 0.5 mol%, Tb 5 mol%. The obtained phosphors exhibit excellent thermal and color stability at temperature range of 300–523 K. A WLED is fabricated by coating LSBN:Ce 0.5 mol%, Tb 5 mol% and commercial CaAlSiN3:Eu2+ on a 370-nm chip. The rare earth ions doped LSBN phosphors with high QE and excellent thermal stability in this work are promising candidates for WLEDs

Preparation and characterization of zirconium carbide nano powder by hydrothermal and carbothermal reduction methods

A hydrothermal method was employed to synthesize the precursor of nano-zirconium carbide, which was subsequently heat treated at high temperatures under vacuum to obtain finely dispersed nanometer-sized zirconium carbide powder through a carbothermic reduction reaction. Scanning Electron Microscopy (SEM) was utilized to examine the microstructure of the precursors obtained under different hydrothermal conditions and carbon contents. The effects of different heat treatment temperatures on the microstructure of the products were analyzed. Transmission Electron Microscopy (TEM) confirmed the boundary coating structure of the hydrothermal precursor and provided insights into the phase structure of the nanometer-sized zirconium carbide. The reaction mechanism and temperature involved in the carbothermic reaction process were determined through calculations. Furthermore, the energy, phase and microstructure of the reaction were investigated using Thermogravimetric Analysis (TG-DSC) and X-ray Diffraction (XRD) at different temperatures. The obtained results revealed that the zirconium carbide precursor was synthesized via the hydrothermal method exhibited a core-shell structure with a boundary coating, which not only ensured uniform contact between C and ZrO2 particles but also facilitated the formation of zirconium carbide. The results show that the most suitable process parameters are Zr/C 1: 7, 240 °C and 24 h. The thermodynamic calculation results show that ZrO2 combines with carbon to form CO and ZrC when the temperature reaches 1656.56 °C. As the temperature rises, CO reacts with ZrO2 to form ZrC and CO2. TG-DSC shows that the carbothermal reduction reaction starts at 1100 °C and reaches its peak at 1418 °C. XRD analysis confirms that when the temperature reached 1450 °C ZrC appeared. At 1600 °C, the phase transition of ZrC is basically completed. TEM images showed that the synthesized zirconium carbide particles were about 30 nm.

Aluminium-assisted in situ synthesis of bulk SiC nanowhiskers-alumina ceramics using waste coal gangue with high carbon

The green and efficient use of coal gangue (CG) is urgently required in the Chinese coal industry to avoid its adverse environmental impact. This study proposed an Al-assisted carbothermal reduction method to synthesise SiC–Al2O3 ceramics using high-C CG. The optimised experimental conditions for sintering SiC and their effects on the phase composition and related properties of the composites were investigated. The addition of Al optimised the in-situ synthesis pathway of SiC and significantly improved the carbothermal reaction efficiency, making the reactive temperature decrease from 1500 to 1200 °C. Additionally, sintering temperatures could modulate the SiC morphology by affecting the generation of SiO (gas) and the liquid phase of melting Al. The H3 formulation sintered at 900 °C was appropriate for producing SiCw/Al2O3 ceramics with a bending strength of 49.24 MPa, a thermal conductivity of 1.720 W (m K)−1 and good thermal shock resistance (no cracks forming after 20 cycles). This study aimed to fully combine the reactivity changes of CG with the melting reduction reaction of Al. Findings in this work offer novel insights into the synthesis of structural ceramics and the cleaner use of CG for solar thermal storage.

Dual-Schottky-junctions coupling device based on ultra-long β-Ga2O3 single-crystal nanobelt and its photoelectric properties

High quality β-Ga2O3 single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132 μm were synthesized by carbothermal reduction method. Based on the grown nanobelt with the length of 600 μm, the dual-Schottky-junctions coupling device (DSCD) was fabricated. Due to the electrically floating Ga2O3 nanobelt region coupling with the double Schottky-junctions, the current I S2 increases firstly and rapidly reaches into saturation as increase the voltage V S2. The saturation current is about 10 pA, which is two orders of magnitude lower than that of a single Schottky-junction. In the case of solar-blind ultraviolet (UV) light irradiation, the photogenerated electrons further aggravate the coupling physical mechanism in device. I S2 increases as the intensity of UV light increases. Under the UV light of 1820 μW/cm2, I S2 quickly enters the saturation state. At V S2 = 10 V, photo-to-dark current ratio (PDCR) of the device reaches more than 104, the external quantum efficiency (EQE) is 1.6 × 103%, and the detectivity (D*) is 7.5 × 1012 Jones. In addition, the device has a very short rise and decay times of 25−54 ms under different positive and negative bias. DSCD shows unique electrical and optical control characteristics, which will open a new way for the application of nanobelt-based devices.