Formation Of Phase Research Articles

Complex charge density waves in simple electronic systems of two-dimensional III2–VI3 materials

AbstractCharge density wave (CDW) is the phenomenon of a material that undergoes a spontaneous lattice distortion and modulation of the electron density. Typically, the formation of CDW is attributed to Fermi surface nesting or electron-phonon coupling, where the CDW vector (QCDW) corresponds to localized extreme points of electronic susceptibility or imaginary phonon frequencies. Here, we propose a new family of multiple CDW orders, including chiral Star-of-David configuration in nine 2D III2–VI3 van der Waals materials, backed by first-principles calculations. The distinct feature of this system is the presence of large and flat imaginary frequencies in the optical phonon branch across the Brillouin zone, which facilitates the formation of the diverse CDW phases. The electronic structures of 2D III2–VI3 materials are relatively simple, with only III-s,p and VI-p orbitals contributing to the formation of the CDW order. Despite that, the CDW transitions involve both metal-to-insulator and insulator-to-insulator transitions, accompanied by a significant increase in the bandgap caused by an enhanced electronic localization. Our study not only reveals a new dimension in the family of 2D CDWs, but is also expected to offer deeper insights into the origins of the CDWs.

Biosynthesis; Characterization; and Antibacterial, Antioxidant, and Docking Potentials of Doped Silver Nanoparticles Synthesized from Pine Needle Leaf Extract

The current study focused on the synthesis of doped silver nanoparticles (doped AgNPs) with yttrium (Y), gadolinium (Gd), and chromium (Cr) from pine needle leaf extract (PNLE). X-ray diffraction (XRD) was performed to assess the phase formation, detecting 61.83% from Ag and 38.17% for secondary phases of AgCl, AgO, Y, Cr-, and Gd phases. The size and shape of the NPs were determined by transmission electron microscopy (TEM), showing a spherical shape with an average particle size of 26.43 nm. X-ray photoelectron spectroscopy (XPS) detected the oxidation state of the presented elements. The scanning electron microscope (SEM) and the energy-dispersive X-ray analysis (EDX) determined the morphology and elemental composition of the NPs, respectively. Fourier transform infrared spectroscopy (FTIR) determined the different functional groups indicating the presence of Ag, Y, Gd, Cr, and other groups. Photoluminescence (PL) spectroscopy showed the optical properties of the NPs. A vibrating sample magnetometer (VSM) revealed the ferromagnetic behavior of the doped AgNPs. The antibacterial activity of the doped AgNPs was tested against six uro-pathogenic bacteria (Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) microdilution assays, agar well diffusion assay, time–kill test, and antibiofilm screening assays, revealing significant activity, with MICs ranging between 0.0625 and 0.5 mg/mL and antibiofilm activity between 40 and 85%. The antioxidant activity was determined by the 1,1, diphenyl 1-2 picrylhydrazyl (DPPH) radical scavenging assay with a potential of 61.3%. The docking studies showed that the doped AgNPs had the potential to predict the inhibition of crucial enzymes such as penicillin-binding proteins, LasR-binding proteins, carbapenemase, DNA gyrase, and dihydropteroate synthase. The results suggest that the doped AgNPs can be applied in different medical domains.

Phase Formation Behavior and Thermoelectric Transport Properties of Solid Solution Composition Between SnTe and InTe

Phase Formation Behavior and Thermoelectric Transport Properties of Solid Solution Composition Between SnTe and InTe

Multi-step thermal design of microwave vacuum heating to basaltic regolith simulant towards lunar base construction.

Humanned exploration and extended stay on the Moon are the hottest challenges today. We report highly robust materials by microwave heating under high-vacuum conditions (10- 3 Pa) from a basaltic regolith simulant (FJS-1) to ensure the feasibility of lunar infrastructure construction. The violent degassing dynamics were revealed by monitoring vacuum pressure during heating and analyzing the compounds evolved from basaltic silicate compounds: thermal pyrolysis of silicate compounds became more pronounced above 1000 oC, leading to a catastrophic deformation accompanied by forming countless pores of several hundred µm sizes. The preferential formation of the magnetite phase in vacuum heating dominantly caused the radical change in microwave absorption capacity compared with conventional heating routes using an electrical furnace in atmospheric conditions. Besides, the in-situ measurement of dielectric properties during microwave vacuum heating clarified the increase in one order of magnitude from 100 to 1000 oC. Based on the presumed phenomena during microwave-vacuum heating for basaltic regolith, we propose a new thermal design concept to overcome the practical limitations of microwave technology. The multi-step temperature profile successfully fabricated a highly robust product that demonstrated world-class mechanical performance, equivalent to the compressive strength of 65MPa without any vigorous hydrostatic cold press as a pre-treatment.

Facile synthesis and characterization of zinc molybdate (ZnMoO4) nanosheets for electrochemical supercapacitor application

Abstract This study explores the synthesis and characterization of zinc molybdate (ZnMoO4) nanosheets with emphasis on their potential application for energy storage devices particularly supercapacitors. The synthesis of ZnMoO4 nanosheets was done through co-precipitation followed by examination of their structure, morphology, optical, thermal behaviour and electrochemical performance by various characterization techniques. X-ray diffraction (XRD) analysis confirmed that the formation of monoclinic ZnMoO4 phase with the average crystallite size 17.93 nm. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) revealed that this material had nanosheets-like structure which helps to increase ion transport and surface area; these two factors are essential for enhancing the material’s supercapacitor efficacy. The semiconductor characteristics were determined using UV–Visible diffuse reflectance spectroscopy (UV-DRS) which indicated a band gap energy of 4.2 eV. Fourier transform infrared (FTIR) analysis confirmed that the presence of Zn–O and Mo–O bonds in their crystal lattice. Thermogravimetric analysis (TGA) showed that the ZnMoO4 nanosheets had thermal stability since they experienced only a slight mass loss of 2.57 % up to 800 °C. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were undertaken to find out the specific capacitance and the value is 618 F g⁻1 at a current density of 1 A g⁻1.

SYNTHESIS AND CHARACTERIZATION OF ZEOLITES FROM COAL FLY ASH WASTE

South Sumatra had coal production through PT Bukit Asam Tbk, which had coal production since 1950. Tanjung Enim Steam Power Plant (PLTU) is the largest coal ash producer because coal is the primary fuel. Coal combustion by-products include coal fly ash (CFA) and coal bottom ash (CBA). The current utilization of the CFA Tanjung Enim Steam Power Plant is for a cement mixture of PT Semen Baturaja and planting media. This work attempts to optimize zeolite synthesis from CFA by examining the effects of hydrothermal duration on reducing coal waste. This research studies the effect of hydrothermal time with time variations of 5, 12, and 24 on the morphology and phase of zeolite obtained. CFA from the Tanjung Enim Steam Power Plant contains SiO₂ and Al₂O₃, which account for 47.7% and 28.7% of the total composition, respectively. The SEM characterization result shows that the synthesized zeolite forms aggregates with a particle size of about 8-15 μm. Based on XRD characterization of CFA hydrothermal time of 5 hours, the dominant phase is the gibbsite phase, but there is a sodalite phase. The 12-hour hydrothermal time showed the formation of quartz, gibbsite, and sodalite phases. The 24-hour hydrothermal time shows that the dominant phase is sodalite, but there are gibbsite and quartz phases. The peak of the quartz phase decreases the longer the hydrothermal time. In this study, the duration of the hydrothermal process affects the formation of the zeolite phase.

Proton-exchange induced reactivity in layered oxides for lithium-ion batteries.

LiNixCoyMn1-x-yO2 (0 < x, y < 1, NCM) is the dominant positive material for the state-of-the-art lithium-ion batteries. However, the sensitivity of NCM materials to moisture makes their manufacturing, storage, transportation, electrode processing and recycling complicated. Although it is recognized that protons play a critical role in their structure stability and performance, proton exchange with Li+ in NCM materials has not been well understood. Here, we employ advanced characterizations and computational studies to elucidate how protons intercalate into the layered structure of NCM, leading to the leaching of Li+ and the formation of protonated NCM. It is found that protonation facilitates cation rearrangement and formation of impurity phases in NCM, significantly deteriorating structural stability. The adverse effects induced by protons become increasingly pronounced with a higher Ni content in NCM. Through a comprehensive investigation into the thermodynamics and kinetics of protonation, we discover that Li deficiencies in NCM materials can be resolved via solution process in the presence of Li+ ions and controlled proton concentration. The underlying mechanism of relithiation is further explored through materials characterizations and kinetics modeling. This work provides crucial insights into controlling structural and compositional defects of Li-ion battery positive material in complicated processing environment.

Properties of Al0.5CoCrFeNi2Ti High-Entropy Alloy System: From Gas-Atomized Powders to Atmospheric Plasma-Sprayed Coatings

AbstractThe performance of the Al0.5CoCrFeNi2Ti HEA atmospheric plasma-sprayed coating was extended from characterizing the properties of its powder prepared via the gas atomization method. It was observed that the gas-atomized HEA powders possessed a solid solution BCC phase, while a major phase transformation to a FCC-L21 intermetallic phase occurred during the annealing process. The formation of the intermetallic phase resulted in an increase in average hardness from 6.28 to 7.64 GPa after annealing at 900 °C for 1 h. Afterward, HEA powders were applied in the atmospheric plasma spray technology. The phase constitution of Al0.5CoCrFeNi2Ti HEA coatings was investigated by varying powder size and applied current. It was observed that the smaller powder sizes prone to oxidation, whereas higher applied current facilitated the phase transformation from BCC to FCC phase. The nanoindentation test indicated distinct average microhardness values for the interlamellar oxide region, BCC unmelted particle and FCC phase lamellar region, which was measured at 12.35, 8.68 and 5.97 GPa, respectively. As a result, the adjustability of coating hardness was achieved by manipulating the relative phase ratio.

Non‐Destructive and Mechanical Characterization of the Bond Quality of Co‐Extruded Titanium‐Aluminum Profiles

The transportation industry aims to improve energy efficiency and reduce CO2 emissions, with a focus on reducing vehicle mass. A key method involves advanced lightweight construction techniques using materials like aluminum alloys. Research is concentrated on developing processes to combine different materials into reinforced hybrid components, such as aluminum and titanium. This study focuses on the lateral angular co‐extrusion (LACE) process to produce hybrid hollow profiles of EN AW‐6082 and Ti6Al4V, investigating the impact of the thermomechanical processing during extrusion and heat treatment (HT) on the resulting bond quality and material properties. Various HT routes are tested to see their impact on intermetallic phase formation, longitudinal weld seams, and bonding strength. Mechanical testing evaluates the tensile strength of the joining zone, while nondestructive ultrasonic testing (UT) assesses joining zone integrity and poor bonding detection. Results indicate that HT parameters significantly influence the bond quality and mechanical properties of hybrid profiles. UT data shows a strong correlation with tensile strength and intermetallic phase growth, providing a nondestructive way to evaluate bond quality. This study highlights the potential of LACE processes and optimized HT strategies to improve the performance and reliability of aluminum–titanium hybrid components.

Effect of annealing conditions on resistive switching in hafnium oxide-based MIM devices for low-power RRAM

Abstract This work presents resistive switching (RS) behaviour in HfO2-based low-power resistive random-access memory (RRAM) devices. A metal-insulator-metal (MIM) structure (Au/HfO2/Pt) was fabricated by sandwiching a thin insulating layer of HfO2 between Pt and Au electrodes. HfO2 films deposited by RF sputtering at room temperature were rapid thermally annealed in N2 ambient at 400 °C and 500 °C. Grazing angle x-ray diffraction (GIXRD), Field emission gun-scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) were employed to analyse the phase, crystal structure, morphology, surface roughness and chemical composition of the HfO2 films. The bipolar RS could be observed in both as-deposited and annealed HfO2 film-based devices from I–V characteristics measured using a source meter. We have investigated the effect of annealing temperature and annealing ambient on the phase formation of HfO2 as well as the RS characteristics and compared with as-deposited film-based device. Annealed HfO2 film-based devices exhibited improved electrical characteristics, including stable and repeatable RS at significantly lower switching voltages (&lt;1 V) which indicates low power consumption in these devices. The relatively lower processing temperature of the HfO2 films and that too in the films deposited by physical vapor deposition (PVD) technique-RF magnetron sputtering makes this study significantly useful for resistive switching based non-volatile memories.

In situ phase engineering during additive manufacturing enables high-performance soft-magnetic medium-entropy alloys.

Additive manufacturing (AM) shows promise as a method for producing soft-magnetic multicomponent alloys for use in electric motors and sustainable electromobility applications. However, the simultaneous achievement of a high saturation magnetic flux density (Bs) and a low coercivity (Hc) in AM soft-magnetic materials remains challenging. Herein, we present an approach that integrates an elemental powder mixture of Fe45Co30Ni25 with Fe2O3 nano-oxides, which is then subjected to laser powder bed fusion (LPBF) followed by high-temperature annealing to achieve an FCC-structured Fe45Co30Ni25 MEA/FeO composite. The FeO nanoparticles, a byproduct of the reaction between Fe powders and Fe2O3 nano-oxides, serve as nucleation sites for the formation of a single FCC phase in the MEA matrix. The resulting LPBF MEA/FeO composite has a Bs of 2.05 T and an exceedingly low Hc of 115 A m-1, compared to those of the BCC/FCC dual phase MEA and other state-of-the-art additively manufactured soft-magnetic alloys. In situ Lorentz transmission electron microscope (TEM) revealed that the low Hc of the FCC-structured MEA/FeO composite originates from the reduced pinning effect of grain boundaries in the FCC phase on domain wall movement compared with those in the FCC/BCC dual phase.

Chitosan as a Templating Agent of Calcium Phosphate Crystalline Phases in Biomimetic Mineralization: Theoretical and Experimental Studies.

Highlighting the essential role of chitosan (CS), known for its biocompatibility, biodegradability, and ability to promote cell adhesion and proliferation, this study explores its utility in modulating the biomimetic mineralization of calcium phosphate (CaP). This approach holds promise for developing biomaterials suitable for bone regeneration. However, the interactions between the CS surface and in situ precipitated CaP still require further exploration. In the theoretical section, molecular dynamics (MD) simulations demonstrate that, at an appropriate pH level during the prenucleation stage, calcium ions (Ca2+) and hydrogen phosphate ions (HPO42-) form Posner-like clusters. Additionally, the interaction between these clusters and the CS molecule enhances system stability. Together, these phenomena facilitate the transition to subsequent heterogeneous nucleation on the surface of the organic matrix, which is a more controlled process than homogeneous nucleation in solution. Dynamic simulation results suggest that CS acts as a stabilizing matrix at pH 8.0 during biomimetic mineralization. In the experimental section, the effects of pH and the molecular weight of CS were investigated, with a focus on their impact on the crystal structure of the resulting material. X-ray diffraction and scanning electron microscopy analyses reveal that, under conditions of approximately pH 8.0 and a CS molecular weight of 20 000 g/mol, and controlled ion concentration, ultrasound radiation, and temperature, the dominant CaP phases in the material are carbonate-doped hydroxyapatite (CHA) and octacalcium phosphate (OCP). These findings suggest that CS, when adjusted for molecular weight and pH, facilitates the formation of CaP crystal phases that closely resemble the natural inorganic composition of bone, highlighting its protective and regulatory roles in the growth and maturation of crystals during mineralization. The theoretical predictions and experimental outcomes confirm the crucial role of CS as a templating agent, enabling the development of a biomimetic mineralization pathway. CS's ability to guide this process may prove valuable in the design of materials for bone tissue engineering, particularly in developing effective materials for bone tissue healing and regeneration.

Carbon Nitride‐Supported Zinc Oxide Nanocomposite for the Electrochemical Detection of Dopamine and the Development of Disposable Sensors

AbstractThe carbon nitride‐supported zinc oxide (CNZO) nanocomposite was synthesized through a high‐temperature synthesis method, resulting in zinc oxide nanoparticles with an average size of ~44 nm, dispersed on a carbon nitride matrix. X‐ray diffraction confirmed the formation of the hexagonal wurtzite phase of zinc oxide, with a space group of P63mc. X‐ray photoelectron spectroscopy and Fourier‐transform infrared analysis further verified the presence of both zinc oxide and carbon nitride. The CNZO nanocomposite served as a catalyst for the electrochemical detection of dopamine, achieving limit of detection and sensitivity of 2.66 μM and 6.23 μA μM−1 cm−2 respectively, using square wave voltammetry technique. Cyclic voltammetry experiments demonstrated excellent electroactivity of the CNZO nanocomposite in a neutral pH environment. An electrochemical paper‐based analytical device (EPAD) was designed and successfully employed for the electrochemical analysis of dopamine in pharmaceutical samples using CNZO nanocomposites. Additionally, CNZO was used as an active material in the development of a disposable dopamine sensor based on an extended gate field‐effect transistor (EG‐FET). This sensor exhibited a sensitivity and limit of detection 18.22 μA μM−1 cm−2 and 0.36 μM, respectively, with a correlation coefficient of 0.99.

Preparation and Properties of Fe-Based Double Perovskite Oxide as Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cell

Double perovskite oxides with mixed ionic and electronic conductors (MIECs) have been widely investigated as cathode materials for solid oxide fuel cells (SOFCs). Classical Fe-based double perovskites, due to their inherent low electronic and oxygen ionic conductivity, usually exhibit poor electrocatalytic activity. The existence of various valence states of B-site ions modifies the material’s catalytic activity, indicating the possibility of the partial substitution of Fe by higher-valence ions. LaBaFe2−xMoxO5+δ (x = 0, 0.03, 0.05, 0.07, 0.1, LBFMx) is used as intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode materials. At a doping concentration above 0.1, the Mo substitution enhanced the cell volume, and the lattice expansion caused the formation of the impurity phase, BaMoO4. Compared with the parent material, Mo doping can regulate the oxygen vacancy concentration and accelerate the oxygen reduction reaction process to improve the electrochemical performance, as well as having a suitable coefficient of thermal expansion and excellent electrode stability. LaBaFe1.9Mo0.1O5+δ is a promising cathode material for IT-SOFC, which shows an excellent electrochemical performance, with this being demonstrated by having the lowest polarization resistance value of 0.017 Ω·cm2 at 800 °C, and the peak power density (PPD) of anode-supported single-cell LBFM0.1|CGO|NiO+CGO reaching 599 mW·cm−2.

Spectroscopic Investigation of the Interaction of Silicate Ions with Lead Carbonates Under Drinking Water Conditions.

The presence of lead has been identified as a critical health risk in drinking water systems serviced by Pb-bearing plumbing. Among several corrosion control strategies, the use of sodium silicates has attracted interest due to the advantages it offers compared to other approaches, such as phosphate dosage. However, the interaction of silicate ions with lead corrosion scales and other ubiquitous dissolved species such as Al ions in drinking water is not well understood. In this work, surface and bulk spectroscopic analysis of the solid scale is combined with quantitative analysis of the aqueous phase. A detailed spectroscopic probing of the transformations taking place on the solid phase enables us to develop a mechanistic framework for reports published in the last four years in the open literature, suggesting that silicates may not be an adequate corrosion control option in drinking water systems rich in solid lead carbonates. The spectroscopic data obtained demonstrate that in the presence of chlorine residual, silicates inhibit Pb(II) carbonates from oxidizing into less soluble Pb(IV) oxides thus, negatively impacting water quality. Furthermore, aluminum ions interact with silicates resulting in the formation of solid allophane phase over the lead scale surface, extending into the bulk. However, the formation of this new solid allophane phase does not protect against lead dissolution.

Understanding of a Ni-Rich O3-Layered Cathode for Sodium-Ion Batteries: Synthesis Mechanism and Al-Gradient Doping.

O3-type NaNi0.8Mn0.1Co0.1O2 (NaNMC811) cathode active materials for sodium-ion batteries (SIBs), with a theoretical high specific capacity (∼187mAhg-1), are in the preliminary exploration stage. This study comprehensively investigates NaNMC811 from multiple perspectives. For the first time, the phase evolution ( - - ) during the solid-state synthesis is systemically investigated, which elucidates in-depth the mechanisms of the thermal sodiation process. Furthermore, an Al-gradient doping of NaNMC811 wassuccessfully implemented through Al2O3 coating on the cathode active material (CAM) precursor. The modified Al-NaNi0.8Mn0.1Co0.1O2 (Al-NaNMC811) exhibits excellent electrochemical dynamics and performance, maintaining a specific capacity above 100mAhg-1 after 100 cycles at 0.1 C (1.5-4.1 V) while providing a promising capacity retention of 63%. Additionally, the material demonstrates excellent rate capabilities, retaining a specific capacity of 107 mAh g-1 at 5 C. Compared to pristine NaNMC811, the modified Al-NaNMC811 is proven to have improved electrochemical kinetics with a higher Na+ diffusion coefficient due to dilated (003) interplanar spacing, and a more stable structure during the electrochemical charge-discharge processes, which is attributed to stronger Al-O bond energy. Understanding phase formations during the synthesis and comprehensive insight in the gradient doping for O3-type NaNMC811 CAMs guides further development of next-generation SIBsmaterials.

Enhanced Adsorption and Photocatalytic Activity of Vertically Oriented TiO2 Nanotube Arrays by Li Incorporation

A highly efficient, solid, and easily maneuverable adsorbent and photocatalyst, Li‐incorporated titanate nanotubes that manifest adsorption efficiency of 98.1% and photocatalytic efficiency of 99.6% in 60 min and 97.8% and 98.5%, respectively, in a shorter duration of 20 min, is synthesized by a facile two‐stage electrochemical technique. The modified nanotubes exhibit good cyclic stability of 93.7% photodegradation of malachite green dye after three continuous cycles. The adsorption data show the highest correlation for second‐order pseudo kinetics and Freundlich isotherm, suggesting multilayer chemisorption with an adsorption capacity of kF ≈ 219.51 mg1–1/nL1/ng−1. Fourier transform infrared spectroscopy (FTIR) analysis of the adsorbent before and after the adsorption corroborates the findings. X‐Ray photoelectron spectroscopy reveals the formation of a larger number of oxygen vacancies (Ti3+/Ti2+) that facilitate more carrier release for the production of reactive oxygen species during photocatalysis. X‐Ray diffraction and transmission electron microscopy analysis confirm a secondary rutile phase formation on Li doping that promotes heterogeneous multilayer adsorption. Field‐emission spectroscopic studies reveal a change in the morphology of the doped tubes with porous aggregate formation on the surface. The structural, morphological, and compositional change brought about by Li incorporation facilitates the use of titania nanotubes as an efficient adsorbent cum photocatalyst in the removal of malachite green dye.

Support of the luteal phase in programs for transferring thawed embryos into the uterine cavity in patients with overweight and obesity

Introduction. Progesterone levels are a critical factor for embryo implantation in in vitro fertilization (IVF) programs, including thawed embryo transfer programs. Overweight/obese patients often have lower blood progesterone concentrations in the luteal phase during IVF cycles, which requires an individual approach to planning luteal support in this category of patients.Aim. To compare the pregnancy ratе and miscarriage rates up to 12 weeks of pregnancy in overweight/obese patients who underwent a program of transfer of thawed embryos into the uterine cavity, depending on the type and route of administration of gestagens.Materials and methods. The study included 76 overweight or obese patients. All patients were treated for infertility using a program for transferring a thawed embryo into the uterine cavity; luteal phase support was carried out either using micronized progesterone, identical to natural, – the drug Utrogestan in a daily dose of 800 mg intravaginally (40 patients), or combination therapy was prescribed – vaginal gel with progesterone 90 mg in combination with the synthetic progestin dydrogesterone in a daily dose of 30 mg, taken orally (36 patients).Results. The rates of pregnancy and miscarriage in the first trimester were comparable in both groups and did not depend on differences in luteal support.Conclusions. The formation of the luteal phase of the cycle in patients with overweight/obesity is equally effective using various forms of gestagens. The use of micronized progesterone may be preferable in patients with overweight/obesity in terms of the ability to monitor blood progesterone levels, a more favorable metabolic profile when used vaginally, and the possibility of switching to oral administration of the drug in the event of the development of adverse local events.

Modulator-Directed Counterintuitive Catenation Control for Crafting Highly Porous and Robust Metal-Organic Frameworks with Record High SO2 Uptake Capacity.

Sulfur dioxide (SO2) is an important industrial feedstock that can be directly utilized or catalytically transformed to value-added chemicals such as sulfuric acid. The development of regenerable porous sorbents for the highly efficient storage and energy-minimal release of toxic SO2 operating under ambient conditions has attracted growing interest. Herein, we report the topology-guided construction of highly porous acs-type metal-organic frameworks (MOFs) through a counterintuitive modulator-directed catenation control approach. In contrast to the conventional modulator facilitated coordination competition that favors the thermodynamic catenated phase, we show that the elevation of modulator concentration can promote the formation of the noncatenated phase probably through a sublattice dissolution pathway. The assembly of a custom-designed trigonal prismatic triptycene-quinoxaline linker and trinuclear Fe3O cluster affords either the threefold catenated SJTU-219 or noncatenated SJTU-220 with desired acs net. Impressively, the synthetic approach is applicable to various metal ions, including Al3+, V3+, and even Ti4+. The noncatenated SJTU-220 exhibits an extraordinary SO2 sorption capacity of 29.6 mmol g-1 at 298 K and 1 bar, surpassing all reported solid sorbents. The uptake capacity can be further raised to 35.6 mmol g-1 via the replacement of Fe3+ with kinetically more inert Cr3+, resulting in a staggering ∼329-fold volume reduction compared with free ideal SO2 gas. Computational simulations suggest that unique Fe3+···S(SO2) interactions dominate the SO2 seeding process, facilitating the efficient packing of SO2 molecules in the large channels. Besides, the exceptionally low uptake at the low pressure region implies global weak framework-SO2 interactions, which offer great potential for practically implementing an "easy-on/easy-off" SO2 delivery system.

Impact of low-grade iron ore on sintering reactions: Rapid heating experiments and thermodynamic modeling

BackgroundSinter is a primary feedstock for blast furnace-based ironmaking. Recently, the proportion of low-grade iron ore, which contains a high amount of gangue (mainly SiO2), has been increasing in the sintering process. Therefore, the impact of increased SiO2 content on the quality of sinter needs to be clarified. MethodsIn this study, we designed a rapid-heating furnace to simulate the actual thermal profile of the sintering process. The effects of basicity values, sintering temperature, and atmosphere, on the microstructure and phase formation of the Fe2O3-CaO-SiO2 ternary mixtures during sintering reactions, are investigated using X-ray diffractometry and scanning electron microscopy. The experimental results are analyzed using CALPHAD-type computational thermodynamics. Significant findingsWe found that solid-state reactions dominate at the lower temperature of 1250 °C, while liquid-assisted sintering occurs at the higher temperature (1300 °C). As the SiO2 content in the sinter increases, the content of the calcium-ferrite bonding phase decreases, while the content of Ca2SiO4 and Fe2O3 increases. Regarding the role of the atmosphere, more calcium ferrite bonding phases form under a lower oxygen partial pressure compared to an ambient atmosphere, which facilitates the densification of the Fe2O3-CaO-SiO2 sinter. In addition, a guideline for sintering operation with low-grade iron ore is proposed.