Fe2O3 Powders Research Articles

Preparation of magnetothermal Fe3O4/MgO/HA composite scaffolds for cancer hyperthermia by Vat Photopolymerization

Bone defects resulting from bone tumor resections are often complicated with residual cancer cells. To address the challenge, the magnetothermal porous structured bone scaffolds of hydroxyapatite-Fe3O4-MgO (HA-FM) were fabricated by Vat Photopolymerization (VPP). This study improved curing behavior by doping Mg(OH)2 into Fe3O4 powder via the chemical deposition method. Mg(OH)2 functioned as a pore-forming agent during the sintering process, decomposing into MgO to enhance biocompatibility. A two-step debinding method combined with a carbon powder embedding sintering process was used employed to resolve the conflict between the removal of photosensitive resin and the oxidation of Fe3O4. After sintering at 1200°C, the porosity of the composite ceramics reached 69% and a compressive strength of 2.28MPa. In vitro mineralization tests showed that doping with Fe3O4 and Mg(OH)2 could promote the scaffolds’ degradation in simulated body fluid (SBF), beneficial to mineralization process. In vitro cell proliferation and adhesion experiments showed that ceramic samples were not cytotoxic and could promote osteogenic differentiation. The composite scaffolds exhibited magnetothermal properties, achieving a temperature increase of 8.2°C in the alternating magnetic field of 92G and 100kHz, indicating potential for cancer treatment.

Flexible Terahertz Broadband Absorber Based on a Copper Composite Film.

Terahertz absorbers play a crucial role in terahertz detectors, radar stealth, electromagnetic shielding, and other fields. However, the design and fabrication of flexible terahertz broadband absorbers remain a challenge at present. Here, we demonstrated a terahertz broadband absorber based on a copper composite film (CCF) consisting of a copper foam and an organic silica gel doped with Fe3O4 powder. The CCF can be fabricated by the infiltration method. The influence of the thickness and the pore size of the copper foam and the mass fraction of doped Fe3O4 powder on the absorption bandwidth were investigated. When the thickness of the CCF is 1.5 mm, the pore size of the copper foam is 95 pores per inch (ppi), and the mass fraction of Fe3O4 is 1%; a broadband absorption is achieved in the range of 0.11-3.5 THz. It is noted that the mass fraction of Fe3O4 has a significant impact on the absorption bandwidth. In addition, the thickness of the CCF and the pore size of the copper foam also have an impact on the absorption. The impedance matching theory is introduced to understand the mechanism of broadband absorption. This flexible broadband absorber has potential application in terahertz stealth, shielding, and the sixth-generation (6G) broadband wireless communication in the future.

Crystal Structures and Piezoelectric Properties of Quenched and Slowly-Cooled BiFeO3-BaTiO3 Ceramics.

The BiFeO3-BaTiO3 (BF-BT) ceramics were here prepared through the solid-state reaction of Bi2O3, Fe2O3 and nano-sized BT powders. The crystal structures and piezoelectric properties were investigated in both quenched (AQ) and slowly cooled (SC) 0.7BF-0.3BT ceramics. Prior work has shown that rhombohedral and pseudo-cubic phases coexist in 0.7BF-0.3BT ceramics. In this work, the crystal structure of the pseudo-cubic phase was refined as a non-polar orthorhombic Pbnm phase in the SC sample and as a polar orthorhombic Pmc21 phase in the AQ sample. In addition to a sharp dielectric peak at about 620 °C, corresponding to the Curie temperature of the rhombohedral phase, a broad dielectric peak with strong frequency dispersion and a sharp frequency-independent dielectric peak were observed at around 500 °C in the SC and AQ samples, respectively. We determine that the dielectric anomalies around 500 °C were caused by a relaxor phase transition of the non-polar orthorhombic phase in the SC sample and a ferroelectric-paraelectric phase transition of the polar orthorhombic phase in the AQ sample. The AQ sample showed better ferroelectric and piezoelectric properties than the SC sample. The 0.7BF-0.3BT ceramic slowly cooled in a nitrogen atmosphere showed a well-saturated P-E curve and a similar temperature-dependent dielectric constant as the AQ sample. Our results indicate that large concentrations of oxygen vacancies produce a more distorted polar orthorhombic phase and better piezoelectric properties in the AQ sample than in the SC sample.

Ball milling and annealing effect in structural and magnetic properties of copper ferrite by ceramic synthesis

This study aims to better understand the relationship between the microstructure and magnetic properties of copper ferrite, which is an inverse spinel that present a body-centered tetragonal structure associated with a remarkable Jahn–Teller (JT) effect. For this goal, a sample has been synthesized by the ceramic route from a stoichiometric mixture of high-purity CuO and Fe2O3 powders activated mechanically in a high-energy planetary ball mill. This sample was calcined in air furnace at 1000 ºC for 6 h. As synthetized sample with a cubic structure was divided into two parts and one of them was annealed at 650 ºC for 3 h and slowly cooled to room temperature to obtain a pure tetragonal spinel sample. Furthermore, these two samples were subjected to the same processes of severe plastic deformation by milling for up to 70 h and subsequent annealing at temperatures ranging between 300 and 600 ºC to obtain samples with a mixture of phases in different proportions. For the cubic one, there is no change in its structure due to milling, always remaining 100 % cubic, and the evolution in the saturation magnetization was related to the changes in the density of defects present. On the other hand, copper cations are always found in the octahedral sites of spinel with a tetragonal structure. The small decrease in the degree of inversion to 0.95 induced by milling in this sample is capable of breaking the JT distortion, giving rise to the appearance of a cubic phase. This work demonstrates how the structure, microstructure, defects like stacking faults and deformation twins, and degree of inversion of the different phases are related to changes in magnetic properties.

The effects of raw materials particle sizes on the solid-state reaction progress, morphology and magnetic properties of M-type strontium hexaferrites

In this work, the effects of SrCO3 and Fe2O3 particle size on the reaction process, morphology and magnetic properties of M-type strontium hexaferrites (SrM) have been further studied. Pure strontium hexaferrite magnetic sample based on SrCO3 and Fe2O3 molar ratio of 1:6 has been successfully prepared at 1150 °C. The results indicated that Fe2O3 particle size was the main factor of affecting the formation of SrM, a pure SrM phase magnetic sample was able to obtain at lower calcination temperatures by using fine Fe2O3 powder as raw material, and at the same calcination temperature, a sample using fine Fe2O3 powder as raw material was able to obtain pure SrM phase magnetic sample with shorter holding time. When the mean particle size of Fe2O3 was below 60 nm, a pure SrM phase magnetic sample was able to form at 1150 °C at a molar ratio of 1:6 of SrCO3 and Fe2O3. In this case, the magnetic parameters of the sample with the optimum magnetic parameters were saturation magnetization MS = 77.8 emu/g and coercive force HC = 4122 Oe. And the solid-state reaction process of the corresponding samples was slightly faster when the mean particle size ratio of Fe2O3 and SrCO3 was between 0.35 and 0.36. Assuming that a SrCO3 particle is surrounded by Fe2O3 particles, it can be inferred that the corresponding molar ratio of Fe and Sr of the nearest raw material particles is between 3.6 and 3.8.

Research on the diffusion plugging mechanism of flowing water grouting slurry in karst pipelines

Among the many adverse geological disasters, the surge water disaster in karst areas causes the greatest loss to underground engineering construction, so it is necessary to carry out relevant research on the management of surge water disaster in karst pipelines. This study presents the creation of an oily epoxy resin magnetic convergence grouting material (OEMS) specifically developed to prevent water infiltration in pipelines. A self-designed visual karst pipeline grouting simulation system was used to conduct an experimental study on the diffusion and plugging behavior of magnetic slurry grouting. A model was constructed to simulate the migration of a magnetic slurry in water inrush circumstances. The model is based on the theory of slurry diffusion and the concept of magnetic adsorption. The results suggest that:(i) The best performance in grouting sealing is achieved when the ratio of new OEMS epoxy resin A liquid to B liquid is 2:1, and the blending ratio of flyash and Fe3O4 powder falls between 25 and 55%. (ii) The primary and secondary correlations among the parameters that affect the rate of change in flow rate, plugging pressure, and slurry retention rate are as follows: Hydrodynamic velocity has the greatest correlation, followed by plugging length, Fe3O4 power ratio, and flyash mixture ratio. (iii) The validity of the model is verified by comparing empirical observations with calculated theoretical values.

Corrosion-induced changes in bio-oil aging: A gas chromatography exploration

Understanding the interactions between metals, corrosion products, and bio-oil (BO) is crucial for safe and efficient BO operations. This study explored BO aging and BO + steel (carbon steel (CS) and stainless steel (SS)) immersion at 80 °C for 168 h, alongside experiments adding synthetic Fe2O3 and Cr2O3 powders to BO. Gas generated was analyzed via gas chromatography (GC). Results showed 80 °C was an optimal pre-heating temperature for BO without gas evolution. BO aging at up to 220 °C for 24 h increased CO2 and CO evolutions. CS immersion at 80 °C produced more H2 and CO2 than those at 50 °C, due to higher corrosion rates. The BO + Fe2O3 trial released less H2 but more CO2 compared to BO + CS immersion, due to internal BO reactions catalyzed by Fe2O3. BO + SS304L and BO + Cr2O3 trials showed similar H2 and CO2 production, highlighting the catalytic effect of Cr2O3. Leached Fe ions in BO formed chelate complexes with organic compounds, causing phase separation. These findings have significant implications for producing renewable biofuels via BO co-processing operations by emphasizing the need to optimize preheating temperatures, validate the compatibility of construction materials, and implement safety measures to mitigate gas accumulation risks.

Enhanced synthesis of sponge-type multiwalled carbon nanotubes using SiO2-Fe2O3 catalysts via aerosol-assisted chemical vapor deposition: Electrochemical and absorption capacity studies

Carbon nanotube sponges synthesized at the laboratory scale typically use a Fe-based organometallic catalyst, but low-cost alternatives with a higher yield ratio are needed for large-scale production. This work introduces a catalyst made from a mixture of silicon dioxide (SiO2) and hematite (Fe2O3) as an innovative alternative for the high-yield production of spongy-type multi-walled carbon nanotubes (ST-MWCNTs). We used a ball-milled mixture of SiO2 and Fe2O3 powders as the catalyst and toluene and N, N-dimethylformamide as carbon and nitrogen sources in an aerosol-assisted catalytic chemical vapor deposition system. Incorporating SiO2 into the Fe-based catalyst increased production yield to 184 % of the catalyst weight. The synthesized ST-MWCNTs exhibited a high crystallinity ratio (ID/IG = 0.34) with a unique entangled bundle-type nanotube configuration. At the same time, the presence of Si atoms and oxygen-type functionalities, demonstrated by X-ray photoelectron spectroscopy, modified their electrochemical behavior, making them suitable for supercapacitor or sensor applications. Additionally, the spongy structure demonstrated a reversible absorption capacity of over 15 times its weight with organic solvents like gasoline or ethylene glycol. This new catalyst configuration opens alternatives for generating higher amounts of 3D carbon nanomaterials with potential energy storage, water filtration, and environmental remediation applications.

Evaluation and Analysis of Cement Raw Meal Homogenization Characteristics Based on Simulated Equipment Models.

In recent years, the variability in the composition of cement raw materials has increasingly impacted the quality of cement products. However, there has been relatively little research on the homogenization effects of equipment in the cement production process. Existing studies mainly focus on the primary functions of equipment, such as the grinding efficiency of ball mills, the thermal decomposition in cyclone preheaters, and the thermal decomposition in rotary kilns. This study selected four typical pieces of equipment with significant homogenization functions for an in-depth investigation: ball mills, pneumatic homogenizing silos, cyclone preheaters, and rotary kilns. To assess the homogenization efficacy of each apparatus, scaled-down models of these devices were constructed and subjected to simulated experiments. To improve experimental efficiency and realistically simulate actual production conditions in a laboratory setting, this study used the uniformity of the electrical capacitance of mixed powders instead of compositional uniformity to analyze homogenization effects. The test material in the experiment consisted of a mixture of raw meal from a cement factory with a high dielectric constant and Fe3O4 powder. The parallel plate capacitance method was employed to ascertain the capacitance value of the mixed powder prior to and subsequent to treatment by each equipment model. The fluctuation of the input and output curves was analyzed, and the standard deviation (S), coefficient of variation (R), and homogenization multiplier (H) were calculated in order to evaluate the homogenization effect of each equipment model on the raw meal. The findings of the study indicated that the pneumatic homogenizer exhibited an exemplary homogenization effect, followed by the ball mill. For the ball mill, a higher proportion of small balls in the gradation can significantly enhance the homogenization effect without considering the grinding efficiency. The five-stage cyclone preheater also has a better homogenization effect, while the rotary kiln has a less significant homogenization effect on raw meal. Finally, the raw meal processed by each equipment model was used for clinker calcination and the preparation of cement mortar samples. After curing for three days, the compressive and flexural strengths of the samples were tested, thereby indirectly verifying the homogenization effect of each equipment model on the raw meal. This study helps to understand the homogenization process of raw materials by equipment in cement production and provides certain reference and data support for equipment selection, operation optimization, and quality control in the cement production process.

Optically detected magnetic resonance study of thermal effects due to absorbing environment around nitrogen-vacancy-nanodiamond powders

We implanted Fe+ ions in nanodiamond (ND) powder containing negatively charged nitrogen-vacancy (NV−) centers and studied their Raman spectra and optically detected magnetic resonance (ODMR) in various applied magnetic fields with green light (532 nm) excitation. In Raman spectra, we observed a blue shift of the NV− peak associated with the conversion of the electronic sp3 configuration to the disordered sp2 one typical for the carbon/graphite structure. In the ODMR spectra, we observed a red shift of the resonance position caused by local heating by an absorptive environment that recovers after annealing. To reveal the red shift mechanism in ODMR, we created a controlled absorptive environment around ND by adding iron-based Fe2O3 and graphitic sp2 powders to the ND suspension. This admixture caused a substantial increase in the observed shift proportional to the applied laser power, corresponding to an increase in the local temperature by 150–180 K. This surprisingly large shift is absent in non-irradiated NV-ND powders, is associated only with the modification of the local temperature by the absorptive environment of NV-NDs, and can be studied using ODMR signals of NV−.

Oxygen exchange in MIEC perovskite-like oxide La0.6Sr0.4Fe0.965Ta0.035O3-δ: Kinetics and equilibrium parameters

Previously, a strategy for doping MIEC perovskites ABO3-δ with highly charged cations B5+ (Nb, Ta) and B6+ (Mo, W) was developed. The doping strategy is based on the idea that strontium ferrite/cobaltite-based perovskites are ferroelastic, whereas highly charged cations are ferroactive species. An increase in the concentration of the dopant leads to a reduction in the size of the domains of the ferroelastic phase down to the nanoscale. This resulted in the smearing of phase transitions with the formation of the highly conductive glassy state. Tantalum-doped lanthanum-strontium-ferrite perovskite (La0.6Sr0.4Fe1-xTaxO3-δ, LSFTx) was prepared via solid-state reaction using chemically pure oxide powders of La2O3, SrCO3, Fe2O3, and Ta2O5, followed by calcination and sintering up to 1350 °C. The structural and surface properties were examined using X-ray diffraction and a scanning electron microscope. The original oxygen partial pressure relaxation (OPPR) method was used to study the kinetic properties of LSFTx. Continuous equilibrium phase diagram “T – pO2 – δ” first obtained by oxygen release technique for composition LSFT3.5. Power law dependencies of the kinetic properties on the oxygen partial pressure are presented.

Biological denitrification performance of a novel sulfur-slow-release carbon source mixed filler

Long-term operation of the sulfur autotrophic denitrification (SAD) process leads to pH reduction, nitrite accumulation, a low nitrogen removal efficiency and excessive sulfate in the effluent. Two slow-release carbon source (SRC) fillers (reactors S2 and S3) consisting of different ratios of hydroxypropyl methyl cellulose, disodium fumarate, polyhydroxy fatty acid ester and Fe3O4 powder were designed to couple SAD with heterotrophic denitrification by using SRC and sulfur particles (reactor S1) as components, combining the advantages of both processes while avoiding secondary pollution. During reactor operation, S3 showed the best denitrification performance. Under the optimal hydraulic retention time of 4 h, different influent nitrate concentrations of 39.92 ± 0.59 mg/L and 20.22 ± 0.45 mg/L achieved average nitrate removal efficiencies up to 88.01 ± 3.62 % and 94.28 ± 2.52 %, and the average denitrification strength were 8.78 mg N/(L·h) and 4.77 mg N/(L·h), respectively. 16S rRNA gene analysis at the genus level showed that the coupled reaction had the highest relative abundance of Thiobacillus associated with SAD, and SAD dominated the coupled system.

Dielectric and Magnetoelectric Properties of TGS-Magnetite Composite.

In our studies, we combined two powdered materials, i.e., ferroelectric triglycine sulfate (TGS) and ferrimagnetic magnetite Fe3O4, to obtain a magnetoelectric composite. The ferroelectric (E) part, i.e., TGS, was a hybrid organic-inorganic crystal, which we obtained as a pure single crystal from an aqueous solution using a static water evaporation method. The magnetic (M) part of the composite was commercially available magnetite. The samples used for the dielectric and magnetoelectric measurements were cold-pressed and made in the form of a circular tablet. The measuring electrodes were made of silver-based conductive paste and were attached to the sample. We measured the temperature dependencies of selected electrical parameters (e.g., dielectric permittivity, electrical capacity, and loss angle tangent). We used the dynamic lock-in method to check whether magnetoelectric coupling existed between the E and M phases. In this paper, we present the dielectric properties of pure monocrystalline TGS as a reference sample and compare the results for TGS powder, TGS + carbon powder, and TGS + Fe3O4 powder. The magnetoelectric coupling presumably appeared for the composite TGS + 10 wt. % Fe3O4, as evidenced by the shift in the phase transition temperature in the TGS. Moreover, the theoretical interpretation of the effect is proposed.

Studies on magnetorheological properties of carbonyl iron/Fe3O4 powder based soft-magnetic fluids with artificial intelligence for industrial applications

For mechanical devices such as haptic gadgets, mechanical dampers, and brake systems to function properly, magnetorheological fluids (MRF)—also known as smart fluids—are crucial. An innovative method for optimizing the preparation process of magnetorheological fluid that is both cost-effective and data-driven in nature is investigated in this article. In this MRF preparation experiment, silicone oil is the carrier liquid and carbonyl iron and Fe3O4 powders are carefully selected as magnetic particles to prepare soft magnetic fluids. Sodium dodecyl benzene sulfonate, oleic acid, polyethylene glycol, graphite, and diatomite were added to improve the MRF's physical qualities. Then, the MRF properties were examined with artificial intelligence method and an enhanced grey wolf optimization algorithm is developed for improving the hyperparameters of the least square support vector machine. In addition, a new procedure for updating individual positions is suggested to better preserve population variety and increase solution quality, and a better updating technique is created for the convergence coefficient vector to avoid local optima. The results show that the suggested modified least square support vector machine is the best algorithm to predict the MRF properties.

Resource utilization of semi-dry flue gas desulfurization ash by thermal treatment on sintering machine

Semi-dry flue gas desulfurization ash (SFGDA) is an abandoned Ca and S resource that is currently stacked without appropriate disposal methods. A technology with industrialization potential, SFGDA, and iron ore thermal processing is an effective approach to obtaining calcium ferrite and industrial sulfuric acid. This study investigated the thermochemical reaction mechanism of SFGDA during high-efficiency pyrolysis employing Fe2O3 and coke powder for self-heating. The results showed that the addition of coke powder enhanced the thermal efficiency and reduced the decomposition temperature, while the reaction is accelerated by the lightning-fast combination of Fe2O3 with the CaO produced during pyrolysis to generate calcium ferrite products. The optimal conditions were determined to be a coke powder dosage of 10% and Fe2O3 dosage of 50%. In semi-industrial experiments, the SFGDA achieved a desulfurization rate of 99% and a calcium ferrite content of 85%. The calcined product CaO from CaSO4 and CaSO3 in the form of calcium ferrite products, with a minimal amount of CaSO4. In addition, during the high-temperature calcination process performed by the sintering machine, the majority of the sulfur within the raw materials migrates as SO2 and is subsequently emitted into the flue gas. Following, this SO2 is captured and utilized for the production of commercially valuable sulfuric acid. When the yield of enabled to calcined product corresponds to 1 ton, it could potentially dispose of 882 kg of SFGDA, culminating in a high-value, harmless, and large-scale SFGDA treatment in steel industry.

On the formation of dendritic iron from alkaline electrochemical reduction of iron oxide prepared for metal fuel applications

Low-temperature electrochemical reduction (electroreduction) of iron oxides is a promising alternative to the conventional methods for iron production due to its CO2-free operation and relatively low energy consumption. In this work, we demonstrate a novel approach for electrochemical iron production by promoting the formation of dendritic structures during iron electrodeposition, which facilitates the easy harvesting of deposits in powder form. Experiments were conducted using a single pair of parallel plate electrodes, immersed in a mixture of hematite (Fe2O3) powder and aqueous alkaline (NaOH) slurry. The effects of current density, Fe2O3 mass fraction, temperature, and powder size on current efficiency and deposit morphology are investigated. A large quantity of dendritic iron structures is observed when experiments are carried out without stirring and/or applying heat from a heating plate. This condition suggests temperature and (ion/species) concentration gradients in the system. The dendrites are mainly deposited on the cathode's sides, corners, and edges. Different deposits and dendritic structures (compact layer deposit, moss-like deposit, deposit with whisker-like dendrites, and deposit with crystal-like dendrites) are observed as operating conditions change. Overall, a cathodic deposition of metallic iron with a high Faradaic efficiency (≥90 %) is successfully accomplished. The present findings provide new insights into the production of electrolytic iron powder and its future use as a carbon neutral and sustainable fuel/energy carrier.

Electromagnetic wave absorption properties of Mn0.4Zn0.6Fe2O4 powders synthesized by high-temperature mechanochemical method

Herein, spinel Mn0.4Zn0.6Fe2O4 powders were fabricated utilizing a novel high-temperature mechanochemical method (HTMC), which achieves the coupling effect of high-temperature and mechanical force in a single process. The microstructure, chemical composition, magnetic properties, and electromagnetic wave absorption (EMWA) characteristics of the Mn0.4Zn0.6Fe2O4 powders were thoroughly considered in 2–18 GHz. The results reveal that with a matching thickness of 4.3 mm and a frequency of 6.2 GHz, S3 exhibits an effective absorption bandwidth that covers 4.56–7.48 GHz and has a minimum reflection loss (RLmin) of −43.8 dB. The excellent EMWA properties of the Mn0.4Zn0.6Fe2O4 powders can be ascribed to their effective cooperation between dielectric loss and magnetic loss as well as favorable impedance matching. Considering the performance enhancement generated by the distinctive coupling of multiple mechanisms in HTMC and the excellent EMWA properties of the as-prepared single Mn0.4Zn0.6Fe2O4 powders, it has significant potential in the field of fabricating efficient MAMs.

An Experimental Study on the Sealing Mechanism of a Karst Pipeline by Dynamic Water Grouting

Aiming at the problem of water burst plugging in karst pipelines, in this paper, a new type of waterborne epoxy resin magnetic self-polymerization grouting material (WEMS) suitable for karst pipeline water burst plugging was developed, and a visual simulation test device for karst pipeline water burst grouting plugging was designed and built. Through the orthogonal test of grouting plugging, the influence of different factors on the effect of grouting plugging was analyzed, and the shear mechanism of magnetic slurry magnetization plugging was also analyzed. The results showed that (i) the best grouting sealing performance was achieved when the new WEMS had a water–cement ratio of 0.35–0.55 and Fe3O4 powder misery of 20–40%. (ii) The primary relationship between the factors affecting the dynamic water flow rate and slurry retention is Fe3O4 power ratio > plugging length > water–cement ratio. (iii) The relationship equation was established between the shear strength of magnetic self-polymerizing slurry and the magnetic field strength, blocking length, and slurry ratio.

Surface science insight note: A linear algebraic approach to elucidate native films on Fe3O4 surface

Standard materials are often used to obtain spectra that can be compared to those from unknown samples. Spectra measured from these known substances are also used as a means of computing sensitivity factors to allow quantification by X‐ray photoelectron spectroscopy (XPS) of less well‐defined materials. Spectra from known materials also provide line shapes suitable for inclusion in spectral models which, when fitted to spectra, permit the chemical state for a sample to be assessed. Both types of information depend on isolating photoemission signals from the inelastically scattered signal. In this Insight note, technical issues associated with the use of XPS of as received Fe3O4 powder sample surface are discussed. The Insight note is designed to show how linear algebraic techniques applied to data collected from a sample marketed as pure Fe3O4 powder are used to verify that XPS has been performed on chemistry representative of the sample. The methods described in this Insight note can further be utilized in elucidating complex XPS data obtained from thin films formed or evolved during cyclic/non‐steady use of complex (electro)catalyst surfaces, especially in the presence of contaminants.

Влияние механической обработки исходных реагентов на структурные и электрические свойства LiFeO2 керамики

This work investigates the effect of mechanical treatment of initial Fe2O3 and Li2CO3 powders on the structure and electrical properties of lithium ferrite ceramics of the chemical composition LiFeO2. Mechanical treatment was carried out in an AGO-2S ball mill for 60 minutes at a bowl rotation speed of 2220 rpm. Sintering of ceramic samples was carried out in a laboratory furnace at 1050 °C for 1 hour. Using X-ray phase analysis data, it was shown that the introduction of the mechanical treatment of powders leads to a decrease in the concentration of the α-LiFeO2 phase in ferrite ceramics from 97,9 to 93,9 wt.%, as well as an increase in the secondary LiFe5O8 phase from 2,1 to 6,1 wt.%. In this case, during sintering, a more homogeneous and finely porous structure of the samples was formed. Based on the temperature dependences of the electrical conductivity of the samples, it was established that changes in electrical resistance are associated both with the microstructure and with the processes of adsorption-desorption (depending on temperature) of gas from the surrounding atmosphere into ferrite ceramics. The ferrite ceramics obtained by mechanical treatment is of interest for its further use as an adsorption material for carbon oxides.