Increasing Calcination Temperature Research Articles

Effect of calcination temperature on structure evolution of hematite nanoparticles

The objective of this study is to investigate the transition structure of iron oxide, specifically the change from magnetite to hematite, as well as the influence of calcination temperature on the structural growth of hematite nanoparticles. The magnetite was extracted from the native iron sand in Indonesia using the coprecipitation procedure. To generate hematite, magnetite was calcined at various temperatures (350, 500, 650, and 800 °C). The structural changes resulting from the effect of calcination temperature were investigated by combining a number of characterisation methods. The crystal structure was examined using synchrotron x-ray diffraction (SRD) and the local structure was examined using x-ray absorption spectroscopy (XAS). Crystallite size was calculated using the Debye-Schrerrer equation at the most dominant SRD peak. Surface morphology was investigated using scanning electron microscopy (SEM). SRD data revealed that the sample calcined at 350 °C displayed both the Fe3O4 and α-Fe2O3 phases, while higher temperatures revealed the single-phase α-Fe2O3. Furthermore, an increase in calcination temperature was shown to be associated with an increase in crystallinity and crystallite size. For the samples H350 and H800, the crystallinity increased from 95.56 to 98.17%. In the magnetite, H350, H500, H650, and H800 samples, the crystallite size increased from 9.57 to 29.55, 16.40, 28,48, 29.26, and 29.55 nm. Higher calcination temperatures, on the other hand, increase the interatomic distance while decreasing the Debye–Waller factor, according to XAS fitting data. It can be inferred that around 500 °C, the transition from Fe3O4 to single-phase α-Fe2O3 was observed. While a greater calcination temperature of at least 800 °C would alter the structural parameters, it would not affect the phase.

Production of Porous Biochar from Cowdung and its Application

Porous activated carbon (PAC) powder is prepared from solid bio-waste - cow dung samples (CD). UV- Spectroscopy confirms the absorption rate of activated porous biochar at different concentration solutions(in ppm).The activation process is carried out by phosphoric acid and sodium hydroxide treatment followed by calcination at different temperature condition. XRD pattern confirms the amorphous phase formation with graphitic nature for different precursor utilization. SEM analysis shows the uniform and hierarchical porous network formation and aggregated particle with tiny. X- ray analysis confirms the formation of graphitic carbon and porous morphology for sample activated at increased calcination temperature. The elemental composition of as prepared carbon samples is determined by SEM and confirms the formation major carbon content existence. The obtained product is observed for the dye removal process wherein the specific amount of PAC is added to the Methylene Blue(MB) dye solutions and the absorption rate is observed through uv-spectroscopy.

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

Effect of process conditions on the performance of LiNi0.815Co0.15Al0.035O2 positive electrode material powder synthesized by hydrothermal approach

LiNi0.815Co0.15Al0.035O2 (NCA) lithium-ion battery cathode material was prepared using a hydrothermal approach. XRD and SEM analyzed the crystal parameters and powder morphology of the cathode material. The results show that the nickel cobalt precursor exhibits a petal-like morphology, and the nanoneedle primary particles are randomly distributed. Accompanied by the increase in calcination temperature and time, the peak intensity ratio of I003/I104 tends to decrease and then increase. The peak intensity ratio reached a maximum when the NCA sample calcined at 750°C for 8 h, indicating the lowest extent of Li/Ni mixing and the best electrochemical performance of the positive electrode material.

Resource utilisation of hazardous aluminium dross and coal gangue for fibre-reinforced cemented foam backfill

The resource utilisation of hazardous aluminium dross and coal gangue for fibre-reinforced cemented foam backfill can enhance the stability of filling stopes and address environmental issues. Herein, aluminium dross was first co-calcined with quicklime at 800°C, 950°C and 1,100°C to prepare modified foaming agents, and their phase transformations during calcination were analysed. Next, the calcined mixes, cement, coal gangue and fibres were employed to prepare the samples. The expansion ratio and hydration evolution—as well as the strength, deformation and heavy metal–leaching behaviours—of the fibre-reinforced cemented foam backfill were comprehensively investigated. Experimental results reveal that partial elemental Al in raw aluminium dross becomes active in the C12A7 and CA2 forms, which enhances the hydration reactivity of the calcined mixes. The efficient denitrification achieved at 1,100°C is because of the coupled effects of quicklime dispersion and high-temperature calcination. The grindability of the calcined mixes initially improves and subsequently worsens with increasing calcination temperature, which is related to the Al2O3 crystallinity. Active Al in the calcined mixes is conducive to hydration at an early age, leading to the generation of larger quantities of Hc/Mc and the AH3 gel and a smaller amount of portlandite. Owing to the coupled effects of the porous structure and fibre reinforcement, the fibre-reinforced cemented foam backfill exhibits good mechanical performance and large plastic deformation. Furthermore, the M1-10, M2-10 and M2-30 samples possessing an expansion ratio of 4%–10%, a compressive strength of >3 MPa and a good ability to stabilise heavy metals are excellent choices for the practical application of foam backfill technology in mining engineering.

Comparison Study of a Thermal-Driven Microstructure in a High-Ni Cathode for Lithium-Ion Batteries: Critical Calcination Temperature for Polycrystalline and Single-Crystalline Design.

High-Ni layered oxide cathodes are promising candidates for lithium-ion batteries due to their high energy density. However, their cycle stability is compromised by the poor mechanical durability of the particle microstructure. In this study, we investigate the impact of the calcination temperature on microstructural changes, including primary particle growth and pore evolution, using LiNi0.88Mn0.08Co0.04O2 (N884), with an emphasis on the critical calcination temperature for polycrystalline and single-crystal designs in high-Ni cathodes. As the calcination temperature increases, the primary particles undergo a rectangular growth pattern while the pore population decreases. Beyond a certain critical temperature (in this case, 850 °C), a sudden increase in primary particle size and a simultaneous rapid reduction in the pore population are observed. This sudden microstructure evolution leads to poor cycle retention in N884. In contrast, single-crystal particles, free of grain boundaries, synthesized at this critical temperature exhibit superior cycle retention, underscoring the significance of microstructural design over crystalline quality for achieving long-term cyclability. Our study sheds light on the interplay between calcination temperature and microstructural evolution, proposing the critical temperature as a key criterion for single-crystal synthesis.

Optical and electrochemical properties of manganese oxide (Mn3O4) nanoparticles: Investigating the influence of calcination temperature on supercapacitor performance

In this study, we investigate the influence of calcination temperature on the structural, optical, and electrochemical properties of Mn3O4 nanoparticles synthesized through a chemical co-precipitation route. Field-Emission Scanning Electron Microscopy (FESEM) images depict the formation of highly agglomerated, spherical-shaped particles. At calcination temperatures of 700 °C and 900 °C, the observation reveals the emergence of flat pellets and rod-like structures. The X-ray Diffraction (XRD) patterns confirm the presence of the Mn3O4 phase in M0 and M1 samples. However, the sample calcined at 500 °C (M3) showed a mixed phase of Mn3O4 and Mn2O3. Upon further calcination at 700 and 900 °C, this mixed phase undergoes complete transformation into the Mn2O3 phase. The change in absorption onset and photoluminescence intensity of samples is found with an increase in calcination temperature due to the crystal growth and phase modification. Furthermore, the synthesized samples are employed as electrode materials for supercapacitor applications. The sample calcined at 300 °C (M1) in three-electrode system demonstrated the specific capacitance (Csp) of 273.3 F/g at 0.5 A/g in an alkaline medium. The asymmetric cell assembled by using M1 and Hibiscus cannabinus stem-derived carbon material (HBC-900) delivered higher Csp of 205.7 F/g at 0.5 A/g. In addition, asymmetric supercapacitor device exhibited a high energy and power density of 43.1 Wh/kg and 476.2 W/kg with 82.07 % of initial Csp retention over 10,000 cycles at 10 A/g, which makes the sample M1 as the potential electrode material for supercapacitor application.

Solvent free fabrication and thermal tuning of copper oxide-zirconium dioxide nanocomposite for enhanced photocatalytic efficacy

Recently, several methods has been used for the synthesis of bimetal oxide nanocomposite, however, very few studies are available on the solvent free mechanochemical synthesis of nanomaterials. In this study, mortar and pestle assisted fabrication of copper oxide-zirconium dioxide nanocomposite (CuO–ZrO2 NC) was carried out and was calcined at 300, 600 and 900 °C. The variation in crystallographic parameters was examined through x-ray diffraction (XRD) and the crystallite size was found to be gradually increased with increasing calcination temperature. The morphological changes with increasing calcination temperature were traced during scanning electron microscopy (SEM) analysis. The percentage elemental composition was verified through energy dispersive x-ray (EDX) spectroscopy whereas the functional group analysis was done through Fourier transform infrared (FTIR) spectroscopy, where the intensity of peaks assigned to hydroxyl moiety decreased with increasing calcination temperature. The CuO–ZrO2 NCs were used as a photocatalysts for the degradation of the Fluorescein in the presence of solar light and highest photodegradation (77.27%) was noticed for the CuO–ZrO2 NC calcined at 900 °C.

Robust, thermally insulating, and high-temperature resistant phosphate-enhanced mullite fiber porous ceramic composites

Porous mullite ceramics with high porosity and low thermal conductivity are urgently required as high-temperature thermal insulators in harsh environments. How to improve the strength of Porous mullite ceramics dramatically under the premise of no sacrificing its thermal insulating properties has remained an extremely challenging. Inspired by the freezing rain phenomenon in nature, high-strength and high-temperature resistant phosphate coatings were applied to the surface of mullite fibers, which significantly improved the mechanical properties of porous mullite ceramics without significantly increasing their thermal conductivity. The Al(H2PO4)3 solution concentration significantly affected the mechanical and thermal properties of the composite material, where the mechanical performance improved with an increasing Al(H2PO4)3 solution concentration. The phosphate coating phase stabilized with an increasing calcination temperature. The mechanical properties of the ceramics were improved by the excellent interfacial bonding strength between the coating and mullite fiber, and the forms of phosphate in the porous ceramics. The optimum composite preparation process increased its compressive strength by approximately nine-fold to 4.1 MPa and resulted in a thermal conductivity of only approximately 0.09 W/(m·K), demonstrating that the composite exhibited a significantly higher comprehensive performance than other previously reported porous ceramics and aerogels. Such new composites with excellent mechanical and thermal insulation properties exhibit excellent potential for high-strength thermal insulation in the chemical, metallurgical, pharmaceutical, aerospace, and other fields.

Heat-acid treatment of georgian and kazakhstani natural heulandite-chabazites

The article considers the processes leading to a change in the structure and properties as a result of thermal treatment followed by acid treatment of natural zeolites from the Rkoni plot of the Tedzami deposit, Georgia, containing up to 80% of heulandite and 10% of chabazite, and from the Chankanay deposit, Kazakhstan, containing up to 70% of heulandite-chabazite mixture, selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources. The influence of preliminary heat treatment of the studied natural zeolites on weight loss, the processes of dealumination and decationization during subsequent acid treatment, and the adsorption properties of the final products is described. It has been shown that mass loss is minimal for amorphized samples, dealumination and the participation of sodium ions in the decationization process slow down significantly, and the adsorption capacity for water and benzene sharply decreases with increasing calcination temperature; all these effects are clearly pronounced for heulandite-containing Rkoni tuff, and for the more acid-resistant Chankanay zeolite they are manifested to a lesser extent.

Nanoscopic hygrometry: Exploiting porous nature zinc-doped tin oxide nanoparticles for enhanced humidity sensing at ambient temperature

This study focuses on zinc-doped tin oxide nanoparticles (Zn-SnO2 NPs) as promising humidity sensors. Through a chemical coprecipitation method, we synthesized Zn-SnO2 NPs and explored the influence of calcination temperature on their properties. X-ray diffraction confirmed the tetragonal rutile structure, and morphological analysis revealed a cauliflower-like morphology with enhanced porosity after calcination. UV-Visible absorption spectroscopy and photoluminescence measurements demonstrated a blue shift in the absorption peak and significant emission peaks related to oxygen vacancies, indicating improved humidity sensing potential as increasing the calcination temperature. The controlled calcination process led to successful outcomes, precisely tuning the NPs structure and optical behavior for enhanced humidity sensing capabilities. Conductivity studies have highlighted the semiconducting behavior of the NPs and observed that an increase in calcination temperature reduces their conductivity. Notably, humidity sensing experiments revealed a remarkable response of 93% and an exceptional response time of 30 seconds for the calcined NPs, surpassing the uncalcined sample. The sensing mechanism involving physisorption, chemisorption, and capillary condensation of water molecules on the NPs surface was validated. Moreover, the stability test over two month demonstrated consistent and highly stable humidity sensing response, reaffirming the NPs potential as effective and reliable humidity sensors.

Effect of calcination temperatures on optical and magnetic properties of FeWO4 nanoparticles

Abstract Calcination temperature is a crucial parameter that can be easily controlled to induce a change in material properties. Herein, iron tungstate (FeWO4) was synthesized via a hydrothermal method using iron(II) sulfate heptahydrate and sodium tungstate dihydrate as precursors and calcined at the temperature between 300 oC and 700 oC. With increasing calcination temperature, the saturation magnetization of FeWO4 nanoparticles decreased from 6.6 emu/g for FeWO4 to 0.4 emu/g for FeWO4_700, whereas their band gaps increased from 1.95 eV for FeWO4 to 2.20 eV for FeWO4_700. More crystallinity and crystal defects, and morphological changes at higher calcination temperatures contributed to varying magneto-optical properties of FeWO4 nanoparticles.

Hydrophilic sol-gel TiO2 coating on procaine-loaded injector needle for painless clinical treatments

Titanium dioxide (TiO2) coatings are demanded in clinical applications due to their biocompatible, porosity, and semiconducting properties. Drug release studies take advantage of these unique aspects of TiO2 for painless injection for those who have to take medicine through the injection frequently. In this study, TiO2 was prepared via the sol-gel method with Titanium tetra isopropoxide (TTIP) precursor in alcohol solvent for pH 3, 4, and 5 values. The prepared solution was coated on stainless steel substrates and injectors via dip coating. Following these steps, samples were calcinated at various temperatures (100°C, 300°C, 500°C, 700°C). The structural, physical, and chemical composition, chemical bond, wettability, and drug-release properties of coated samples were researched. Contact angle values affirmed that high temperatures and ultraviolet (UV)-light irradiation made samples more hydrophilic (26°±5° at 700°C for pH 4). Procaine, a short-time period local anaesthetic, was chosen as a model drug. Increased calcination temperature and raised hydrophilicity led to improve the released drug amount. Drug release studies were carried out using Franz diffusion cells at 36.5°C. Samples at 500°C calcinated released the highest amount of drug (90%) for 45 sec injection time. This study shed light on how TiO2 coating can be successfully utilized for clinical applications in the future.

Structural and antibacterial properties of copper oxide nanoparticles: a study on the effect of calcination temperature

Nanoparticles of copper oxide were synthesized by the simple precipitation method. The influence of calcination temperature on the structural characteristics and antibacterial activity of the nanoparticles were evaluated. The nanoparticles were analyzed by Bruner-Emmett-Teller (BET) surface area and pore size analyzer, x-ray diffraction, transmission electron microscope and scanning electron microscope. The findings demonstrated the formation of copper oxide nanoparticles showing a monoclinic phase. Before calcination, the nanoparticles showed a high BET surface area with rod shape morphology and size range between 18–70 nm and after calcination, irregular spherical-like morphology with size range of 20–200 nm was observed. However, it was evident that the BET surface area decreased gradually with increasing calcination temperature, while the nanoparticle size increased forming an irregular spherical shape. Subsequently, the copper oxide nanoparticles demonstrated that they are highly effective for bacteria inactivation. The inactivation activity was found to be more effective with uncalcined nanoparticles than with calcined nanoparticles. This was due to the large nanoparticle sizes and the decrease in surface area obtained after calcination. Thus, it was noted that calcination of the as-prepared nanoparticles significantly affects the structural and antibacterial properties. Hence, for antibacterial application, calcination was not necessary as the nanoparticles showed excellent antibacterial results.

Effect of calcination temperature on structural, magnetic, and dielectric properties of Mg0.75Zn0.25Al0.2Fe1.8O4 ferrites

Based on the desire to improve material properties, the effects of temperature have begun to be investigated. It was found that for nano-sized powder materials, such as ferrites, the structural properties like crystal structure and grain size, as well as many magnetic and electrical properties depending on them, change with the calcination temperature. Considering these changes, the effect of calcination temperature on the structural, magnetic, and electrical properties of MZA ferrites (Mg0.75Zn0.25Al0.2Fe1.8O4) prepared by co-precipitation was investigated in this study. The produced MZA ferrites were calcined at three different temperatures (600, 700, and 800 °C). The X-ray diffraction results showed that the samples exhibited a cubic spinel structure. It was found that the crystal sizes (D_sch) calculated using the Debye-Scherrer equation increased with increasing calcination temperature (22.47, 33.53, and 42.53 nm). From the Williamson–Hall (W–H) plots, crystal sizes were calculated almost same as Debye–Scherrer crystal sizes. The nano-sized particles were examined by scanning electron microscope (SEM). Elemental analysis was performed using EDX. ν1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ u }_{1}$$\\end{document} and ν2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ u }_{2}$$\\end{document} absorption bands and O–H and C–H vibrations were detected in the FTIR spectra. Magnetic measurements were carried out at room temperature and in the range of ± 60 kOe under the applied field. Magnetic results are explained by superparamagnetism. Dielectric measurements were performed at room temperature and a frequency range of 20 Hz to 10 MHz. The dielectric properties can be explained by Maxwell–Wagner theory. Impedance spectroscopy study revealed that the relaxation mechanism is consistent with the Cole–Cole model. In AC conductivity studies at room temperature, it was found that the sample calcined at 600 °C would be suitable for energy storage devices.

Transforming seafood waste: Green mussel shell-derived hydroxyapatite as a catalyst for spirooxindole synthesis

Utilizing bioresources and renewable materials represents a sustainable approach in chemical reactions. This study aims to harness seafood waste from green mussel shells as a raw material to produce hydroxyapatite (HAp) and employ it as a heterogeneous catalyst for synthesizing spirooxindole compounds. The green mussel shells underwent varying temperature calcination to yield CaO, subsequently utilized in HAp synthesis. XRD analysis exhibited the characteristic peak pattern of HAp and revealed a reduction in crystal sizes with increased calcination temperatures for CaO formation. Additionally, FTIR analysis identified the constituent functional groups of HAp in the sample. SEM analysis revealed irregularly shaped HAp particles, with average sizes of 268.42 nm (HAp-800), 212.46 nm (HAp-900), and 184.6 nm (HAp-1000). Using HAp as a catalyst in synthesizing spirooxindole yielded a 64 % product yield and demonstrated reusability. Utilizing mussel shell-derived hydroxyapatite as a catalyst offers a cost-effective and environmentally friendly approach to achieving higher product yields.

Contribution of micropores in porous zirconia spheres to high optical transparency of dental resin composites.

Transparency to UV-Vis light and radiopacity of dental resin composites containing zirconia (ZrO2) fillers were investigated. The transparency of the resin composite containing porous ZrO2 spheres was much higher than that containing irregularly shaped ZrO2 particles. Calcination of the porous ZrO2 spheres at high temperatures led to dramatically reduced specific surface areas and pore volumes. The transparency of the resin composite containing the calcined porous ZrO2 spheres drastically decreased as the calcination temperature increased. Then, the enhanced UV-Vis transmittance of the resin composite containing porous ZrO2 spheres is attributed to the concentration and physical characteristics of the pores. The radiopacity of the resin composites containing porous ZrO2 spheres increased slightly with increasing calcination temperature. This study revealed that the internal structure of the ZrO2 fillers mainly influenced in the UV-Vis light transmittance of the resin composites.

Effect of calcination temperature on Co/sepiolite catalyst for hydrogen production by ethanol steam reforming: Co speciation from phyllosilicate to spinel

Hydrogen production via ethanol steam reforming (ESR) was conducted over amorphous sepiolite (SEP) supported Co based catalysts, deeming as a green and sustainable strategy for renewable energy. However, the subtle regulation to the ESR reactivity of Co/SEP catalysts still remains a challenge. Given the structure sensitive property of ESR, calcination temperature, as a vital regulation parameter, was used to control the key physicochemical properties of catalysts. By various characterization techniques, the results revealed that a calcination temperature mediated metal-support interaction was manifested in the form of Co speciation evolution. With increasing calcination temperature, the occurrence states of Co species change from Co oxides to Co-phyllosilicate then to Co-Al spinel. The ESR experiments indicated that Co/SEP-600 catalyst possessed a suboptimal activity via a dehydrogenation route and a 50 h stability due to a compromising among Co-phyllosilicate dominated MSI, texture, Co0 nanoparticle size and acid-base property. The further improvement of calcination temperature only brought about a poor stability of Co/SEP-700 with a phase transformation or a low activity of Co/SEP-800 with an irreducible Co-Al spinel. Hence, the interaction type of Co with SEP framework Si/Al atoms determined the ESR reactivity of the catalysts, which was modulated by the calcination temperature. Additionally, abundant graphitic coke deposition on the agglomerated Co0 grains was attributed the weak MSI, such as Co/SEP-400, while a slight coke deposition appeared at Co/SEP-800 with an irreducible Co-Al spinel phase.

Generation and role of novel catalytic sites for NH3-SCR in bio-derived Chlorella@Mn denitration catalyst driven by calcination temperature

More conventional low-temperature denitration catalysts are prepared chemically, and the active sites are mainly metal oxides. In this paper, the catalysts are prepared biologically, and novel denitration active sites of nonmetal-oxygen-metal are formed. The NOx conversion was first increased and then decreased with the increase of calcination temperature, and was below 20 % at 200 ℃ at a reaction temperature of 175 ℃, and was close to 100 % at calcination temperatures of 365 ℃ and 435 ℃, and was below 80 % at 600 ℃. Compared to the Chlorella@Mn catalyst prepared at 435 ℃, which possesses the highest specific surface area (104.7 m2/g), the Chlorella@Mn catalyst prepared at 365 ℃ possesses stronger NOx and NH3 adsorption performance, which is related to the presence of a large number of P-O-Mn and C-O-Mn bonds, the presence of P-O-Mn bond could enhance the electron transfer between P and Mn, C-O-Mn bond can enhance the redox performance. The calcination temperature between 365 ℃ and 435 ℃ is the equilibrium range for denitration performance. L-H and E-R reaction mechanisms presence on Chlorella@Mn catalysts at calcination temperatures from 305 ℃ to 600 ℃, the presence of P-O-Mn and C-O-Mn bonds can also promote the generation of active nitrate species. This study will provide some reference for research on the formation of novel denitration active sites using biological methods.

Effect of calcination temperature of titanium dioxide (TiO2) on adsorption performance of doxycycline hydrochloride

In this work, titanium dioxide (TiO2) was synthesized at different calcination temperatures by sol-gel method using butyl titanate as raw material. The effect of calcination temperature on the crystallinity and adsorption properties of TiO2 were investigated at 300 °C, 450 °C and 600 °C, respectively. The characteristics of TiO2 were analysed by X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption-desorption analyzer and zeta potential tester. The results showed that the crystal type, specific surface area and zeta potential of TiO2 nanoparticles changed with the increase of calcination temperature and the best performance of anatase crystals happened at the calcination temperature of 300 °C (TiO2@300) for doxycycline hydrochloride (DCH) adsorption. The equilibrium adsorption capacities of DCH was 28.97 mg/g with DCH removal rate of 86.92% at 0.03 g TiO2@300 addition in 100 ml 10 mg/L DCH solution. TiO2@300 could be a promising adsorbent.