Papers by Keyword: Calcination Temperature

Abstract: Metal oxide nanoparticles are widely used in various fields, including catalysis, sensing, energy storage, and more. Manganese dioxide (MnO₂) is a promising material for gas sensors due to its sensitivity to various gases, including oxidizing and reducing gases. The calcination temperature affects their size, crystallinity, surface area, and other properties. In the present research work, the influence of calcination temperature on the structural, electrical and gas sensing properties of MnO₂ nanoparticles or nanopowders was investigated. The MnO₂ nanopowder was calcinated at 200, 400, 600, and 800 °C in a muffle furnace for 4 hours. After that, using the calcinated powder of MnO₂, the thick films were prepared using the standard screen printing technique. The structural characterizations were investigated using SEM, EDS, and XRD. It has been found that as the calcination temperature is increased, the electrical, structural, and gas-sensing properties of MnO₂ change. The prepared thick films calcinated at 200, 400, 600, and 800 °C are labeled as samples 1, 2, 3, and 4, respectively, in this paper. It has been found that sample 4 shows maximum resistivity, a more specific surface area, a smaller crystallite, and a maximum gas response to H₂S gas. The maximum sensitivity was found to be 76.32% to H₂S gas at operating temperature 120 °C. The response and recovery time was also found quickly.

Abstract: Photocatalyst activity relates to the active surface area between pollutants and catalyst compounds. The insertion of Al atoms as a substantial defect in ZnO structures can reduce the particle size thus the active surface area increases. Another way to raise the photocatalytic activity of ZnO is by combination with other oxide materials such as TiO₂ (Titanium dioxide). In this study, the ZnO-Al:TiO₂ powder was successfully prepared via the sol-gel method using zinc acetate dihydrate as a precursor, 0.5wt% of aluminum nitrate nonahydrate as a dopant precursor, and TiO₂ anatase. In order to understand the role of the combination of these two metal oxides, the concentration ratio of ZnO-Al and TiO₂ was varied by 1:1 (ZAT) and 4:1 (ZA4T) under low (150°C) and high (450°C) temperature calcination. Photocatalytic testing was carried out using a 3.2 ppm methylene blue (MB) solution under UV-A lamp irradiation for 120 minutes. The high calcination temperature facilitates the growth of ZnO-Al. Besides that, the different ratio concentrations and calcination temperatures produce different defect states in each sample. The most optimum results in the photocatalytic activity performed by ZnO-Al:TiO₂ 150°C (ZAT 15) with degradation rate constant (k) of 0.033/min and efficiency of 97% for MB removal. The unexpected zinc vacancies defect is estimated produce at the samples in high-temperature calcination. This defect type can accelerate electron-hole pair recombination. In Addition, samples with high-temperature calcination were considered to have lower hydroxyl/oxygen bonds on the surface thus affecting the photocatalytic performance.

Abstract: This paper studies how the various calcination temperatures affect the structural properties of Barium Titanate (BaTiO₃) and (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9) (BCZT) using solid-state reaction methods. BaTiO₃ and BCZT powders are calcined at various temperatures ranging from 1100°C–1300°C. Using X-ray diffraction, the phase formation, crystal structure and crystallite size of BaTiO₃ and BCZT powders were determined. The cubic crystal structure has been formed for BaTiO₃ and BCZT. At 1200°C, the reaction between BaCO₃ and TiO₂ was complete to produce BaTiO₃ composition. For BCZT composition were not fully react based on the phase structure in XRD due to impurity peak. Next, the crystallite size of BaTiO₃ powder becomes larger with increasing calcination temperature. Meanwhile, BCZT crystallite size becomes smaller when the calcination temperature is increased has discussed at the end of this paper.

Abstract: This article reflects the results of a set of studies on obtaining a face ceramic brick of soft molding with the search for raw materials and the development of an optimal production technology. It proposed and formulated the basic requirements for opoka-like rocks for the production of various types of wall ceramic products. They include recommendations on the chemical composition and such physical, mechanical and technological properties as density in the piece, natural humidity, porosity, mineral composition, compressive strength of the baked samples, fire shrinkage, water absorption, average density, etc. We proposed the so-called "soft molding" as a production technology. It is based on the principle of filling individual forms with a ceramic mass that has a certain plasticity and binding capacity. The appearance of such a brick is characterized by the absence of smooth edges and sides and rounded corners. The sand used for spilling forms produces a special effect of velvety and old-looking brick. The conclusions based on the results of laboratory and technological research as well as factory tests revealed the great promise for using opoka-like rocks as a raw material for the production of face ceramic bricks of soft molding.

Abstract: By using an acid free wet chemical method, porous nano-ZnO with high photocatalytic performance was synthesized from galvanizing dross at room temperature. The route is an environmental way to realize high value conversion and reuse of galvanizing dross. X-ray diffraction, microstructure, electron diffraction and specific surface area analyses show, the prepared porous nano-ZnOs are hexagonal wurtzite structure ZnO strips. The strips are consist of ZnO nanoparticles, the strips growth direction is perpendicularly to the C axis when the calcination temperature is up to 350°C. With the increase of calcination temperature, the specific surface area of ZnO decreases and the crystallinity increases. The photocatalytic activity of nano-ZnO is related to its crystallinity and grain size. When the calcination temperature is 400°C and the calcination time is 2h, the nano-ZnO has been completely crystallized, the ZnO particle size is uniform and is about 20 nm, the photocatalytic activity is the best and can reach up to 95%.

Abstract: Nano sized ZrO₂ nanopowder was synthesized by precipitation method. Phase transformation was investigated as a function of calcination temperature by XRD, SEM , and FT-IR. It is indicated that the thermal anneling from 400 to 800 °C resulted in increasing the average crystallite size from 12 to 20 nm. As the calcination temperature increased, the crystallite size and the agglomeration were increased. The increase in the monoclinic content and grain growth are caused by the calcination temperatures even calcination at 800 °C.

Abstract: TiO₂ and iron-doped TiO₂ were synthesized by sol-gel method. TiO₂ and 0.5 %mol Fe:TiO₂ were calcined at 500 and 800 °C for 3 h. The synthesized particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-VIS diffuse reflectance spectrophotometry (UV/DRS), scanning electron microscopy (SEM) and scanning electron microscope-energy dispersive X-Ray analysis (SEM-EDX). The XRD patterns of all samples that were calcined at 500 °C showed only anatase phase. On increasing temperature from 500 to 800 °C, the anatase phase transformed to rutile phase. For 0.5 %mol Fe:TiO₂, pseudobrookite (Fe₂TiO₅) phase was observed at 800 °C. The particles that contained rutile showed higher antibacterial activities against E. coli, B. subtilis, and S. aureus than anatase phase, under fluorescent irradiation.

Abstract: Nickel-rich layered oxides (Ni ≥60%) are considered as the most promising cathode materials for lithium-ion batteries due to its high energy density and low cost. However, its cycling performance is seriously influenced by the synthesis condition, like the sintering temperature, time and atmosphere. Herein, we investigate different properties of LiNi_0.83Co_0.11Mn_0.06O₂ (LNCMO) sintered from 720 to780 °C, and the cathode calcined at 760 °C display the most perfect layered structure and the uniform distribution of primary particles size. Therefore, the LNCMO sintered at 760 °C exhibited the best rate capability of 118 mAh·g^-1 at 10 C and the highest capacity retention of 95.44 % after 100 cycles at 1 C. Our results indicate that the cycling performance and rate capability of LNCMO are heavily depended on the sintering temperature.

Abstract: The uniform hexagonal barium ferrite powders were synthesized by co-precipitation method using metal chloride. The effects of the amount of hexadecyltrimethyl ammonium bromide (CTAB), the water bath and calcination temperature on the phase formation, microstructure and density of barium ferrites were systematically investigated. The results showed that the formation of uniform hexagonal barium ferrite powders was significantly influenced by the amount of CTAB and the water bath could lead to the larger grain size and density. The SEM demonstrated that the BaFe₁₂O₁₉ powders had plate-like shape with crystallite sizes varing from 150 to 200 nm. When the amount of CTAB was 0.2g/100ml and the calcination temperature was 850 °C, the barium ferrite powders were uniform which indicated that the amount of surfactant and calcination temperature were very optimum.

Abstract: Selective catalytic hydrogenolysis of glycerol on Os/bentonite catalyst represents a low cost and green route for 1,2-propanediol which is major commonity chemical used in the production of antifreeze functional fluids, paints and humectants. The experimental results combined with the characterization studies using TPR, FESEM-EDX and XPS techiniques revealed that the optimum calcination temperature was 300 °C with glycerol conversion obtained was 80.7%. This might be due to the presense of Os metal species as a active site with binding energy (BE) of Os 4f at 51.2 eV in XPS analysis. TPR profile also shows two obvious peak at reduction temperature of 95 °C and 140 °C represent for Os³⁺ and Os⁴⁺ species respectively. The presence of Os³⁺ and Os⁴⁺ species were also confirmed by XPS analysis.