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Basic yellow 28 dye, used extensively in the textile and leather industries, poses significant environmental and health risks, including allergic reactions, skin irritation, and respiratory problems. This study reports the Pechini sol-gel synthesis of novel ZnO/Mg3B2O6 nanostructures for the decontamination of basic yellow 28 dye from aqueous solutions. The nanostructures were synthesized by calcining at 650 and 850 °C for 5 h, producing ZM650 and ZM850, respectively. The average crystallite sizes were 39.28 nm for ZM650 and 51.03 nm for ZM850. BET surface areas were 70.71 m2/g for ZM650 and 48.13 m2/g for ZM850. FE-SEM and HR-TEM analyses revealed distinct morphological structures, with ZM650 exhibiting a dense aggregation of rod-like particles and ZM850 showing larger clusters. The maximum adsorption capacities were 381.68 mg/g for ZM650 and 303.03 mg/g for ZM850. The optimum adsorption was observed at a pH of 10, a contact time of 70 min, and a temperature of 298 K. Regeneration using a 6 M HCl solution demonstrated efficient reusability over five cycles. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm, indicating monolayer adsorption. Also, the adsorption process was found to be physical and exothermic. [ABSTRACT FROM AUTHOR]

MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h. [ABSTRACT FROM AUTHOR]

Abstract Basic yellow 28 dye, used extensively in the textile and leather industries, poses significant environmental and health risks, including allergic reactions, skin irritation, and respiratory problems. This study reports the Pechini sol-gel synthesis of novel ZnO/Mg3B2O6 nanostructures for the decontamination of basic yellow 28 dye from aqueous solutions. The nanostructures were synthesized by calcining at 650 and 850 °C for 5 h, producing ZM650 and ZM850, respectively. The average crystallite sizes were 39.28 nm for ZM650 and 51.03 nm for ZM850. BET surface areas were 70.71 m2/g for ZM650 and 48.13 m2/g for ZM850. FE-SEM and HR-TEM analyses revealed distinct morphological structures, with ZM650 exhibiting a dense aggregation of rod-like particles and ZM850 showing larger clusters. The maximum adsorption capacities were 381.68 mg/g for ZM650 and 303.03 mg/g for ZM850. The optimum adsorption was observed at a pH of 10, a contact time of 70 min, and a temperature of 298 K. Regeneration using a 6 M HCl solution demonstrated efficient reusability over five cycles. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm, indicating monolayer adsorption. Also, the adsorption process was found to be physical and exothermic.

Our contribution discusses the possibility of using spray drying synthesis for the preparation of active cathode material for Li-ion batteries. The particles were synthesized using a two-stage spray drying synthesis of NMC material (Li1.2Ni0.13Mn0.54Co0.13O2), when we separated the processes of synthesizing the nanoparticles (step 1) themselves and the subsequent calcination were separated from each other. Synthesis was based on spraying of precursor solution via ultrasonic atomizer and dried particles were captured using an electrostatic separator. During the following calcination step, the effect of temperature on the crystallization of the sample was investigated in the temperature range of 400–900 ℃. The temperature of 750 ℃ proved to be ideal for sufficient formation of a crystalline structure while maintaining a sufficiently fine-grained structure. At this temperature, the influence of the length of calcination was also investigated for the following times: 2.5, 5, 10, and 20 h. The structural and morphologic characterization of synthesized material was examined with X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. [ABSTRACT FROM AUTHOR]

MnZn ferrite powders were prepared based on the novel nano in situ composite method and through chemical sol-spray drying–calcination technology. The precursor powders were calcined at 1060 °C at different calcination times (1–9 h) to research the influences of the calcination time on MnZn ferrite powders. The research results revealed that all samples had similar morphologies composed of fine particles. The pure MnZn ferrite spinel phase can only be obtained when the calcination time does not exceed 3 h. Otherwise, some α-Fe2O3 or γ-Fe2O3 impurities will appear. The particle size descended with an increasing calcination time and then ascended. After 3 h of preservation, the smallest particle size was obtained, and it exhibited a unimodal distribution. The saturation magnetization (Ms) increased at first and decreased later with an increasing calcination time, and the optimal value (53.4 emu/g) was reached after holding for 3 h. In view of this work, the optimal calcination time is 3 h.

Cerium formate after the reaction of cerium nitrate with formic acid was used as raw material for calcination. The calcined products were characterized under different conditions, and the particle size, specific surface area, morphology, carbon content, nitrogen content and ratio of oxygen to cerium(abbreviated as O/Ce ratio) of the products were analyzed. The results show that the particle size and morphology after calcination are related to those before calcination. Cerium formate particles prepared by the reaction of 16 mol/L formic acid with cerium nitrate are agglomerates with rodlike structure before calcination. After calcination, the morphology remains unchanged and the particle size decreases slightly, and a large number of fine particles less than 0-100 μm are produced when the calcination temperature is higher than 700 ℃. While cerium formate particles prepared by the reaction of 20 mol/L formic acid with cerium nitrate are agglomerates close to spheres before calcination, and the morphology remains the same after calcination, but a large number of fine particles less than 0-100 μm are produced after calcination. The decrease of the specific surface area is caused by the decrease of the pore structure. With the increase of the calcination temperature, the crystal structure is rearranged and the defects in the lattice are reduced, resulting in the continuous reduction of pore structure. The C and N contents of the particles after calcination are mainly related to the calcination temperature. Increasing the calcination temperature can effectively reduce the C and N contents. The calcination time has little effect on the C and N contents. The crystal structure of cerium dioxide is stable, and the O/Ce ratio is basically maintained in the range of 2.000±0.010. Finally, for the two kinds of calcination processes of cerium formate, the calcination temperature is 700 ℃, the calcination time is 1 h, and sufficient amount of air or oxygen is introduced during the calcination.

Preparing calcium sulfoaluminate cement (CAS) from solid waste phosphogypsum (PG) instead of natural gypsum is an effective way to utilize solid waste. In this paper, CAS clinker was successfully prepared from PG and the mineral content of calcium sulfoaluminate ( C 4 A 3 S ¯ ) in the sample was above 65%. The effects of raw material ratio, calcination temperature, and time on clinker composition were investigated. The mechanical properties of different samples were tested. The optimum ratio for preparing CAS using PG was 42.23% limestone, 17.43% PG, and 40.34% bauxite. The optimal calcination conditions are a high temperature of 1250 °C for 45 min. The 3-day compressive strengths of the laboratory-prepared CAS were all above 50 MPa. It was found that as the calcination temperature increased, the amount of C 4 A 3 S ¯ produced gradually increased. Temperatures above 1300 °C resulted in the decomposition of C 4 A 3 S ¯ . The calcination time did not significantly affect the mineral composition of the clinker or the strength of the cement. C 4 A 3 S ¯ was observed to be rounded and hexagonal platelets with crystal sizes of 1 to 2 μm, a relatively small size that is favorable to the hydration of C 4 A 3 S ¯ , as observed by SEM images. In addition, the high calcination temperature affected the particle morphology of C 4 A 3 S ¯ , changing it from a well-defined polygonal structure to a molten state. The test results provide helpful information for improving PG utilization and applying PG in CAS production. [ABSTRACT FROM AUTHOR]

In this study, the synthesis of nanostructured NiMn 2 O 4 is achieved through the novel wet-chemical reduction synthesis method, maintained at a constant temperature of 500 °C. Variations in calcination time to 4, 5, and 6 h, with a constant synthesis temperature, result in the formation of NiMn 2 O 4 (NMO) nanostructures (NSs). These NMO-NSs are employed as electroactive materials in the assembly of electrochemical supercapacitors. Electrodes, composed of NMO-NSs calcined for 4 h, at constant temperature of 500 °C, are observed to exhibit a high specific capacitance/capacity of 966.7 F g−1 (579 C g−1) respectively, at a scan rate of 5 mV s−1. Retention of 96 % of the specific capacitance is noted after 5000 cycles of the as optimum electrode (NM-4 h). The significant influence of calcination time on the efficiency of electrochemical supercapacitors is highlighted in this research. An asymmetric supercapacitor device (ASSCs), featuring a wide working potential window of 0–1.6 V and a energy density of 38.9 W h kg−1 at a power density of 5 kW kg−1. As fabricated ASSCs demonstrates high specific capacitance of 109.4 F g−1/175 C g−1 with capacitance retention of 79.9 % over 5000 cycles. The potential of highly porous binary NiMn 2 O 4 NSs as suitable materials for high-performance supercapacitor devices is suggested by the findings. [Display omitted] • NMO-NSs are synthesized by novel wet-chemical reduction synthesis method. • NM-4 h electrode showed specific capacitance/capacity of 966.7 F g−1 (579 C g−1) in 1 M KOH. • NM-4 h electrode exhibited 96 % retention after 5000 cycles in 1 M KOH. • NM-4 h//AC ASSCs delivered energy density of 38.9 W h kg−1 with power density 5 W k g−1. [ABSTRACT FROM AUTHOR]

Abstract Changes in fluoride removal ability of chicken bone char (CBC) were investigated by both remained amounts of carbon including organic substances and crystallite size of hydroxyapatite in the CBC. Carbon contents in CBC were controlled by heating time at 600°C. Although temperature for crystal‐grain growth for HAp, 650°C, was higher than 600°C, crystallite size of HAp in CBC increased with heating time. Fluoride ion removal ability positively related to the amount of remaining carbon and negatively related to the square of crystallite size, as an index of surface area, of HAp. These results suggested that fluoride ion removal from water by CBC is not only by ion exchange and/or dissolution‐precipitation process, but also by adsorption by carbon and/or temporal capture of fluoride ion by microstructure of carbonate in CBC before immobilize it in apatite structure.

Bio-based silica gel is having many commercial significances in various sectors, such as medical, cleansing agents in industries, laboratory analysis, cosmetics, food additives, and so forth. In view of crucial requirements, this study aimed to synthesize and characterize the silica gel from Ethiopia’s primary post-harvest biomass residue, known as teff straw. The present study has been emphasized to investigate on the influence of calcination time for teff straw ash [Joshi et al 2022 Investigation of bamboo leaves as an alternative source of silica: extraction, characterization and its application as an adsorbent for methylene blue sequestration Chem. Select. 7 , e202200011] preparation between 2 to 5 h. Further, the specific surface area of the resultant TSA samples was examined for preliminary understandings of processing time. By adopting the standard procedures through template-mediated sol–gel process, acquired TSA samples were subjected to treatment with NaOH to result sodium silicate solution and the amorphous silica. From the findings, it was apparent that the yield of silica gel has significantly influenced by calcination time. Accordingly, the maximum yield (90.0%) was attained at the calcination time of 4 h at 900 °C. Further, physiochemical and morphological characteristics of acquired silica gels were ascertained using sophisticated instrumental techniques such as BET, FTIR, XRD, SEM, and EDX. The XRD analysis of the crystallographic characteristics showed that the silica extracted from TSA at 900 °C for 2, 3, 4, and 5 h was found to be in amorphous state. The surface morphological studies of silica gel samples have been carried out using SEM studied. the EDX spectra showed the negligible amount of other impurities, nevertheless a larger amount of silica was found with highest purity of 99.77% e silica gel was obtained in TSA calcinated at 3 h. FTIR spectrum confirmed the presence of siloxane (Si–O–Si) vibrations of amorphous silica that are responsible for the strong bend observed at 1070 cm ^−1 . It was found that the silica gel prepared at 3 h of calcination time had the largest specific surface area of 739.242 m ^2 g ^−1 , pore volume of 0.32 cm ^3 g ^−1 , and a pore diameter of 1.68 nm.

In this study, lead oxide (PbO) nanostructures are fabricated by an ultrasound-assisted sonochemical method, and re-ultrasonic effects on them are investigated. In the synthesis process, lead nitrate powder is used as a precursor, and potassium hydroxide serves as a precipitation agent. The resulting samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). Re-ultrasound is also performed to terminate the growth of the PbO nanorods, stabilize them, and preserve their morphology. According to the XRD results, the re-ultrasonic effect did not change the crystal phases, and the tetragonal and orthorhombic crystal phases were preserved. The effect of the calcination time was investigated too; an increase in it led to a decrease in the irregular nanorods size but an increase in the crystallite size.

Preparing calcium sulfoaluminate cement (CAS) from solid waste phosphogypsum (PG) instead of natural gypsum is an effective way to utilize solid waste. In this paper, CAS clinker was successfully prepared from PG and the mineral content of calcium sulfoaluminate (C4A3S¯) in the sample was above 65%. The effects of raw material ratio, calcination temperature, and time on clinker composition were investigated. The mechanical properties of different samples were tested. The optimum ratio for preparing CAS using PG was 42.23% limestone, 17.43% PG, and 40.34% bauxite. The optimal calcination conditions are a high temperature of 1250 °C for 45 min. The 3-day compressive strengths of the laboratory-prepared CAS were all above 50 MPa. It was found that as the calcination temperature increased, the amount of C4A3S¯ produced gradually increased. Temperatures above 1300 °C resulted in the decomposition of C4A3S¯. The calcination time did not significantly affect the mineral composition of the clinker or the strength of the cement. C4A3S¯ was observed to be rounded and hexagonal platelets with crystal sizes of 1 to 2 μm, a relatively small size that is favorable to the hydration of C4A3S¯, as observed by SEM images. In addition, the high calcination temperature affected the particle morphology of C4A3S¯, changing it from a well-defined polygonal structure to a molten state. The test results provide helpful information for improving PG utilization and applying PG in CAS production.

In this study, phosphogypsum-based composite cementitious materials (PGCMs) were prepared by adding fixed proportions of additives to calcined phosphogypsum (PG). Samples with dimensions of 40 × 40 × 80 mm and 150 × 150 × 300 mm were used to study the effect of the PG calcination time on the PGCM compressive strength, stress–strain relationship, and failure mode and its mechanism. The test results indicated that the PGCM compressive strength gradually increased as the calcination time increased. When the PG calcination time was 180 min, the compressive strengths of the smaller and larger samples increased by 3 and 3.6 times, respectively, compared with the strengths at a calcination time of 20 min. The main reason for the strength increase was the formation of ettringite and hydrated calcium sulfate dihydrate in the PGCM gel system. Additionally, the PGCM compressive strength was significantly related to the sample size, and its reduction coefficient was between 0.60 and 0.69 at different PG calcination times. As the PG calcination time increased, the peak stress of the PGCM stress–strain curve and the corresponding axial strain increased gradually; moreover, brittle failure became more evident.

Changes in fluoride removal ability of chicken bone char (CBC) were investigated by both remained amounts of carbon including organic substances and crystallite size of hydroxyapatite in the CBC. Carbon contents in CBC were controlled by heating time at 600°C. Although temperature for crystal‐grain growth for HAp, 650°C, was higher than 600°C, crystallite size of HAp in CBC increased with heating time. Fluoride ion removal ability positively related to the amount of remaining carbon and negatively related to the square of crystallite size, as an index of surface area, of HAp. These results suggested that fluoride ion removal from water by CBC is not only by ion exchange and/or dissolution‐precipitation process, but also by adsorption by carbon and/or temporal capture of fluoride ion by microstructure of carbonate in CBC before immobilize it in apatite structure. [ABSTRACT FROM AUTHOR]

Pd-doped SiO2 organic-inorganic hybrid materials were synthesized using sol-gel technique. The Pd-doped SiO2 samples were calcined at the temperature 350°C for several different time in air atmosphere with two different heating rates. Influence of calcination time and heating rate on the phase-chemical structure of Pd-doped SiO2 membrane materials was discussed by XRD, XPS, FTIR and TG-DTG analysis. The results indicate that the two factors have great influence on the crystal structure of Pd element and minor influence on the chemical structure. A longer calcination time and a slower heating rate can facilitate the oxidation of Pd0 to PdO, and should be conducive to the decomposition of Si-CH3 groups and the dehydration condensation of Si-OH groups. In order to prevent metallic Pd0 in Pd-doped SiO2 organic-inorganic membrane materials from being oxidized in air, the calcination time and heating rate should be chosen carefully. [ABSTRACT FROM AUTHOR]

A calcination time regulation method has been unprecedentedly used to adjust the orderly meso-structure of novel α-Fe 2 O 3 nanoclusters derived from MIL-100(Fe) (MIL: Materials of Institute Lavoisier). The as-synthesized magnetic orderly mesoporous α-Fe 2 O 3 nanoclusters were characterized by XRD, SEM, TEM, TGA, N 2 adsorption-desorption isotherms, VSM, Zeta potential, FTIR and XPS. The 6 h calcinated α-Fe 2 O 3 nanocluster exhibited the optimal properties, including the high specific surface area and the orderly mesoporous properties, which facilitate the arsenic(III,V) adsorption capacity. The maximum adsorption capacities of As(III) and As(V) were 109.89 and 181.82 mg g −1 , respectively, and adsorption equilibrium can be reached just within 30 min. The kinetics intra-particle diffusion model and adsorption isotherms reveal that the adsorption rate is controlled by pore diffusion and the adsorption process belongs to Langmuir monolayer adsorption. These results indicate that the orderly mesoporous structure of α-Fe 2 O 3 nanoclusters plays a key role in rapid and efficient adsorption for arsenic(III,V). Meanwhile, adsorption mechanism verifies that arsenic can react with active sites (Fe-OH) to form complexes by Fe-O-As bond. Moreover, α-Fe 2 O 3 nanocluster can be separated easily due to its excellent magnetism. Above all, the magnetism orderly mesoporous α-Fe 2 O 3 nanocluster is a promising adsorbent for emergent treatment of arsenic in practice. [ABSTRACT FROM AUTHOR]

Two commercially available TiO 2 (hexagonal-like and spherical-like particles) were used to investigate the effect of g-C 3 N 4 "melting" on the photocatalytic properties of g-C 3 N 4 /TiO 2 composites. Improvement in the contact between the components was observed when they were thermally treated at 350 °C for an extended period of time (between 2 and 72 h) due to the partial melting and phase fusion of g-C 3 N 4. Consequently, the enhanced contact between the phases allows easier injection of photogenerated electrons from the conduction band of g-C 3 N 4 into TiO 2 , improving charge carrier separation. The prepared composites were tested for bisphenol A degradation under visible-light illumination, which showed that the components that had been calcined for 24 h performed better due to the improved charge carrier separation. Superoxide anionic radicals and photogenerated holes were identified as active species in the photooxidation experiments conducted under visible-light illumination. [Display omitted] • All investigated g-C 3 N 4 /TiO 2 composites exhibit visible-light photocatalytic activity. • A prolonged calcination increases the photocatalytic activity of the composites. • The enhanced catalytic activity is attributed to improved g-C 3 N 4 /TiO 2 interface area. • The origin of the improved g-C 3 N 4 /TiO 2 interface area lies in the "melting" of g-C 3 N 4. • The main active species for the photooxidation of bisphenol A are O 2 − · and holes. [ABSTRACT FROM AUTHOR]

The influences of an NH4F additive content and calcination time on the morphological evolution of α-Al2O3 were investigated by using commercial γ-Al2O3 precursor as raw material. The results showed that the morphological evolution of α-Al2O3 was highly related to the addition of NH4F, the additive content, and the calcination time. Square-like α-Al2O3 powders with a primary crystal size of ~200 nm were formed from the milled γ-Al2O3 precursor with 1 wt.% NH4F at 1300°C for 2 h, whereas round cake-like, hexagonal platelets, slenderlike, and other irregularly shaped α-Al2O3 pieces in the size range of 0.2-2 μm were synthesized from the milled γ-Al2O3 precursor with 20 wt.% NH4F addition under the same calcination. Both morphological regularity and particle size distribution of α-Al2O3 were greatly facilitated by increasing the calcination time from 2 to 5 h. The addition of NH4F may lead to an alteration of the α-Al2O3 growth process by a change in the scale of the developing microstructure. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate that vertically grown ZnO nanowire (NW) arrays of the wurzite phase were successfully fabricated on fluorine doped tin oxide (FTO) substrates via a hydrothermal method. The coating of a seed layer onto the FTO substrates was found to favor the growth of a uniform ZnO NWs array which shows saturation in the photocurrent density with a relatively low potential bias. Furthermore, prolonging the calcination time of the seed layer makes the ZnO NWs behave the better charge separation and improve the photo-electrochemical performance. Under the irradiation at a 75 mW cm −2 from a simulated sunlight source, the ZnO NWs array electrode prepared from the seed layer with calcination at 350 °C for 5 h shows a saturated photocurrent density of 514 μA cm −2 and a maximum half-cell solar-to-hydrogen (HC-STH) efficiency of 0.26% was obtained at 0.6 V versus reversible hydrogen electrode (RHE) in neutral electrolyte. [ABSTRACT FROM AUTHOR]

Polycrystalline MFI zeolite membranes were prepared on α-alumina tubular support by hydrothermal treatments at 413 K. The synthesized zeolite membranes were characterized by XRD, SEM and single gas permeation. The influence of hydrothermal treatment steps and the calcination time on the zeolite layer formation were investigated. MFI zeolite membrane prepared by four subsequent hydrothermal treatments and calcined at 673K for 30 h had optimum quality from morphological and crystalline point of view. The grown MFI zeolite layer was uniform with about 20 µm thickness and well-intergrown zeolite crystals.

Highlights: [•] C-TiO2 thin films were successfully synthesized by modified sol–gel method based on the self-assembly technique. [•] Tween 80, one kind of hydrocarbon surfactants, was used as template and carbon precursor. [•] A thorough material characterization was performed to determine the effect of calcination time on the structural and optical properties of the synthesized catalyst films. [ABSTRACT FROM AUTHOR]

Magnesium oxide nanoballs with of 80–100 nm diameters were synthesized by chemical precipitation. The precursor magnesium hydroxide was prepared from dolomite ore as a raw material which was immersed in hydrochloric acid and then reacted with ammonium hydroxide without any surfactant. The effects of calcination temperature and time during the thermal decomposition of magnesium hydroxide precipitates on the crystal growth and morphology of the magnesium oxide particles were investigated by scanning electron microscopy and X-ray diffraction. The results show that the magnesium hydroxide layers collapsed on the (001) lattice surface and generated spherical grains of magnesium oxide with an increase in the calcination temperature. Magnesium hydroxide is completely decomposed to magnesium oxide after calcining at 400°C for 1 h. The crystallite size of the magnesium oxide increases with an increase in the temperature. The calcination time has no obvious effect on the size of the magnesium oxide grains. [ABSTRACT FROM AUTHOR]

The number of studies regarding sol-gel made titania powders is quite high, and nearly all of them use the calcination as the crystallization process. However, several papers are not providing crucial information regarding the calcination parameters, such as, heat treatment atmosphere, heating rate or heat treatment time. Furthermore, nearly no investigations were done regarding short calcination times and fast heating rates. The present paper points out the missing or under-evaluated aspects in the literature and demonstrates their importance throughout simple experiments. First of all, the influence of the calcination atmosphere and the applied flow rate (in tubular furnaces) was proven by demonstrating the inhomogeneity of the obtained samples. Secondly, the major influence of the chosen calcination time and rate was proven by obtaining fast heat treated titania powders. Their activity varied significantly with the applied calcination time, achieving two activity maxima. Also, the obtained activity trend shows that by varying the calcination time highly active titanias can be obtained (more active than Evonik Aeroxide P25). [ABSTRACT FROM AUTHOR]

Abstract: Nanostructured NiCo2O4 spinel was fabricated with a facile, low-cost coprecipitation process. The ethylene glycol was applied to serve as a stabilizer to govern over the nucleation, growth, and agglomeration processes. The influence of the calcination time was also studied on the coprecipitation reaction. Both the reaction conditions have statistically significant effects on the size distribution, crystallinity, electronic conductivity and the electrochemical performances of the products. The optimized, 5–10nm NiCo2O4 spinel, calcinated at 375°C for 8h, had excellent crystallinity and electric conductivity. It showed a superior-specific capacitance of 671Fg−1 at a current density of 1Ag−1. The delay in the specific capacitance was insignificant, after a 7000-cycle test, revealing the high stability of the product. The simplicity and practicability of the modified coprecipitation process may facilitate the successful commercial applications in electrochemical capacitors for nanostructured NiCo2O4 spinel. [Copyright &y& Elsevier]

Abstract: New Ni x Mg1−x Al2O4 nanosized in different composition (0.1≤ x ≤0.8) powders have been synthesized successively for first time by using low temperature combustion reaction (LTCR) of corresponding metal chlorides, carbonates and nitrates as salts with 3-methylpyrozole-5-one (3MP5O) as fuel at 300°C in open air furnace. Magnesium aluminate spinel (MgAl2O4) was used as crystalline host network for the synthesis of nickel-based nano ceramic pigments. The structure of prepared samples was characterized by using different techniques such as thermal analysis (TG–DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). UV/Visible and Diffuse reflectance spectroscopy (DRS) using CIE-L*a*b* parameters methods have been used for color measurements. The obtained results reveal that Ni x Mg1−x Al2O4 powder of samples is formed in the single crystalline and pure phase with average particle size of 6.35–33.11nm in the temperature range 500–1200°C. The density, particle size, shape and color are determined for all prepared samples with different calcination time and temperature. [Copyright &y& Elsevier]

Abstract: LiCoO2 powders are rapidly becoming important cathode materials in commercial lithium-ion batteries because of their excellent properties. In the present work, LiCoO2 powders were prepared using a novel sol–gel method with citric acid as a chelating agent, hydroxypropyl cellulose as a dispersant agent and LiNO3, Co(NO3)2·6H2O as starting materials. The effects of calcination temperature and the calcination time on the structure and morphology of LiCoO2 powders were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. According to the analysis, the crystallinity of LiCoO2 powders depends on the calcination temperature and calcination time. The results indicate the layered, pure and ultrafine HT-LiCoO2 powders can be obtained at 700°C for 4h in air. After 25 cycles, the electrode demonstrates the charge/discharge capacities at 175 and 154mAh/g, respectively, which will be suitable for high capacity cathode materials in rechargeable lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: The cathode material, LiNi0.9Co0.1O2 was prepared using a rheological phase reaction method with LiOH·H2O, home-made Ni(OH)2, and Co2O3 as starting materials. At first, the mixture of reactants and a proper amount of water reacted to form a rheological precursor. Then the dried precursor was heated at 730 °C in one step to yield the product. The effects of calcination time (between 0.5 and 10 h) on the structural, morphological and electrochemical properties were investigated. All obtained powders show a single phase with α-NaFeO2 structure (R–3m space group). The sample prepared in 2.5 h delivers the largest initial discharge capacity of 218 mA h g−1 (3.0–4.35 V, 25 mA g−1) and still remains 192 mA h g−1 after 15 cycles. The method is simple, economical and effective and is promising for practical application. [Copyright &y& Elsevier]

As a method of the fabrication process of YBa2Cu3O7-x (YBCO) coated conductors, the metalorganic deposition (MOD) process using metal trifluoroacetates (TFA) has been considered to be a strong candidate as a low cost fabrication process for coated conductors with high Jc.In the case of the MOD process using the TFA salts for the all three elements, it requires several tens hours in the calcination process for each single coated film to minimize the generation of pores in the film. In order to shorten the calcination time, a new combination of starting materials was developed. In this study, the new heating process for these new materials has been investigated. Consequently, the calcination time was shortened to be about 17%. Also, the overall transport Ic of 292 A and the Jc value of 2.0 MA/cm2 were achieved with 1.48 μm in thickness at 77 K in self-field. [Copyright &y& Elsevier]

This paper reports the results of an investigation aiming at finding what affects the grain size of nano-TiO2 powder during synthesis. Nano-sized TiO2 powders have been prepared by a sol–gel method. The crystalline structures and morphologies of the powder have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The result shows that the different preparation conditions such as concentration, pH value, calcination time and calcination temperature have a lot of influences upon the properties of nano-TiO2 powders. The smallest grain size of TiO2 powder we have obtained is 6 nm by controlling the process conditions. [Copyright &y& Elsevier]

[Display omitted] • Lead oxide (PbO) nanorods are synthesized via the sonochemical method under re-ultrasonic effects. • Re-ultrasonic treatment is an efficient method of terminating the growth of PbO and stabilizing it. • The re-ultrasonication method can be used to reduce the size of particles without changing their initial morphology. In this study, lead oxide (PbO) nanostructures are fabricated by an ultrasound-assisted sonochemical method, and re-ultrasonic effects on them are investigated. In the synthesis process, lead nitrate powder is used as a precursor, and potassium hydroxide serves as a precipitation agent. The resulting samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). Re-ultrasound is also performed to terminate the growth of the PbO nanorods, stabilize them, and preserve their morphology. According to the XRD results, the re-ultrasonic effect did not change the crystal phases, and the tetragonal and orthorhombic crystal phases were preserved. The effect of the calcination time was investigated too; an increase in it led to a decrease in the irregular nanorods size but an increase in the crystallite size. [ABSTRACT FROM AUTHOR]

Praseodymium doped zirconium silicate pigments (Pr x Zr 1-x SiO 4) were synthesized by a solid-state reaction, and the influence of praseodymium fraction (x ​= ​0.03, 0.05 or 0.07), temperature (900, 1000, 1100 or at 1200 ​°C) and calcination time (6, 12, 24 or 48 ​h) was simultaneously tested to determine their effect on colorimetric properties. The chromatic properties are associated with the volume of the unit cell; thus, with the amount of Pr4+ that is integrated into the crystal structure, the ascending concentration of the Pr4+ into zircon structure increases the color intensity only in the range where the unit cell volume is close to 261 ​Å3, lower or higher values result in pigments with lower yellow intensities. An intense reddish-yellow tone can be reached delimited by praseodymium fraction of 0.03 and 0.05, temperature between 900 and 1100 ​°C, and 6 ​h of calcination time. [Display omitted] • Pr4+ into zircon structure increases the color intensity if the unit cell volume is close to 261 ​Å3. • An intense reddish-yellow tone can be reached delimited by praseodymium fraction of 0.03 and 0.05 • An intense reddish-yellow tone can be reached between 900 and 1100 ​°C. • An intense reddish-yellow tone can be reached at 6 ​h of calcination time. • Pigment green tone increases if is synthesized with high calcination time and temperature and high praseodymium fraction. [ABSTRACT FROM AUTHOR]

Various LiNi 0.02 Mn 1.98 O 4 cathode materials were synthesized via a solid-state combustion approach at 500 °C for 1 h and further calcination at 700 °C through optimizing the calcination time. All obtained LiNi 0.02 Mn 1.98 O 4 samples are determined to be spinel structure with a single crystalline polyhedral morphology. As the extended calcination time, the particle size distribution increase from 170 nm to 260 nm. The unique polyhedral morphology endows the LiNi 0.02 Mn 1.98 O 4 with an abundant exposed {111} crystal planes to alleviate the manganese dissolution. What is more, the truncated portion is along the {110} and {100} crystalline orientations that is conductive to supporting Li+ diffusion. The optimal LiNi 0.02 Mn 1.98 O 4 sample prepared at 700 °C for 3 h shows good electrochemical property with capacity retention rate of 63.1%, 67.1%, and 74.1% after 1000 cycles at 1, 5 and 10 C, respectively. Even at elevated temperature of 55 °C or high current rate of 20 C, the durable cycling performance is still achieved up to 1000 cycles. • LiNi 0.02 Mn 1.98 O 4 samples were prepared via a facile solid-state combustion. • LiNi 0.02 Mn 1.98 O 4 samples display a single crystalline polyhedral morphology with various surface-oriented. • The optimal LiNi 0.02 Mn 1.98 O 4 has the excellent high rate capability and elevated temperature cycle performance. [ABSTRACT FROM AUTHOR]

Nanostructured titanium dioxide has been synthesized using both conventional and ultrasound assisted sol-gel technique with an objective of understanding the role of cavitational effects in the synthesis process. The experiments were conducted at a constant calcination temperature of 750 °C and the calcination time was varied from 30 min to 3 h to study the effect of calcination time on the properties of the synthesized TiO₂. The TiO₂ specimens were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of the sonication time on the phase transformation process from anatase to rutile and also on the crystallite size and percentage crystallinity of the synthesized TiO₂ has also been investigated. It was observed that 100% phase transformation occurred after 3 h of calcination for the ultrasound assisted sol-gel synthesized TiO₂. The study on the phase transformation via variation of sonication time yielded interesting results. It was observed that as the sonication time increased, an initial increase in the rutile content is obtained and beyond optimum sonication time, the rutile content decreased. In general, the ultrasound assisted process results in synthesis of TiO₂ material with higher rutile content as compared to the conventional sol-gel process., (Copyright © 2014 Elsevier B.V. All rights reserved.)