Kinetics of reduction of Fe2O3 to Fe3O4 by the constant temperature differential thermal analysis method
About: This article is published in Thermochimica Acta.The article was published on 1976-08-01. It has received 8 citations till now. The article focuses on the topics: Thermomechanical analysis & Differential thermal analysis.
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TL;DR: In this article, the hydrogen reduction of pure α-Fe 2 O 3 doped with foreign metal oxides employing a sensitive micro-gravimetric technique was carried out by a consecutive two-step mechanism via Fe 3 O 4, the overall rate being controlled by the topochemical reduction of Fe 3 o 4 while that of doped oxides and hematite ore takes place by a different mechanism involving the mixed ferrite formed.
119 citations
TL;DR: An interesting phase transformation from α-Fe2O3 to Fe3O4 at low-temperature hydrothermal conditions is observed and involves the formation of α- Fe2 O3 hexagonal plates, the dissolution of the α-fe2O 3 hexagonalplates, the reduction of Fe3+ to Fe2+, and the nucleation and growth of new Fe3 O4 polyhedral particles.
Abstract: Different phases of iron oxide were obtained by hydrothermal treatment of ferric solution at 200°C with the addition of either KOH, ethylenediamine (EDA), or KOH and EDA into the reaction system. As usually observed, the α-Fe2O3 hexagonal plates and hexagonal bipyramids were obtained for reaction with KOH and EDA, respectively. When both KOH and EDA were added into the reaction system, we observed an interesting phase transformation from α-Fe2O3 to Fe3O4 at low-temperature hydrothermal conditions. The phase transformation involves the formation of α-Fe2O3 hexagonal plates, the dissolution of the α-Fe2O3 hexagonal plates, the reduction of Fe3+ to Fe2+, and the nucleation and growth of new Fe3O4 polyhedral particles.
72 citations
TL;DR: The spin resonance properties obtained from fitting the FMR data clearly indicate that a large spin-orbit coupling was observed for the single phase Fe3O4 MNPs and excellent magnetic properties were obtained from the static magnetic measurements.
Abstract: Herein, we have presented a detailed investigation of the temperature effect on hydrothermal synthesis of Fe3O4 magnetic nanoparticles (MNPs). The appearance of single-phase cubic spinel Fe3O4 at and above critical temperature provides a clear indication that temperature plays a crucial role in the single-phase synthesis of the Fe3O4 MNPs. A detailed investigation of the structural, magnetic and spin dynamic properties of PEG-400 coated Fe3O4 MNPs synthesized by a facile hydrothermal method at different temperatures (120 °C, 140 °C, 160 °C and 180 °C for 16 hours) has been presented. The single-phase cubic magnetite structure with high crystallinity was found in the samples synthesized at 160 and 180 °C and confirmed from XRD results, whereas samples prepared at 120 and 140 °C are of mixed phase (α-Fe2O3 and Fe3O4). The magnetic hysteresis curves reveal that saturation magnetization and coercivity of MNPs enhanced systematically with the increase in the reaction temperature from 120 °C to 180 °C. Maximum saturation magnetization (88.98 emu g−1) and coercivity (134.16 Oe) were found for the sample synthesized at 180 °C. Furthermore, ferromagnetic resonance (FMR) spectra obtained for samples synthesised at higher temperatures indicate a lower value of the line width due to the high magnetic ordering in the samples. Also, the resonance field decreased, and the g-value increased due to enhancement in magnetization for the single-phase samples synthesized at higher reaction temperatures. The spin resonance properties obtained from fitting the FMR data clearly indicate that a large spin–orbit coupling was observed for the single phase Fe3O4 MNPs and excellent magnetic properties were obtained from the static magnetic measurements.
38 citations
TL;DR: In this paper, the use of a capillary tube mass flow meter for measuring residential natural gas consumption, where the flow rate is extremely low, was proposed, and the simulation was accomplished for a sample natural gas composition with 94.38% methane, resulting to an uncertainty equal to 1.83%.
30 citations
TL;DR: In this paper, an inductively coupled plasma-atomic emission spectroscopy is used to calculate the concentrations of surface crud and gamma spectrometry was used to determine the radioactivity of the corrosion products, as well as their axial distribution across the surface of the fuel rods.
25 citations
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