Structure and microstructure evolution of hercynite spinel (Fe2+ Al2 O4) after annealing treatment

Jastrzębska, Ilona; Szczerba, Jacek; Błachowski, A.; Stoch, P.

doi:10.1127/ejm/2017/0029-2579

Cited by 31 publications

(15 citation statements)

References 46 publications

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“…Additionally, they have low thermal expansion coeffi cients that improve the thermal shock resistance of the basic refractories that are applied in cement rotary kilns. It is worth emphasizing that their ability to interdiffuse with a magnesia matrix [14] makes the material more fl exible through the local formation of secondary spinels. Therefore, the material is able to withstand thermal as well as mechanical strains that are constantly present in a rotating kiln [15].…”

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confidence: 99%

Structural properties of Mn-substituted hercynite

et al. 2017

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Abstract. In this work spinel series with the general formula Fe 1-x Mn x Al 2 O 4 (where x = 0, 0.3, 0.5 and 0.7) were synthesized and characterized with respect to their structure and microstructure. X-ray diffractometry (XRD) was used to identify the phase composition that revealed a single phase spinel material. Rietveld refi nements of the XRD patterns were carried out in order to determine the lattice and oxygen positional parameters of the spinel compounds. Mössbauer effect measurements were performed at room temperature to determine the local chemical environment of the Fe ions, their valences, and degrees of spinels inversion. It was shown that an increase in the Mn content led to a decrease in the ratio of Fe 2+ to Fe 3+ . The results obtained from Mössbauer spectroscopy (MS) were used to establish the chemical formulas of the synthesized spinels. Finally, the microstructure that was observed using scanning electron microscopy (SEM) showed a compact microstructure with an octahedral crystal habit.

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confidence: 99%

Structural properties of Mn-substituted hercynite

et al. 2017

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“…The results show that the amount of spinel does not change while the values of Hematite reduces during higher temperature calcination of the specimen. So, one can conclude that iron cations diffused from hematite into spinel structure [10,18]. Fig.…”

Section: Resultsmentioning

confidence: 82%

“…5, the peak intensity of hercynite decrease and a new phase appears. Annealing of hercynite for a long time at a high temperature in air leads to alteration of its phase composition [10]. In conjunction with the mentioned decomposition, a crystal phase appears, indicating a phase change.…”

Section: Resultsmentioning

confidence: 99%

“…They found that Kirkendall effect plays an important role during the in-situ formation of spinel [9]. Jastrzębska et al [10] also suggested a mechanism for decomposition of hercynite into FeAl2O4.Fe3O4, Fe3O4 and  -Al2O3, during heating at 1000 °C for 24 hrs.…”

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confidence: 98%

“…Jastrzębska et al prepared FeAl2O4-MgAl2O4 solid solution, using APS method. The product of their work was a compound of spinel with chemical formula as Fe 2+ 0.699Mg0.301Al1.941Fe 3+ 0.059O4 [8]. Sako et al investigated magnesium aluminate (MA) spinel formation mechanism.…”

Section: Introduction mentioning

confidence: 99%

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Magnesium Doped Hercynite: Preparation and Formation Mechanism

Rahmani-Boldaji¹,

Saeri²,

Otroj³

et al. 2018

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We investigated the formation mechanism of magnesium doped hercynite during reaction sintering process at 1400 ºC. A two-step synthesis procedure based on combining of spinel and ferrous chloride was considered here. Firstly, magnesium aluminate spinel was prepared by sol-gel method, using Al and Mg chlorides as raw materials. Then, the powder particles were dispersed in an aqueous solution of ferrous chloride in 1.5:1 molar ratio and the solution was stirred at 60 °C. After solvents removal, the thermal properties of a sample of the dried specimens were studied, using simultaneous thermal analysis (STA) method. Afterwards, the specimens were calcined at 400, 800, 1100 and 1400 ºC for 1, 3 and 6 hrs, under air atmosphere. X-ray diffraction (XRD) analysis, field emission scanning electron microscope (FESEM) and X-ray fluorescence spectroscopy (XRF) were used for characterization of the specimens. Study of the obtained results leads us to conclude that hercynite was formed thorough a diffusion-based mechanism, when heated to high enough temperatures. After heating for a prolonged period (6 hrs.) at 1400 °C, hercynite decomposes into its constituent oxides and also a new crystal phase appears. This new phase was identified as FeAlO3. The modified Scherrer, Williamson-Hall and Rietveld methods are also used to estimate the crystallite size of the as-synthesized magnesium doped hercynite.

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Phase Transformation of Hercynite During the Oxidative Roasting Process

Wang

Zhou

et al. 2020

JOM

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Structure and microstructure evolution of hercynite spinel (Fe2+ Al2 O4) after annealing treatment

Cited by 31 publications

References 46 publications

Structural properties of Mn-substituted hercynite

Structural properties of Mn-substituted hercynite

Magnesium Doped Hercynite: Preparation and Formation Mechanism

Phase Transformation of Hercynite During the Oxidative Roasting Process

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