Mössbauer Spectroscopy in Study of Nanocrystalline Iron Oxides From Thermal Processes

Machala, Libor; Frydrych, Jiří; Pěchoušek, Jiří; Zbořil, Radek

doi:10.1002/9781118714614.ch18

Cited by 5 publications

(3 citation statements)

References 124 publications

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“…When fitting, widely accepted physicochemical models for ε-Fe 2 O 3 and α-Fe 2 O 3 were adopted and appropriately adjusted. 9,80 The appearance of the Mössbauer spectral profile of ε-Fe 2 O 3 reflects its crystal structure; each sextet corresponds to respective ε-Fe 2 O 3 crystallographic sites. Since all three octahedral and one tetrahedral sites in ε-Fe 2 O 3 are fully occupied with Fe 3+ ions, their sextets show relative spectral areas equal to 1 : 1 : 1 : 1 (with an assumption of an identical Mössbauer-Lamb factor for all the four different sites).…”

Section: Resultsmentioning

confidence: 99%

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems

2022

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Section: Resultsmentioning

confidence: 99%

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems

2022

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“…The sextet present in the spectra could be attributed to iron oxide (i.e. α-Fe 2 O 3 ) (Tuček et al, 2013).…”

Section: Mössbauer Spectroscopymentioning

confidence: 96%

Study of adsorptive materials obtained by wet fine milling and acid activation of vermiculite

Węgrzyn

Stawiński

Freitas

et al. 2018

Applied Clay Science

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Wet fine milling, as a pretreatment step to acid activation of vermiculite, was applied in order to decrease the environmental impact of the procedure commonly used to increase the mineral's adsorption capacity. Milling caused fragmentation of the material and several changes in its structure: edges of the flocks became frayed, the surface cracked, cation exchange capacity (CEC) increased, and most of the iron in oligonuclear and bulk form was removed. At the same time the specific surface area, crystallinity, chemical composition and adsorption capacity did not change significantly. Fine ground material was more susceptible to acid activation, which caused a decrease in the crystallinity and CEC, development of meso-and microporosity, an increase in the total volume of pores, in the specific surface and external surface areas. Micropores were developed faster in lower acid concentrations in the rough ground material, while the external surface area and total pores volume increased faster in the fine ground vermiculite. The latter material also had a higher CEC. Application of 0.5 mol L −1 HNO 3 to rough ground vermiculite did not change its adsorption capacity, however it changed from 55 ± 7 to 110 ± 8 mg g −1 when the material was fine ground. The optimal treatment conditions for both materials were obtained for 1.0 mol L −1 HNO 3 , however the adsorption capacity for the fine ground vermiculite increased more (i.e., from 55 ± 7 to 136 ± 7 mg g −1) than for its rough ground counterpart (i.e., 52 ± 7 to 93 ± 7 mg g −1). Concentrations higher than 1.0 mol L −1 resulted in deterioration of the adsorption capacities in both cases. Considering all the experimental outcomes, it can be concluded that the environmental impact of acid activation of vermiculite may be diminished by application of fine grinding of the material before the chemical activation process. Such treatment resulted in higher adsorption capacity at a given acid concentration compared to the rough ground material.

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“…The most frequently occurring polymorphs are alpha (α‐Fe 2 O 3 ) and gamma (γ‐Fe 2 O 3 ) form, mineralogically known as hematite and maghemite, respectively. The other two polymorphs, beta (β‐Fe 2 O 3 ) and epsilon (ε‐Fe 2 O 3 ), are very rare and due to the role of surface energy, they can exist only in the form of nano‐objects …”

Section: Introductionmentioning

confidence: 99%

Crystal Structure‐ and Morphology‐Driven Electrochemistry of Iron Oxide Nanoparticles in Hydrogen Peroxide Detection

Jakubec

Malina

Medřík

et al. 2018

Adv Materials Inter

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Various iron oxide nanoparticles with different morphologies are synthesized and subsequently tested for their conductivity and electrocatalytic activity toward hydrogen peroxide. The morphology and chemical and phase composition of iron oxide nanoparticles are evaluated employing scanning electron microscopy, X‐ray diffraction, 57Fe Mössbauer spectroscopy, and Brunauer–Emmett–Teller specific surface area measurements. The electrochemical properties of the as‐prepared sensors are estimated by electrochemical impedance spectroscopy. It is found that α‐Fe2O3 nanoparticles with the sticks morphology exhibit the best conductivity response among all the tested phases and morphologies. Moreover, it is predicted that conductivity of different iron oxides can be connected with a number of vacancies in their crystal structure. Furthermore, the influence of surface area and porosity of the material on the conductivity can be omitted. Finally, the electrocatalytic activity of iron oxide nanoparticles toward hydrogen peroxide is confirmed by means of cyclic voltammetry. The obtained results perfectly reflect those derived from electrochemical impedance spectroscopy and indicate that glassy carbon electrodes modified with the sticks morphology of α‐Fe2O3 hold a huge potential for hydrogen peroxide detection.

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Mössbauer Spectroscopy in Study of Nanocrystalline Iron Oxides From Thermal Processes

Cited by 5 publications

References 124 publications

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems

Study of adsorptive materials obtained by wet fine milling and acid activation of vermiculite

Crystal Structure‐ and Morphology‐Driven Electrochemistry of Iron Oxide Nanoparticles in Hydrogen Peroxide Detection

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Mössbauer Spectroscopy in Study of Nanocrystalline Iron Oxides From Thermal Processes

Cited by 5 publications

References 124 publications

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe2O3 nanoparticle systems

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe2O3 nanoparticle systems

Study of adsorptive materials obtained by wet fine milling and acid activation of vermiculite

Crystal Structure‐ and Morphology‐Driven Electrochemistry of Iron Oxide Nanoparticles in Hydrogen Peroxide Detection

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An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems

An effect of scandium substitution on the phase purity and structural, magnetic, and electrochemical features of ε-Fe₂O₃ nanoparticle systems