Synthesis and magnetic properties of concentrated α-Fe2O3 nanoparticles in a silica matrix

Tadić, Marin; Marković, Darka; Spasojević, Vojislav; Kusigerski, Vladan; Remškar, Maja; Pirnat, Janez; Jagličić, Zvonko

doi:10.1016/j.jallcom.2006.09.099

Cited by 140 publications

(104 citation statements)

References 35 publications

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“…Unusual high value of coercivity H C ≈ 2850 Oe measured at 2 K, and the shape of hysteresis loop can be caused by additional antiferromagnetic interaction probably due to a dipolar interaction among particles or due to interaction of particles in core/shell structure [5]. DC magnetic data were fitted by both Langevin function for non-interacting particles and modified Langevin function for interacting nanoparticles [2][3][4][5][6]. The analyses of fitted procedure confirm the superparamagnetic behaviour of interacting particles in our system.…”

Section: Resultssupporting

confidence: 68%

“…This is qualitative confirmation of blocking/freezing process in Fe/Au nanoparticles system. The AC susceptibility data were fitted by both Arrhenius law valid for a system of non-interacting particles and by Vogel-Fulcher law describing system of interacting particles [2][3][4]6]. The quantitative analysis of χ due to the value of parameter C 1 = ∆T B /(T B ∆ log f ) = 0.00242 confirms the existence of inter-particle interaction in our system.…”

Section: Resultsmentioning

confidence: 54%

“…Below a critical size of particles, the magnetic moment in single domain fluctuates in direction due to thermal agitation, leading to superparamagnetic behaviour above the blocking temperature T B , and to spatial freezing of these moments below T B [3].…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, the nanoparticles of iron coated by gold (Fe/Au) were prepared by chemical method and their magnetic characteristics were analysed in the content of theoretical laws (Langevin function, Arrhenius law and VogelFulcher law) [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Study of the Fe Coated by Au Nanoparticles

Zeleňáková

Kováč²,

Kavečanský³

et al. 2008

Acta Phys. Pol. A

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Nanosized iron-gold magnetic nanoparticles with an average particle size 10 nm were prepared by a reverse micelle method. The magnetic properties measurements of DC and AC magnetization confirm behaviour typical of a superparamagnetic system, such as the irreversibility of the zero-field-cooled and field-cooled curves, the frequency dependence of a blocking temperature T B , and revealing of coercivity H C below blocking temperature. The quantitative analysis of AC susceptibility due to value of parameter C 1 = ∆T B /(T B ∆ log f ) = 0.0242 confirming the existence of inter-particle interaction in our system.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Study of the Fe Coated by Au Nanoparticles

Zeleňáková

Kováč²,

Kavečanský³

et al. 2008

Acta Phys. Pol. A

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“…Between TM and Neel temperature (TN) (~ 950K) it is weak ferromagnetic and above TN the hematite is paramagnetic [9,11]. These transitions are infl uenced by particle size, shape and crystallinity [9][10][11]. Particles smaller than 16 nm have a superparamagnetic behaviour at room temperature [12].…”

mentioning

confidence: 99%

Sonochemical Synthesis of Hematite Nanoparticles

Mihail¹

2015

ChemJMold

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Abstract. Hematite nanoparticles were prepared by a procedure consisting in sonication of μ 3 -oxo trinuclear iron(III) acetate of composition [Fe 3 O(OOCCH 3 ) 6 (H 2 O) 3 ]NO 3 •4H 2 O, {Fe 3 O}NO 3 as iron source, in strong basic conditions followed by thermal treatment at 600˚C. The formation of the hematite was confi rmed by IR spectroscopy, X-ray powder diffraction and Raman spectroscopy while, the shape and size of the nanoparticles and their agglomeration were evidenced and estimated on the basis of the images taken with TEM techniques.Keywords: hematite, nanoparticles, iron oxides, sonochemistry. There are various forms of iron oxides [7]. They differ in composition, in the valence of Fe and, above all, in crystal structure. The most stable and wide spread oxide phase of iron is α-Fe 2 O 3 , where Fe has the lower Gibbs free energy [8]. Hematite has hexagonal structure of the corundum type with a close-packed oxygen lattice in which twothirds of the octahedral sites are occupied by Fe(III) ions. Bulk hematite is antiferromagnetic till Morin temperature (TM) (~260 K). Between TM and Neel temperature (TN) (~ 950K) it is weak ferromagnetic and above TN the hematite is paramagnetic [9,11]. These transitions are infl uenced by particle size, shape and crystallinity [9][10][11]. Particles smaller than 16 nm have a superparamagnetic behaviour at room temperature [12].Hematite nanoparticles proved to be effective catalyst in numerous reactions such as the decomposition of soot and NO x in diesel exhausts [13], oxidation of CO [14], photocatalytic degradation of salicylic acid [15], and FischerTropsch synthesis [16]. An iron-based solid catalyst is also normally used as a Lewis acid catalyst and/or support in homogeneous and heterogeneous catalysis [17]. Hematite nanoparticles could be applicable in water treatment technology for removing metal [18]. Hematite has a bandgap of 2-2.2 eV thus being semiconductor suitable for photocatalytic water-splitting with hydrogen formation [19].The hematite nanoparticles could be obtained by different routes: co-precipitation [20], microemulsion method [20,21], thermal decomposition [20,22] Our approach in this study is to obtain hematite nanoparticles using μ 3 -oxo homotrinuclear {Fe 3 O}NO 3 acetate as an iron source and easy sonochemical route as a synthesis procedure. The obtained product was characterized by adequate techniques (FTIR, energy-dispersive X-ray spectroscopy, Raman spectroscopy, wide angle X-ray spectroscopy, transmission electron microscopy), in order to evaluate the formed structure.

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Tuning the Morphology of Metal Oxides for Catalytic Applications

Shen

2013

Nanocatalysis Synthesis and Applications

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Synthesis and magnetic properties of concentrated α-Fe2O3 nanoparticles in a silica matrix

Cited by 140 publications

References 35 publications

Magnetic Study of the Fe Coated by Au Nanoparticles

Magnetic Study of the Fe Coated by Au Nanoparticles

Sonochemical Synthesis of Hematite Nanoparticles

Tuning the Morphology of Metal Oxides for Catalytic Applications

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