Synthesis and magnetic properties of hard/soft SrFe12O19/Ni0.7Zn0.3Fe2O4 nanocomposite magnets

Radmanesh, Maral; Ebrahimi, S.A. Seyyed

doi:10.1016/j.jmmm.2012.05.008

Cited by 96 publications

(25 citation statements)

References 34 publications

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“…xFexO3) [37] and Mn substitution at the Fe site (SrFe12-xMnxO19) has brought a reduction in the Ms values [31]. Ideally, the saturation magnetization of the composite consisting of hard and soft phases can be measured as [15,38] M = Ms,hard (1−fs) + Ms, soft × fs (1) where Ms,hard is the saturation magnetization of hard-phase SFO, Ms,soft is the saturation magnetization of soft-phase LSMO, and fs is the weight fraction of the soft phase in the composite. The measured value of 34.93 emu/g for the Ms of the composite with 40 wt % LSMO is about 38% lower than that predicted by Equation (1).…”

Section: Resultsmentioning

confidence: 99%

“…It has been reported earlier that Fe substitution to Mn sites of LSMO (La 0.67 Sr 0.33 Mn 1−x Fe x O 3 ) [37] and Mn substitution at the Fe site (SrFe 12−x Mn x O 19 ) has brought a reduction in the Ms values [31]. Ideally, the saturation magnetization of the composite consisting of hard and soft phases can be measured as [15,38]…”

Section: Resultsmentioning

confidence: 99%

“…Recently, many studies on exchange-coupled hard-soft composites have been reported, where ferrites are used as a magnetically soft-phase, such as SrFe 10 Al 2 O 19 /NiZnFe 2 O 4 [6], SrFe 12 O 19 /γ-Fe 2 O 3 [7], CoFe 2 O 4 /Fe 3 O 4 [8] [12], and SrFe 12 O 19 /La 0.7 Sr 0.3 MnO 3 [13]. However, the exchange-coupling phenomenon in many of these composites is not fully realized due to the intricate fabrication methods, microstructural and interfacial complexities, and the formation of secondary phases, factors which inhibit realization of full exchange-coupling between the hard-soft phases of composites [14,15]. The presence of incomplete exchange-coupling adversely affects the magnetic properties of the composite.…”

Section: Introductionmentioning

confidence: 99%

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Exchange-Coupling Behavior in SrFe12O19/La0.7Sr0.3MnO3 Nanocomposites

2019

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Magnetically hard-soft (100-x) SrFe12O19–x wt % La0.7Sr0.3MnO3 nanocomposites were synthesized via a one-pot auto-combustion technique using nitrate salts followed by heat treatment in air at 950 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) were used to characterize the structural and magnetic properties of the samples. XRD spectra revealed the formation of a mixture of ferrite and magnetite phases without any trace of secondary phases in the composite. Microstructural images show the proximity grain growth of both phases. The room temperature hysteresis loops of the samples showed the presence of exchange-coupling between the hard and soft phases of the composite. Although saturation magnetization reduced by 41%, the squareness ratio and coercivity of the nanocomposite improved significantly up to 6.6% and 81.7%, respectively, at x = 40 wt % soft phase content in the nanocomposite. The enhancement in squareness ratio and coercivity could be attributed to the effective exchange-coupling interaction, while the reduction in saturation magnetization could be explained on the basis of atomic intermixing between phases in the system. Overall, these composite particles exhibited magnetically single-phase behavior. The adopted synthesis method is low cost and rapid and results in pure crystalline nanocomposite powder. This simple method is a promising way to tailor and enhance the magnetic properties of oxide-based hard-soft magnetic nanocomposites.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exchange-Coupling Behavior in SrFe12O19/La0.7Sr0.3MnO3 Nanocomposites

2019

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“…One way to vary the magnetic properties is to modulate the composition of the spinel pillars along their length, producing for example a pillar with a hard and a soft layer. Nanocomposite or bi‐layer thin films made from exchange‐coupled soft and hard magnetic materials show an enhanced remanence and large magnetic energy product, exceeding what is expected from the components without exchange coupling . Several groups have reported hysteresis loop tuning and magnetization reversal in exchange‐coupled ferromagnetic hard/soft bi‐layers by changing the thicknesses and magnetic properties of the layers .…”

Section: Introductionmentioning

confidence: 99%

Compositionally Modulated Magnetic Epitaxial Spinel/Perovskite Nanocomposite Thin Films

Kim

Aimon

Sun

et al. 2013

Adv Funct Materials

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There is great interest in self-assembled oxide vertical nanocomposite fi lms consisting of epitaxial spinel pillars in a single crystal perovskite matrix, due to their tunable electronic, magnetic, and multiferroic properties. Varying the composition or geometry of the pillars in the out-of-plane direction has not been previously reported but can provide new routes to tailoring their properties in three dimensions. In this work, ferrimagnetic epitaxial CoFe 2 O 4 , MgFe 2 O 4 , or NiFe 2 O 4 spinel nanopillars with an out-of-plane modulation in their composition and shape are grown in a BiFeO 3 matrix on a (001) SrTiO 3 substrate using pulsed laser deposition. Changing the pillar composition during growth produces a homogeneous pillar composition due to cation interdiffusion, but this can be suppressed using a suffi ciently thick blocking layer of BiFeO 3 to produce bi-pillar fi lms containing for example a layer of magnetically hard CoFe 2 O 4 pillars and a layer of magnetically soft MgFe 2 O 4 pillars, which form in different locations. A thinner blocking layer enables contact between the top of the CoFe 2 O 4 and the bottom of the MgFe 2 O 4 which leads to correlated growth of the MgFe 2 O 4 pillars directly above the CoFe 2 O 4 pillars and provides a path for interdiffusion. The magnetic hysteresis of the nanocomposites is related to the pillar structure.

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“…1,2 Several approaches to the issue have been undertaken, [3][4][5] out of which enhancement of the properties of nanostructured ferrites through the use of the exchangespring effect has gathered large efforts. [6][7][8][9] In this type of magnets, exchange-coupling at the interface between magnetically hard and soft particles leads to an increase in saturation magnetization (M s ) and remanence (M r ) that overcomes the loss of coercivity in yielding larger energy products. 10 Unfortunately, owing to the fact that effective exchange-spring is a quantum-mechanical effect that appears at coherent atomic interfaces in particles below a certain critical size, strict structural restrictions apply.…”

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confidence: 99%