Influence of synthesis approach on structural and magnetic properties of lithium ferrite nanoparticles

Dar, M. Abdullah; Shah, Jyoti; Siddiqui, Waseem Ahmad

doi:10.1016/j.jallcom.2012.01.083

Cited by 34 publications

(12 citation statements)

References 44 publications

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“…Lithium ferrite is a soft ferrimagnetic material with cubic cell crystal lattice with inverse spinel structure in which Li cation occupy octahedral B positions. There are several studies that deal mainly with structural and dielectric properties of Li ferrites [7][8][9][10] . In particular C band contain uplink frequency for satellite telecommunications, ISM band for medical and industrial applications and also the IEEE 802.11a wi-fi system.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Hernández-Gómez

Graça

Muñoz

2018

Journal of Alloys and Compounds

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Lithium ferrites are well known materials due to its numerous technological applications especially in microwave devices. Lithium ferrite nanoparticles were prepared by sol-gel technique by means of Pechini method, and then annealed at different temperatures in 250-1000º C range. XRD confirms spinel formation with particles sizes in 15-700 nm range, with increased size with annealing temperature, whereas FTIR and Raman measurement confirm that single phase lithium ferrite with ordered cationic structure is obtained. Microwave magnetoabsorption data of the annealed lithium ferrite nanoparticles were obtained with a broadband system based on a network analyzer that operates up to 8.5 GHz. At fields up to 200 mT we can observe a broad absorption peak that shifts to higher frequencies with magnetic field according to ferromagnetic resonance theory. The amplitude of absorption, up to 85 %, together with the frequency width of about 5.5 GHz makes this material suitable as wave absorber. FMR parameters like resonance field, linewidth and broadening are analyzed in order to obtain the characteristic parameters and analyze the microwave behaviour.

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Section: Introductionmentioning

confidence: 99%

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Hernández-Gómez

Graça

Muñoz

2018

Journal of Alloys and Compounds

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“…Saturation magnetization M s stands low as 63.5 emu/g with H c = 310 Oe coercivity even down to 5 K temperature. A still poor magnetization 13.7 emu/g keeps in α-Li 0.5 Fe 2.5 O 4 ( D c ∼ 6 nm) prepared using a reverse microemulsion method, or 36.0 emu/g with H c = 160 Oe in a coprecipitated powder ( D c ∼ 12 nm), at 5.0 kOe field as it is sufficient to saturate a bulk sample M s = 63.5 emu/g at room temperature . Surface spins in a small magnet distribute in a noncollinear structure and serve as a “magnetic dead” layer as on couple collectively. − It propagates over few atomic thickness in a core–shell spin structure.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Surface Spins in Small Core–Shell Magnets of Li_0.35Zn_0.30Fe_2.35O₄ Bonds over a Carbon Surface and Tailored Magnetic Properties

2015

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A lithium zinc ferrite Li 0.35 Zn 0.30 Fe 2.35 O 4 breeds Fe 3+ /Fe 2+ spins via O 2of a network what is it governs its magnetic and other properties for applications. When the oxygen polygons on the cations bond over a sp 2 -carbon layer it keeps small crystallites of sample separated apart in single domains. Cuboids or rectangular prisms (D c = 25 nm average size) of the ferrite are formed on an inorganic-organic gel is burnt in a self-propagating combustion in air. On annealing at ≥400 °C, as a residual carbon burns out yields bared ferrite grow successively, D c ~ 65 nm in 2 h at 800 °C. Distinct facets grow over plates (crystallites) turn-up in a bonded carbon desorbs off the surface at higher temperatures. At room temperature, a maximum H c = 81 Oe (M s = 85.6 emu/g) is shown in ferrite bonds over a thin carbon layer on D c = 65 nm sample, with H c = 4 Oe and M s = 72.2 emu/gin a virgin sample D c = 25 nm. At ≥800 °C, a feroxol layer replaces carbon with 1150, 1325 and 1385 cm -1 phonon bands. A 7.2% larger M s = 88.0 emu/g (110.2 emu/g at 4 K) arises over theoretical value in multidomains (annealed 1200 °C). Microscopic models brief how a sp 2 -carbon layer tunes unique features of spin-dynamics in a core-shell magnet. sites randomly with O 2-(or vacancies) in a so-called disordered spinel β-phase (F d m space group) in a α→β phase transition over 735-755 °C. 4,5 Jović et al. 4 observed a partial Li + /Fe 3+ ordering in octahedral sites in Rietveld analysis of X-ray diffraction in D c = 10 nm sized crystallites. Significantly large number of surface atoms of an incomplete coordination shell arise in such small lattice of a high-energy β-phase. A part Li + (x) as on migrates to tetrahedral 8c sites can raise the net magnetic moment by a 2xFe 3+ -value per formula unit. Jović et al. 5 observed a core-shell α-Li 0.5 Fe 2.5 O 4 to be stable even in small crystallites (D c = 5-6 nm) as on a precursor prepared with ethylene glycol was fired at moderate temperature 300 °C in air. Uniquely, on average controlled lattice strain keeps it the low energy phase. Saturation magnetization M s stands low as 63.5 emu/g with H c = 310 Oe coercivity even down to 5 K temperature. A still poor magnetization 13.7 emu/g keeps in α-Li 0.5 Fe 2.5 O 4 ( D c ~ 6 nm) prepared using a reverse microemulsion method, or 36.0 emu/g with H c = 160 Oe in a co-precipitated powder (D c ~ 12 nm), at 5.0 kOe field as it is sufficient to saturate a bulk sample M s = 63.5 emu/g at room temperature. 22 Surface spins in a small magnet distribute in a noncollinear structure and serve as a "magnetic dead" layer as on couple collectively. 23-25 It propagates over few atomic thickness in a core-shell spin structure. In poor exchange such spins hardly pin-down along an applied field. Localized charges arise in an "electric dead layer" of an insulator. 25 Spins and charges in a magnetic-electric dead layer function together in spintronics. Lithium ferrites often peak-up net magnetization in a specific permutation of a partial nonmagnetic substitution on...

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“…pinned domain gets thermally activated. However, this behaviour is entirely different from the Hopkinson effect as hikes are observed near to the Curie point [44]. The 1,073 K annealed sample should change this T1 transition, as observed in the 773 K annealed sample.…”

Section: Magnetic Analysismentioning

confidence: 77%

A phenomenal behaviour of nanocrystalline NiFe2O4: influence of secondary and parasitic phases on structure and magnetic property

2015

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In this paper, we report the influence of secondary and parasitic magnetic phases on NiFe 2 O 4 (NFO) nanoparticles synthesised during citrate gel method. Annealing at 773 K showed the presence of secondary and parasitic phases, whereas annealing at 1,073 K for 3 h showed the quenching of the secondary and parasitic phases. X-ray diffraction (XRD) analysis confirmed the nickel ferrite phase, with a trace amount of a-Fe 2 O 3 peak found and other phases being not traceable. The observed a-Fe 2 O 3 peak vanished at 1,073 K annealing, and a single phase of nickel ferrite was formed. The surface morphology of the samples was studied by SEM, which showed the fine grains of nickel ferrite. Raman spectra of the annealed samples were measured and analysed in the range of 1,000-100 cm -1 . Further analysis of isothermal M-H curve, zero-field-cooled and field-cooled (ZFC-FC) measurement and thermo-magnetisation M (T) measurements were performed with the aid of vibrating sample magnetometer on the prepared samples. The measured ZFC-FC curve showed an existence of spin-glass behaviour due to the parasitic phase for 773 K annealed sample, which is quite difficult to be identified using XRD and Raman spectra. Further, we also observed the room temperature coercivity H c = 430 Oe from the M-H curve for the sample annealed at 773 K. Remarkably, both low-temperature and high-temperature M-T curve measurements showed the influence of secondary and parasitic phases for 773 and 1,073K annealed samples.

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Influence of synthesis approach on structural and magnetic properties of lithium ferrite nanoparticles

Cited by 34 publications

References 44 publications

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Dynamics of Surface Spins in Small Core–Shell Magnets of Li_0.35Zn_0.30Fe_2.35O₄ Bonds over a Carbon Surface and Tailored Magnetic Properties

A phenomenal behaviour of nanocrystalline NiFe2O4: influence of secondary and parasitic phases on structure and magnetic property

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Influence of synthesis approach on structural and magnetic properties of lithium ferrite nanoparticles

Cited by 34 publications

References 44 publications

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Synthesis, structural characterization and broadband ferromagnetic resonance in Li ferrite nanoparticles

Dynamics of Surface Spins in Small Core–Shell Magnets of Li0.35Zn0.30Fe2.35O4 Bonds over a Carbon Surface and Tailored Magnetic Properties

A phenomenal behaviour of nanocrystalline NiFe2O4: influence of secondary and parasitic phases on structure and magnetic property

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Dynamics of Surface Spins in Small Core–Shell Magnets of Li_0.35Zn_0.30Fe_2.35O₄ Bonds over a Carbon Surface and Tailored Magnetic Properties