High-Temperature Magnetic Behaviour of 10 % Aluminium-Substituted Cobalt Ferrite

Kumar, Lawrence; Kumar, Pawan; Zope, Mukesh Kumar; Kar, Manoranjan

doi:10.1007/s10948-016-3965-5

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…Furthermore, our result is comparable to the earlier reports on cobalt ferrite nanopartieles 63, 64 . It is noticed that at 300 K, the K 1 values increases with x up to x=0.10, thereafter it follows a decreasing trend.…”

Section: Fe-sem and Eds Analysissupporting

confidence: 92%

Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

2015

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In this work, we have focused on the influence of Gd 3+ substitution in structural, magnetic and electrical properties of cobalt ferrite synthesized by using sol-gel auto combustion method. The powder x-ray diffraction analysis reveals that the Gd-substituted cobalt ferrites crystallize in single phase spinel structure for lower concentrations of Gd 3+ , while a trace of GdFeO 3 appears as a minor phase for higher concentrations. Raman and Fourier transform infrared spectra confirm the formation of spinel structure. Furthermore, Raman analysis shows that the inversion degree of cobalt ferrite decreases with Gd 3+ doping. The field emission scanning electron microscopy images show that the substitution of small amount of Gd 3+ causes considerable reduction of grain size. Studies on magnetic properties reveal that the coercivity of Gdsubstituted cobalt ferrites enhances from 1265 Oe to 1635 Oe and the saturation magnetization decreases monotonically from 80 emu/g to 53.8 emu/g and the magnetocrystalline anisotropy constant increases from 5.8x10 5 erg/cm 3 to 2.23 x10 6 erg/cm 3 at 300 K. The electrical properties show that the Gd 3+ doped samples exhibit the high values of dielectric constant (616 at 100 Hz) and ac conductivity (4.83x10 -5 S/cm at 100 Hz) at room temperature. The activation energy is found to decrease from 0.408 to 0.347 eV in for the rise of Gd 3+ content. The impedance study 2 brings out role of bulk grain and grain-boundary towards the electrical resistance and capacitance of cobalt ferrite. Gd-substitution and nano size of cobalt ferrite enhance the electrical and magnetic properties which could ensure a higher memory storage capability. IntroductionSpinel ferrites with the general formula MFe 2 O 4 (M-Co, Ni, Mn and Zn etc.) are the most interesting magnetic oxides due to their superior electrical, magnetic and optical properties 1-8 .Among the spinel ferrites, cobalt ferrite is an attractive candidate due to its significant properties such as high coercivity, high electrical resistivity, moderate saturation magnetization, large magnetocrystalline anisotropy (~4x10 6 ergs/cm 3 ), good chemical stability and high Curie temperature (793 K) 9-16 . It is of significant technological interests due to its potential applications in targeted drug delivery systems 17, 18 , microwave devices 19, 20 , sensors 21 , catalysis 22, 23 and magnetic recording applications 9, 24 etc. Recently, the doping of small amount of trivalent rare earth cations in spinel ferrite has emerged as a promising strategy to improve the magnetic and electrical properties. Moreover, these properties are governed by the antiferromagnetic super exchange interaction between Fe 3+ -Fe 3+ ions; introducing small amount of trivalent rare earth (RE) ions into the spinel ferrite lattices will also induce RE 3+ -Fe 3+ interactions 25-30 . It is well known that the intrinsic properties of the spinel ferrite nanoparticles depend on the chemical composition and preparative methods 31, 32 . Spinel ferrites are prepared using several methods s...

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Section: Fe-sem and Eds Analysissupporting

confidence: 92%

Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

2015

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“…The procedure therefore does not introduce misleading information. However, it should be noted that this statement only holds up for strong coupling responses if the 180° pulse during the t 1 evolution is nonselective . For 1 H spectra, this should usually not be an issue, but off‐resonance effects might need to be considered when applying this method to nuclei with broad chemical shift dispersions, such as 19 F.…”

Section: Resultsmentioning

confidence: 92%

“…In fact, this procedure is equivalent to summing the normally processed 2DJ spectrum with its F 1 inverse. It has been shown that, even when considering strong coupling responses, 2DJ spectra in a (J,δ)‐representation should always be symmetrical along the J = 0 axis both in terms of peak position and intensity, as long as J‐evolution is sampled in a single spin echo . The procedure therefore does not introduce misleading information.…”

Section: Resultsmentioning

confidence: 99%

“…In estradiol, this is the case for protons 7α and 7β, which are both coupled to 6α and 6β. In Figure a, it can be seen that responses from 7α and 7β are not distributed along a single F 1 trace, similar to what is described for ABX spin systems in non‐pure shifted 2DJ experiments …”

Section: Resultsmentioning

confidence: 99%

“…Second, a z‐filter does not retain the spin‐states of the 1 H coupling partners, meaning there is no one‐to‐one connection between coherences evolving during the 2DJ evolution period and the direct acquisition evolution period. This is of no practical consequence for weakly coupled spin systems, but leads to a loss of information when second order effects in the 2DJ due to strong coupling cannot be neglected …”

Section: Introductionmentioning

confidence: 99%

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Clean pure shift 2D J‐resolved spectroscopy

Sinnaeve

2017

Magnetic Reson in Chemistry

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2D J-resolved spectroscopy is one of the oldest and conceptually most elegant ways to separate homonuclear scalar couplings from chemical shift information. In practice, the classical experiment suffers from a number of complications that limits accuracy and resolution, including phasetwist lineshapes, strong coupling artifacts, and the need for shearing the spectrum by 45° to obtain a (J,δ)-representation. Here, a novel pure shift 2DJ experiment based on the TSE-PSYCHE experiment is reported that deals with all these issues. Previous experiments proposed z-filtration to avoid excessive artifacts caused by chunked pure shift acquisition. It will be shown that these artifacts can also easily be avoided by means of the Pell-Keeler method. As opposed to its z-filtered counterparts, the new experiment provides pure shift 2DJ spectra that are free of artifacts from pulse imperfections and minimize responses related to strong coupling. In this way, multiplet analysis becomes possible at maximal resolution and a minimum of spectral complications.

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A comparative study on the structural, magnetic and dielectric properties of magnesium substituted cobalt ferrites

Sarmah

Patra

Maji

et al. 2023

Ceramics International

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High-Temperature Magnetic Behaviour of 10 % Aluminium-Substituted Cobalt Ferrite

Cited by 6 publications

References 36 publications

Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Clean pure shift 2D J‐resolved spectroscopy

A comparative study on the structural, magnetic and dielectric properties of magnesium substituted cobalt ferrites

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High-Temperature Magnetic Behaviour of 10 % Aluminium-Substituted Cobalt Ferrite

Cited by 6 publications

References 36 publications

Impact of Gd3+substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Impact of Gd3+substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Clean pure shift 2D J‐resolved spectroscopy

A comparative study on the structural, magnetic and dielectric properties of magnesium substituted cobalt ferrites

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Product

Resources

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Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Impact of Gd³⁺substitution on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles