Investigations of lanthanum doping on magnetic properties of nano cobalt ferrites

Kumar, Pawan; Sharma, S. K.; Knobel, M.; Chand, Jagdish; Singh, M.

doi:10.1007/s10832-011-9649-4

Cited by 28 publications

(8 citation statements)

References 20 publications

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“…The total magnetization of cobalt ferrite is the difference between the magnetization of B and A sites, and consequently the magnetization is reduced at room temperature. 53 It is observed that for pure cobalt ferrite with a crystallite size of 46 nm, a M s value of 80 emu g À1 is found at 300 K, which is in good agreement with the reported value (76 emu g À1 ). 54 Moreover, the doping of Gd 3+ ions in cobalt ferrite monotonically decreases the value of the saturation magnetization from 80 to 53.8 emu g À1 when the crystallite size of the Gd 3+ doped cobalt ferrite decreases from 40 to 23 nm.…”

Section: Magnetic Studysupporting

confidence: 89%

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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: Magnetic Studysupporting

confidence: 89%

“…10 (a, b). The total magnetization of cobalt ferrite is the difference between the magnetization of B and A sites, and subsequently reduces the magnetization at room temperature 53 . The saturation magnetization (M s ), the coercivity (H c ) and the remanance magnetization (M r ) at 300 K and 10 K are given in Table 3.…”

Section: Fe-sem and Eds Analysismentioning

confidence: 99%

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

2015

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“…At first sight, the Raman spectra of our particles exhibit clearly broadened bands compared with bulk CoFe 2 O 4 . This feature is quite common in nanostructures (Yu et al, ; Tahar et al, ; Kumar et al, ). Moreover, the bands above 600 cm −1 , related to the two A 1g modes, are found to overlap, in accordance with previous works on nanocrystalline spinel ferrites (da Silva et al, ; Kumar et al, ).…”

Section: Resultsmentioning

confidence: 94%

“…A rapid overview of the relevant literature shows that chemically made (Co 1 − x Zn x )Fe 2 O 4 nanocrystalline solid solutions exhibit a maximal magnetization at x ranging between 0.4 and 0.5 (Sharifi and Shokrollahi, ; Tahar et al, ; Ghasemian et al, ; Tatarchuk et al, ). In the case of Co(Fe 1 − x Ln x )O 4 nanocrystalline solid solutions, the highest magnetization was obtained for Ln = Gd and x ~ 0.1, the solubility limit of Ln cations being of the same order (Tahar et al, ; Kumar et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of polyol‐made Gd³⁺‐substituted Co_0.6Zn_0.4Fe₂O₄ nanoparticles as high magnetization MRI negative contrast agents

Mnasri

Bentahar

Nowak

et al. 2019

J of Interdiscip Nanomed

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The structural, microstructural, and magnetic properties of~5-nm-sized Co 0.6 Zn 0.4 Fe 2-x Gd x O 4 nanoparticles were investigated in order to evaluate their capability to enhance the magnetic resonance imaging contrast as high magnetization agents. A focus was made on the solubility of Gd 3+ cations within the spinel lattice. By coupling X-ray diffraction to X-ray fluorescence spectroscopy, we demonstrated that only a limited fraction of Gd 3+ can substitute Fe 3+ ions into the whole crystal structure and does not exceed 6 at.-%. At this concentration, the room temperature (27°C) saturation magnetizations of the prepared superparamagnetic nanocrystals were found to be close to 80 emu g À1 .Coating these nanoparticles with hydrophilic dopamine ligands leads to the formation of 50-nm-sized clusters in water. As a consequence, relatively high r 2 /r 1 ratios of transverse to longitudinal proton relaxivities and high r 2 values were measured in the resulting colloids at physiological temperature (37°C) for an applied magnetic field of 1.41 T: 33 and 188 mM À1 sec À1 , respectively, for the richest system in gadolinium. Moreover, after incubation with healthy human model cells (fibroblasts) at doses as high as 10 μg mL À1 , they induce neither cellular death nor acute cellular damage making the engineered probes particularly valuable for negative magnetic resonance imaging contrasting.

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“…Moreover, the spinel ferrites have the resourceful magnetic and electrical properties among other ferrites. In particular, CoFe 2 O 4 has attracted considerable attention because of its structural, magnetic and electrical conductivity under a range of conditions [16][17][18][19] Furthermore, CoFe 2 O 4 possesses a partially inverse structure with a degree of inversion that depends on the method of preparation and heat treatment 20 21 CoFe 2 O 4 has a spinel crystal structure and crystallizes in a cubic close packed structure of oxygen ions, in which tetrahedral [A] and octahedral [B] sites are occupied by cations. At the same time, the magnetization, coercivity, permittivity and conductivity are greatly affected by the porosity, grain size and microstructure of the sample.…”

Section: Introductionmentioning

confidence: 99%

Yttrium-Doped Cobalt Nanoferrites Prepared by Sol–Gel Combustion Method and Its Characterization

Shobana¹,

Nam²,

Choe³

2013

j nanosci nanotechnol

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Ferrites are extremely important magnetic ceramics in the production of electronic components because they reduce the energy losses by the induced currents acting as electrical insulators. Similarly, the spinel-structured cobalt-based ferrites are promising materials for stress, torsion sensors and energy storage applications (anode materials in lithium batteries, fuel cells and solar cells). Therefore, many studies have focused on cobalt ferrites obtained using conventional techniques. Different sintering conditions, types and levels of substitution result in different microstructures and magnetostriction coefficients under a wide range of preparation conditions. Despite many attempts, there are no specific reports on the trivalent substitution of yttrium in cobalt ferrite to the best of our knowledge. In the present study, yttrium-doped cobalt ferrite was prepared with different concentrations to identify the crystallite size with respect to the yttrium concentration, temperature and changes in the structural and electrical properties. In addition, the resistance of the nanostructured yttrium-doped cobalt ferrites nanopowders was analyzed. The resistance was increased by the addition of yttrium to cobalt ferrites.

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Investigations of lanthanum doping on magnetic properties of nano cobalt ferrites

Cited by 28 publications

References 20 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

Evaluation of polyol‐made Gd³⁺‐substituted Co_0.6Zn_0.4Fe₂O₄ nanoparticles as high magnetization MRI negative contrast agents

Yttrium-Doped Cobalt Nanoferrites Prepared by Sol–Gel Combustion Method and Its Characterization

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Investigations of lanthanum doping on magnetic properties of nano cobalt ferrites

Cited by 28 publications

References 20 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

Evaluation of polyol‐made Gd3+‐substituted Co0.6Zn0.4Fe2O4 nanoparticles as high magnetization MRI negative contrast agents

Yttrium-Doped Cobalt Nanoferrites Prepared by Sol–Gel Combustion Method and Its Characterization

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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

Evaluation of polyol‐made Gd³⁺‐substituted Co_0.6Zn_0.4Fe₂O₄ nanoparticles as high magnetization MRI negative contrast agents