Dielectric, impedance, AC conductivity and low-temperature magnetic studies of Ce and Sm co-substituted nanocrystalline cobalt ferrite

Ahmad, Syed Ismail; Rauf, Abdul; Mohammed, Tasneem; Bahafi, Amal; Kumar, Deepak; Suresh, M. Buchi

doi:10.1016/j.jmmm.2019.165666

Cited by 63 publications

(16 citation statements)

References 37 publications

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“…In recent decades, the synthesis of nanostructured spinel ferrites with the general formula MFe 2 O 4 (where M = Co, Ni, Mg, Mn, etc.) has been investigated in order to improve their unique properties such as magneto-optical properties [ 1 , 2 , 3 ], catalytic properties [ 4 , 5 ], electrical resistivity [ 6 ], magneto-resistivity [ 7 ], biocompatibility [ 8 , 9 , 10 ], porosity [ 11 ], etc. The spinel ferrites have a cubic unit cell containing 56 atoms, where 32 of them are oxygen anions, and the other 24 atoms are metallic cations of which only eight occupy tetrahedral sites (A-site) while the other 16 atoms occupy octahedral sites (B-site) [ 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method

et al. 2022

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In recent years, cobalt ferrite has attracted considerable attention due to its unique physical properties. The present study aimed to produce cobalt ferrite magnetic nanoparticles doped with zinc and vanadium using the sol-gel auto-combustion method. For this purpose, Co1-xZnxFe2-yVyO4 (where x = 0.0, 0.1, 0.2, 0.5 and y = 0.00, 0.05, 0.15, 0.25) precursors were calcined at 800 °C for 3h. The prepared samples were characterized with the X-ray diffraction (XRD) method in combination with Rietveld structure refinement, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometery (VSM). The XRD patterns confirmed the formation of crystalline spinel structure for all samples. However, the diffraction peaks of hematite and iron vanadium oxide phases were observed in the patterns of some doped samples. The average crystallite size for all the synthesized samples was found to be in the range of ~45–24 nm, implying that it decreased by simultaneously doping cobalt ferrite with Zn and V. The FT-IR spectrum confirmed the formation of the spinal structure of ferrite through the observed vibrational bands assigned to the tetrahedral (υ2) and octahedral (υ1) interstitial complexes in the spinel structure. The FE-SEM images showed that morphology, average grain size, and agglomeration of the synthesized powders were affected by doping, which was due to the interactions of the magnetic surface of nanoparticles. The VSM curves demonstrated that saturation magnetization and coercivity values changed in the range of 30–83 emu/g and from 27–913 Oe, respectively. These changes occurred due to the alteration in cation distribution in the spinel structure. This can be attributed to the change in superexchange interactions between magnetic ions by co-substitution of Zn and V ions in Cobalt ferrite and the changes in magnetocrystalline anisotropy.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method

et al. 2022

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“…ions with Er 3? ions is increasing the distance separating the magnetic ions, therefore, decreasing the strength of the tetrahedral and octahedral sites' ion super-exchange interactions [43]. The variation of saturation magnetization and magnetic coercivity concerning Er 3?…”

Section: Magnetic Propertiesmentioning

confidence: 98%

Low sintering effect on structural, electrical and magnetic properties of rare-earth metal ion Er3+-substituted nickel–zinc spinal ferrites

Sandeep

Rambabu

Kunja

et al. 2021

J Mater Sci: Mater Electron

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The nano-crystalline particles of erbium-substituted Ni-Zn ferrites with compositional formula Ni 0.7 Zn 0.3 Er x Fe 2-x O 4 (x = 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel autocombustion method using citric acid as a combustion agent. Samples were sintered at 500 k in a static air atmosphere. The structure and crystallite size were analysed from X-ray diffractogram and obtained data-revealing spinel phase formation in the range of nanometric crystallite size which is also confirmed through scanning electron microscopy. The crystallite size was found to decrease along with Er 3? dopant ranging from 26 to 15 nm. The lattice parameters were found to decrease with greater Erbium ion concentration. The spinel formation and the absence of the organic phase were monitored by using spectral analysis of Fourier transform infrared spectroscopy. Electrical and magnetic properties were analysed at room temperature. The dielectric and dielectric loss tangent studies at room temperature showed the high polarization effect at low frequencies and low at high frequencies. The AC conductivity studies were also confirmed and support the dielectric results and AC conductivity increased with frequency suggesting that the conduction mechanism is owing to small polaron hopping between cations. Various magnetic properties were investigated by using a vibrating sample magnetometer, the coercivity and magnetic remanence were decreasing with increasing Er 3? concentration, but the saturation magnetization results have fluctuated between 44 to 47 emu/g. The squareness ratio of all samples are ranging from 0.13 to 0.17 at room temperature which is less than 0.50 that indicates the multi-magnetic domain structure with uniaxial anisotropy.

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“…tan 𝛿 = 1 2𝜋𝑓𝑅 𝑝 𝐶 𝑝 (10) 𝜀 ˝= έ tan 𝛿 (11) σ 𝑎𝑐 = 2𝜋𝑓εₒ έ tan 𝛿 (12) Where 𝐶 is the capacitance of the pellet in farad, 𝑑 is the thickness of the pellet in meter, 𝐴 the cross-sectional area of the flat surface of the pellet, 𝜀ₒ is the constant of permittivity of free space, 𝑅 𝑝 is the equivalent parallel resistance, 𝐶 𝑝 is the equivalent parallel capacitance, and 𝑓 is the frequency.…”

Section: Dielectric Propertiesmentioning

confidence: 99%

“…The structural, magnetical, and electrical properties of cobalt ferrite are affected by a variety of characteristics in the spinel cobalt ferrite structure, including crystallite size, particle size, metal cation distribution among the lattice sites, and porosity [8]. The magnetic properties, such as saturation magnetization (𝑀 𝑆 ), remnant magnetization (𝑀 𝑟 ), and coercivity (𝐻 𝐶 ) cobalt ferrite, are strongly affected by the increase of calcination temperature [9,10]. Furthermore, the dielectric properties of cobalt ferrite are highly impacted by cation redistributions as the calcination temperature rises, making them appealing for high-frequency applications [10].…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic properties, such as saturation magnetization (𝑀 𝑆 ), remnant magnetization (𝑀 𝑟 ), and coercivity (𝐻 𝐶 ) cobalt ferrite, are strongly affected by the increase of calcination temperature [9,10]. Furthermore, the dielectric properties of cobalt ferrite are highly impacted by cation redistributions as the calcination temperature rises, making them appealing for high-frequency applications [10]. In this study, Co 0.8 Fe 2.2 O4 nanoparticles were synthesized using a sol-gel auto combustion method because it is simple to make, has high purity, requires little time, and has good uniformity at low temperatures [11].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Spinel Ferrite Co0.8Fe2.2O4 Nanoparticle

Jumaa¹,

Mubaraka²,

Mohammad³

2021

JUAPS

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Cobalt ferrite Co 0.8 Fe 2.2 O 4 nanoparticles were prepared using the sol-gel auto combustion process. The effects of calcination temperature on structural, magnetic, and electrical properties were studied. The cubic spinel phase fashioning of ferrite structure was confirmed using Fourier Transform-Infrared Spectroscopy (FT-IR) and X-ray Diffraction Patterns (XRD). The size of the formed crystallite of ferrite samples is ranged from 24.530 to 49.067 nm and it is found to be dependent on calcination. According to the images, which were taken by a Field Emission-Scanning Electron Microscope (FE-SEM), the particle size increases with raising the calcination temperature. Energy Dispersive Spectrum (EDS) was used to confirm the presence of Co, Fe, and O in all samples. A Vibrating Sample Magnetometer (VSM) was used to study the magnetic properties such as coercivity, saturation magnetization, and remanence field for the asburnt and calcined samples. All samples exhibited ferrimagnetic behavior. As the calcination temperature rises, saturation magnetization (𝑀 𝑠 ), remanent magnetization (𝑀 𝑟 ), and squareness ratio (𝑀 𝑟 / 𝑀 𝑠 ) increased. This behavior is related to the spin canting and disturbance in the surface spin. At room temperature, the dielectric loss factor (𝜀′′), dielectric loss angle (𝑡𝑎𝑛𝛿), dielectric constant (𝜀′), and the conductivity 𝜎 𝑎𝑐 of all samples were examined as a function of frequency using the LCR meter. The changes in dielectric properties have been characterized at frequencies ranged from 50Hz to 2MHz based on Koop's theory, Maxwell-Wagner polarization, and electron hopping. As frequency rose, all-dielectric properties exhibited natural behavior.

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Dielectric, impedance, AC conductivity and low-temperature magnetic studies of Ce and Sm co-substituted nanocrystalline cobalt ferrite

Cited by 63 publications

References 37 publications

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method

Low sintering effect on structural, electrical and magnetic properties of rare-earth metal ion Er3+-substituted nickel–zinc spinal ferrites

Synthesis and Characterization of Spinel Ferrite Co0.8Fe2.2O4 Nanoparticle

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