Study of structural, magnetic properties and bandgap of spinel Co1−xFe2+xO4 ferrite

et al. 2021

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We report sol gel auto-combustion synthesized CoCr x Fe 2-x O 4 (x = 0.0 − 1.0) spinel ferrites, and use x-ray diffraction 'XRD', magnetic measurements, and Mössbauer spectroscopy to study the effect of Cr-content on their structural properties, magnetic properties, and correlation between them. Formation of single-phase nono spinel ferrite (grain size: 18.1 -46.6 nm), is confirmed by XRD. Results show that with increasing Cr-content, lattice parameter decreases, and Cr 3+ ions remain more populated on B-site, whereas Co 2+ ions remains almost equally populated on both A, B site, show lower disorder, and modification of A-O − A, B-O − B, A-O − B super-exchange interaction. For Cr-content ≥ 0.75, Mössbauer measurements show presence of a non-magnetic doublet, and isomer shift values confirm that Fe has 3 + oxidation state. Observed structural changes, lead to reduction of saturation magnetization, coercivity.

Section: Magnetic Behaviormentioning

confidence: 61%

57Fe Mössbauer study of CoCrxFe2-xO4 nano ferrite

Tiwari¹,

Verma²,

et al. 2021

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“…Preparation of Co1-xFe2+xO4 (x = 0.0 0.8) spinel nano ferrites was done by sol-gel autocombustion method, utilizing AR grade nitrate-citrate precursors, During synthesis solution pH was maintained at 7, by adding Ammonia solution [NH4OH], and metal salt to citric acid ratio was kept as 1:1. More details on synthesis can be seen in [14]. Prepared dry gel samples were annealed in muffle furnace (in air) at 600 o C for 3 hours, and were used for characterization.…”

Section: Materials Synthesis Materials Characterization and Data Anal...mentioning

confidence: 99%

“…-sol gel [6,7], hydrothermal [8], solid state reaction [9], coprecipitation [10] etc., ii) compositional variation [6,7,11], and iii) thermal annealing /or no thermal annealing [12], ion irradiation [13] etc. Literature also reports tuning of bandgap, structural, magnetic properties [14,15,16]. CoFe2O4 has inverse spinel structure, and Fe 3+ ions are dispersed nearly equally on A (tetrahedral), B (octahedral) site, while Co 2+ ions on B site.…”

Section: Introductionmentioning

confidence: 99%

“…Co0.8Fe2.2O4 system (here excess Fe is 0.2), reported in [22] shows magnetic field induced phase transition [23]. Kane et el [14] report the study of bandgap, magnetic, structural, properties, in dry gel Co1 xFe2+xO4 (x = 0.0-0.8) spinel nano ferrites, where excess Fe-content has considerable effect on aforementioned properties. In spinel ferrites, compositional variation, thermal annealing etc.…”

Section: Introductionmentioning

confidence: 99%

“…In spinel ferrites, compositional variation, thermal annealing etc. is known to affect structural, magnetic properties, bandgap e. g. - [6,7,11,14,24] etc. So study of effect of thermal annealing in Co1 xFe2+xO4(x = 0.0-0.8) spinel ferrite, would be interesting to obtain the information on thermal annealing induced changes in structural, magnetic properties, bandgap and correlation between them.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of thermally treated Co_1-xFe_2+xO₄ (x = 0.0 –0.8) spinel nano ferrite

Parmar

Verma

IOP Conf. Ser.: Mater. Sci. Eng.

et al. 2022

We report the effect of surplus-Fe-content, and thermal annealing on the properties of sol gel auto-combustion synthesized Co1–xFe2+xO4 (x = 0.0–0.8) spinel ferrites. X-ray diffraction (XRD), magnetic measurements, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–visible (UV–Vis) are used to monitor the effect of excess Fe-content, and thermal annealing dependence of properties, and correlation among them. XRD validates presence of spinel nanoferrite (31.54 – 44.89 nm) phase, minor presence of α-Fe2O3 phase was also detected. Results reveal that variation of Fe-content leads to: i) variation of lattice-parameter, re-distribution of Fe3+. Co2+ ions on A, B-site, ii) alteration of inversion degree, disorder, iii) modification of saturation magnetization due to spin disorder at surface, iv) variation of coercivity, and related grain size imply that studied ferrites are in single-multi domain overlap regions, while squareness-ratio indicates variation of inter-grain interaction, isotropic behaviour of multi-domain particles; iv) fine-tuning of bandgap (1.35 – 1.5 eV) via changes in cationic-distribution and lattice-parameter, v) variation of Debye temperature, suggests modification of lattice vibrations. Current work implies strong correlation between bandgap magnetic, structural properties.

Structural, Mössbauer and magnetic study of Co1-xZnxFe2O4 (x = 0.0 − 0.56) nano ferrites

Kane¹,

Verma²,

et al. 2022

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We report on the synthesis of spinel Co1-xZnxFe2O4 (x=0.00.56) ferrites by sol-gel auto-combustion method. Xray diffraction 'XRD', magnetic measurements were used to study compositionaldependence of structural, magnetic properties, connection among them. Mössbauer spectroscopy was used to identify non-magnetic-phase, its effect on magnetic properties. Single-phased nano spinel-ferrite formation is confirmed by XRD. Increasing Zn-content leads to structural modifications such as decrease of lattice parameter, grain diameter DW-H, alteration of inversion parameter, disorder, tensile-strain, dislocation density, variation of A-O-B, A-O-A, B-O-B superexchange-interaction and canting angles. Cationic distribution suggests that Fe 3+ , Co 2+ ions reside on both A, Bsites, and with increasing Zn-content, B-site population of Fe 3+ , Zn 2+ ions increases; while that of Co 2+ ions decreases. Saturation magnetization shows noticeable dependence on canting angle suggests that the magnetization in the studied samples is described by Yafet-Kittel three-sub-lattice model. Coercivity Hc values are consistent with anisotropy, and its dependence on DW-H suggests that the studied samples are in overlap-region between multiple-domains/single-domain. Reduced-remanence indicate the variation of inter-grain magnetostatic-interaction, isotropic-behavior of multi-domain particles. Observed broad peaks in magnetization derivative with field suggest large-number of dislocations, more-uniform particle-size. Switching-fielddistribution proposes potential application of the studied x=0.0 sample in high density recording, and sample with x=0.56 in targeted drug delivery. Mössbauer measurements confirm three-magnetic-components corresponding to A,B-sites, Fe3+ ions in grain boundaries/surface, Fe has 3+ oxidation state, and growing paramagneticdoublet, alone does not explain the trend of Ms, suggesting that it is a collective-effect of structural-modification, presence of paramagnetic-doublet.