Magnetic and catalytic properties of Cu-substituted SrFe12O19 synthesized by tartrate-gel method

Anantharamaiah, P.N.; Chandra, Niko; Shashanka, H.M.; Kumar, Rajeev; Sahoo, Balaram

doi:10.1016/j.apt.2020.04.004

Cited by 43 publications

(12 citation statements)

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“…It is well-known that spinel ferrite systems demonstrate two prominent fundamental absorption bands in the wavenumber region below 1000 cm –1 and emanate from the different metal ions located in the two crystallographic sites (tetrahedral and octahedral) of the spinel ferrites. , The absorption band situated at a lower wavenumber (∼408 cm –1 ), designated as ν 1 , is contributed by the metal–oxygen (M–O) intrinsic stretching vibration in the octahedral unit (MO 6 ), whereas the higher wavenumber (∼567 cm –1 ), designated as ν 2 , is attributed to the metal–oxygen (M–O) intrinsic stretching vibration in the tetrahedral unit (MO 4 ). The higher stretching frequency of the MO 4 unit is mainly due to the shorter M–O bond length as compared to that of M–O bond length of the MO 6 unit. , The frequencies of the absorption bands obtained for the parent compound (NFO) are in accordance with the reported values in the literature . The values of the absorbance bands of all of the samples are listed in Table .…”

Section: Resultssupporting

confidence: 86%

“…The higher stretching frequency of the MO 4 unit is mainly due to the shorter M−O bond length as compared to that of M−O bond length of the MO 6 unit. 36,37 The frequencies of the absorption bands The Journal of Physical Chemistry C obtained for the parent compound (NFO) are in accordance with the reported values in the literature. 38 The values of the absorbance bands of all of the samples are listed in Table 3.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

et al. 2022

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We report on the tunable dielectric properties achieved in cation-substituted nickel ferrite (NiFe 2 O 4 ; NFO) by selectively engineering the crystallographic site occupation of the dopant cation in the NFO ceramics. The NFO, Mg-substituted NFO (NiMg 0.2 Fe 1.8 O 4 ; NMFO), and In-substituted NFO (NiIn 0.2 Fe 1.8 O 4 ; NIFO) nanocrystals were synthesized by employing a tartrate-gel chemical route, followed by calcination at 500 °C. High-resolution transmission electron microscopy (HRTEM) analyses indicate the crystal quality of NFO, NMFO, and NIFO nanomaterials. The HRTEM data revealed that all of the ferrite materials were nanocrystalline with sizes in the range of 15−25 nm. Coupled with HRTEM analyses, X-ray diffraction analyses indicate the formation of single-phase spinel-structured NFO, NMFO, and NIFO materials without any detectable impurities. Chemical analysis performed using Mossbauer spectroscopy indicates that Mg 2+ occupies the octahedral site, while In 3+ preferably occupies the tetrahedral site of the spinel-structured NFO. The Fourier transform infrared (FTIR) absorption bands corresponding to metal−oxygen (M−O) intrinsic stretching vibration in the octahedral unit (MO 6 ) and the tetrahedral unit (MO 4 ), respectively, were noted in all of the samples. However, the trend in the frequency shift of these bands in Mg-and In-substituted NFO materials is different due to the occupation of different sites of Mg and In as confirmed by Mossbauer studies. The electronic structure and chemical valence state analysis using X-ray photoelectron spectroscopy (XPS) corroborates with chemical bonding analyses performed by FTIR and cation distribution evaluation carried out by Mossbauer spectroscopy. The energy-dispersive X-ray spectrometry (EDS) data, in addition to XPS and FTIR analyses, further validate the formation of uniform and chemically homogeneous samples. The corresponding cation distribution revealed from Mossbauer studies correlates with the variation of dielectric properties of the doped NFO samples with respect to intrinsic NFO. At room temperature, the dielectric constant (ε) of NFO and NMFO is found to be nearly the same and constant over a wide range of frequencies. However, in NIFO, ε decreases with the applied frequency. The differences are attributed to the size effect and site preference of dopants (Mg 2+ and In 3+ ). Irrespective of the dopants, an increase in the temperature enhances the dielectric constant, which is due to an increase in the number of free charge carriers. A thermally activated electrical conduction mechanism was operative in NFO, NMFO, and NIFO materials. The activation energies for NFO, NFMO, and NIFO were 18.84, 34.48, and 57.14 meV, respectively. The enhanced dipolar effect of In 3+ at the tetrahedral site compared to Mg 2+ at the octahedral site may be the origin of the relatively higher value of activation energy in NIFO compared to intrinsic and Mg-substituted NFO.

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Section: Resultssupporting

confidence: 86%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

et al. 2022

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“…It has many vital features including magnetic and electrical duality, high stability, and super-paramagnetic appearance. Owing to these critical features, spinel ferrites can be employed in different areas such as in sensing units, microwave absorbing devices, communication antennas, memory storage chips, medical diagnostics and imaging, photocatalysis, magnetic switching devices, and biotreatments [1][2][3][4][5] and as catalysts and magneto-rheological fluids.…”

Section: Introductionmentioning

confidence: 99%

Cation distribution, magnetic and hyperfine interaction studies of Ni–Zn spinel ferrites: role of Jahn Teller ion (Cu²⁺) substitution

et al. 2020

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“…Al 3+ is a non-magnetic trivalent cation that can be used for substituting isovalent Fe 3+ in SFO. It has been inferred from our previous studies reported in ref ( 47 ) that the catalytic activity more or less remains the same irrespective of dopant concentrations. Hence, we have considered a specific composition of Al-substituted strontium hexaferrite (SrFe 11.5 Al 0.5 O 19 ).…”

Section: Introductionmentioning

confidence: 58%

“…On the other hand, based on our previous work on magnetic and electronic materials, , we recognize that tailoring the materials’ structure and controlled phase in nanostructured materials can provide opportunities to design inexpensive nanomaterials for the desired applications. Furthermore, most recently, we demonstrated that the surface/interface magnetic properties can be tailored and have made successful attempts to derive catalytic properties in Cu-substituted strontium hexaferrites synthesized using a tartrate-gel method. , Therefore, in the present study, Al is chosen for the substitution in place of Fe in SrFe 12 O 19 and evaluated its activity toward the nitrophenol reduction reaction. Al 3+ is a non-magnetic trivalent cation that can be used for substituting isovalent Fe 3+ in SFO.…”

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confidence: 99%

Aluminum Doping and Nanostructuring Enabled Designing of Magnetically Recoverable Hexaferrite Catalysts

et al. 2022

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We demonstrate an approach based on substituting a magnetic cation with a carefully chosen isovalent non-magnetic cation to derive catalytic activity from otherwise catalytically inactive magnetic materials. Using the model system considered, the results illustratively present that the catalytically inactive but highly magnetic strontium hexaferrite (SrFe 12 O 19 ; SFO) system can be transformed into a catalytically active system by simply replacing some of the magnetic cation Fe 3+ by a non-magnetic cation Al 3+ in the octahedral coordination environment in the SFO nanocrystals. The intrinsic SFO and Al-doped SrFe 12 O 19 (SrFe 11.5 Al 0.5 O 19 ; Al–SFO) nanomaterials were synthesized using a simple, eco-friendly tartrate-gel technique, followed by thermal annealing at 850 °C for 2 h. The SFO and Al–SFO were thoroughly characterized for their structure, phase, morphology, chemical bonding, and magnetic characteristics using X-ray diffraction, Fourier-transform infrared spectroscopy, and vibrating sample magnetometry techniques. Catalytic performance evaluated toward 4-nitrophenol, which is the toxic contaminant at pharmaceutical industries, reduction reaction using NaBH 4 (mild reducing agent), the Al-doped SFO samples exhibit a reasonably good performance compared to intrinsic SFO. The results indicate that the catalytic activity of Al–SFO is due to Al-ions occupying the octahedral sites of the hexaferrite lattice; as these sites are on the surface of the catalyst, they facilitate electron transfer. Furthermore, surface/interface characteristics of nanocrystalline Al–SFO coupled with magnetic properties facilitate the catalyst recovery by simple, inexpensive methods while readily allowing the reusability. Moreover, the activity remains the same even after five successive cycles of experiments. Deriving the catalytic activity from otherwise inactive compounds as demonstrated in the optimized, engineered nanoarchitecture of Al-doped-Sr-hexaferrite may be useful in adopting the approach in exploring further options and designing inexpensive and recyclable catalytic materials for future energy and environmental technologies.

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Magnetic and catalytic properties of Cu-substituted SrFe12O19 synthesized by tartrate-gel method

Cited by 43 publications

References 43 publications

Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

Cation distribution, magnetic and hyperfine interaction studies of Ni–Zn spinel ferrites: role of Jahn Teller ion (Cu²⁺) substitution

Aluminum Doping and Nanostructuring Enabled Designing of Magnetically Recoverable Hexaferrite Catalysts

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Magnetic and catalytic properties of Cu-substituted SrFe12O19 synthesized by tartrate-gel method

Cited by 43 publications

References 43 publications

Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

Tunable Dielectric Properties of Nickel Ferrite Derived via Crystallographic Site Preferential Cation Substitution

Cation distribution, magnetic and hyperfine interaction studies of Ni–Zn spinel ferrites: role of Jahn Teller ion (Cu2+) substitution

Aluminum Doping and Nanostructuring Enabled Designing of Magnetically Recoverable Hexaferrite Catalysts

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Cation distribution, magnetic and hyperfine interaction studies of Ni–Zn spinel ferrites: role of Jahn Teller ion (Cu²⁺) substitution