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Abstract New yttrium substituted manganese ferrite (MnY x Fe 2- x O 4) nanoparticles (NPs) were prepared by low cost reverse micelle micro-emulsion method by utilizing cheap raw materials like Paraffin, Triton X-100, and 1-butanol and corresponding metal salts. The Y3+content (x) range was kept 0 ≤ x ≤ 0.16. Thermogravimetric analysis (TGA) of un-annealed precipitates was carried out to probe the phase formation temperature. The annealing of precipitates of all compositions of MnY x Fe 2- x O 4 nanoparticles was carried at 400 °C for 4 h (h). The annealing was carried out under vacuum to control the oxidation of manganese. The effect of Y3+ cations on structural, spectral and dielectric properties was investigated by X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy and impedance analyzer measurements at room temperature. XRD patterns confirmed the formation of MnFe 2 O 4 and its derivatives with yttrium. Site radii and bond lengths were calculated from XRD data. FTIR spectra confirmed the tetrahedral (A) and octahedral (B) sites in all compositions of MnY x Fe 2- x O 4 nanoparticles, which is characteristic of spinel ferrites having FCC (face centered cubic) structure. Scanning electron microscopic (SEM) analysis confirmed the spherical morphology of ferrite particles. Dielectric parameters analysis in the frequency range from 1 × 106 Hz to 3 × 109 Hz suggested that these ferrite particles may find their potential applications in high frequency devices fabrication. [ABSTRACT FROM AUTHOR]

Abstract In this work erbium (Er3+) substituted cobalt zinc ferrite having general formula Co 0.70 Zn 0.30 Er x Fe 2-x O 4 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) were fabricated using micro-emulsion technique. The substitution of Er was done for the purpose of tuning the optical band gap. Er+3 substituted nanoparticles were annealed at 700 °C for 7 h. A typical composition of Co 0.70 Zn 0.30 Er x Fe 2-x O 4 was utilized to make the nanocomposites material with reduced graphene oxide (rGO), that was prepared by facile chemical route. The main purpose of graphene was to enhance the conductivity of ferrite particles. All these ferrite particles and a composite were characterized by X-rays diffraction (XRD), UV–Visible spectroscopy and SEM for structural elucidation and morphology studies. Single phase spinel structure was confirmed by XRD analysis and crystallized size calculated by Scherer formula was found in the range 35–60 nm. SEM confirmed the well dispersed ferrite particles among graphene sheets. All the Er-substituted ferrite particles were subjected to dielectric parameters study. One typical composition of Co 0.70 Zn 0.30 Er x Fe 2-x O 4 particles and its composites with rGO were utilized for photocatalysis study using methylene blue as model organic compound in the presence of visible light. Current-voltage (I-V) measurements of ferrites nanoparticles and their composites with graphene were also studied. The results of all these techniques were agreed with each other and suggested the various potential applications of these nanoparticles. Highlights • Rare earth Er3+-substituted Cobalt-Zinc Nano-ferrites were prepared. • XRD confirmed the FCC structure of all compositions. • Graphene@ ferrite composites exhibited better photocatalytic properties. [ABSTRACT FROM AUTHOR]

In this article, we have reported an effective, rapid as well as economical Er3+ substituted Ni 0.4 Co 0.6 Fe 2 O 4 ferrite nanoparticles synthesized via surfactant-assisted co-precipitation route. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), dielectric properties, current-voltage (I–V) measurements, and vibrating sample magnetometry (VSM). XRD and FTIR confirmed the face-centered (FCC) spinel structure of all compositions of the synthesized spinel ferrite nanoparticles. The deviations in the lattice constant granted with the variation in size of the guest (Er3+) and host (Fe3+) cations. These ferrites were also subjected for electrical, magnetic and dielectric investigations. I–V measurements showed that resistivity values decreased from 6.20 × 107 Ω cm to 0.03 × 107 Ω cm with the increased Er3+ contents. Saturation magnetization increased from 35.99 to 39.95 emu/g. This high value of saturation magnetization suggested the possible utilization of such ferrites for practical applications such as microwave and recording devices fabrication. Interestingly, the magnetic and dielectric properties of nickel-cobalt ferrite nanoparticles showed ample improvement upon Er3+ substitution. The results clearly indicate the potential of Er+3 substituted spinel ferrite particles in various advanced technological devices fabrication. [ABSTRACT FROM AUTHOR]

A multipurpose, environment-friendly, and effective catalyst for control of environmental contaminants is an enduring interest in recent years. In the present study, lanthanum substituted spinel ferrite (La x MnFe 2-x O 4) nanoparticles were synthesized using an eco-friendly, low cost-effective reverse-micelle synthesis strategy. Thermal analysis was done to annualize the annealing temperature of prepared precipitates. X-ray diffraction (XRD) study revealed the well-defined cubic spinel structure of La x MnFe 2-x O 4 with the presence of a very minute secondary phase by the introduction of La3+ ion. Fourier transform infrared spectroscopy (FTIR) study confirmed the M − O metal-oxygen bond stretching at tetrahedral and octahedral sites. Surface morphology analyzed by field emission scanning electron microscopy (FESEM) revealed the narrow size distribution having nanoparticles size of nearly 60 nm. From the bandgap study, an enhanced redshift of 2.40 eV directed its semiconductor photocatalysis behavior. The degradation efficiency of pristine MnFe 2 O 4 and La3+ ion substituted MnFe 2 O 4 material was investigated using a contaminant crystal violet dye. Higher degradation efficiency, kinetic investigation smart degradation mechanism, and simple recovery suggested that the newly designed La3+ ion substituted MnFe 2 O 4 photocatalytic material is best for environmental remediation. [ABSTRACT FROM AUTHOR]