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In this study, erbium-substituted Zn nanoferrites were synthesized by a simple coprecipitation method. The effect of pH on various physical parameters of erbium-substituted Zn nanoferrites was studied. The synthesized ferrite nanoparticles were characterized by XRD, FTIR, and SEM techniques and dielectric measurements. The gravimetric analysis showed the annealing temperature of these ferrites up to 700 °C. The result of XRD revealed the crystal structures of zinc nanoferrites. The FTIR spectra showed the weaker absorption peak due to Er–O stretching vibrations in zinc nanoferrites at pH 11. The SEM analysis showed that synthesized erbium-substituted Zn nanoferrites have a spherical shape with a size range from 42 to 46 nm. Dielectric properties exposed the typical semiconductor behavior of the erbium-substituted Zn nanoferrites. The electric constant at low pH was due to Fe+2 dielectric losses that dominated the sum of intrinsic and extrinsic loss. Increased in dielectric loss is associated with random crystallite orientation and impurities. The ZnFe2O4 nanoparticles with a decrease in dielectric loss revealed the crystallite orientation at pH 8 and 11. Tangent loss revealed the conductivity at higher pH 11 with a decrease in tangent loss. [ABSTRACT FROM AUTHOR]

In this study, optimized micro-emulsion route was utilised to synthesize the Cr-substituted MnFe 2 O 4 nanoparticles. Transition metal Cr3+ cations were used to replace the Fe3+ ions because the Cr3+ ions have compatible ionic radii and are non-magnetic in nature. Further, they have the same electronic configuration, which is the primary requirement for the substitution philosophy. Cr3+ (x) contents were in the range 0 ≤ x ≥ 0.16. All derivative of manganese ferrite nanoparticles were annealed at 400 °C. The annealing at the required temperature was carried out for 4 hours under vacuum. Structural information was collected via X-ray diffraction (XRD) analysis and Fourier transform infra-red (FTIR) spectroscopy. Both XRD and FTIR confirmed FCC structure of all compositions of Cr x MnFe 2- x O 4 nanoparticles. Various other physical parameters like lattice constant, cell volume, X-ray density, crystallite size were determined from obtained XRD data. Quantitative measurement of both divalent (Mn2+) and trivalent (Fe3+ and Cr3+) transition metal cations was calculated. FTIR spectral investigation was done to confirm the two typical bands corresponding to metal-oxygen vibrations present at A-sites and B-sites. After structural and spectral investigations, the electrical and dielectric properties were studied in detail for utilization of these ferrites for practical applications. Both electrical and dielectric properties were found in agreement with each other. The dielectric properties were carried out in frequency range 1 × 106 Hz to 3 × 109 Hz. In general, the both electrical and dielectric parameters were largely affected by Cr-substitution in MnFe 2 O 4 nanoparticles. [ABSTRACT FROM AUTHOR]

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]

In this work, fabrication of Gd3+ substituted nickel spinel ferrite (NiGd x Fe 2-x O 4) nanoparticles was carried out via co-precipitation route. X-ray powder diffraction (XRD) confirmed the spinel cubic structure of NiGd x Fe 2-x O 4 nanoparticles. XRD data also facilitated to determine the divalent and trivalent metal cations distribution at both A and B sites of the ferrite lattice. Site radii, hopping and bond lengths were also calculated from XRD data. The spectral studies elucidated the formation of cubic spinel ferrite structure as well as stretching vibrations of M–O (metal–oxygen) bond at A and B sites of ferrites, represented by two major bands υ 1 and υ 2 respectively. FESEM analysis confirmed the irregular morphology of NiGd x Fe 2-x O 4 nanoparticles. EDX spectrographs estimated the elemental compositions. The dielectric attributes were explained on the basis of the Debye-relaxation theory and Koop's phenomenological model. At higher applied frequencies (AC) no prominent dielectric loss was observed. Magnetic parameter variations can be attributed to the substitution of the rare earth cations having larger ionic radii as compared to the radii of Fe3+ ions. Moreover, spin canting, magneto-crystalline anisotropy and exchange energy of electrons also helped in magnetic evaluation. Due to small coercivity values NiGd x Fe 2-x O 4 nanoparticles can be employed significantly in high-frequency data storage devices. [ABSTRACT FROM AUTHOR]

Polycrystalline Er x Ni 0.8 Zn 0·2 Fe 2-x O 4 nanoparticles were synthesized using wet chemical route. Powder x-ray diffraction (XRD) data was utilized to observe the structural parameters. The cubic crystalline structure with the second phase was obtained from XRD patterns. Two significant absorption bands (between 700 and 400 cm−1) at the tetrahedral and octahedral sites were studied from Fourier transform infrared spectroscopy (FTIR) that further confirmed the spinel structure of prepared ferrites. These are the main bands of spinel ferrites. After the structural explanation, the dielectric, electrical and magnetic parameters were studied in detail at room temperature. All of these parameters were affected by Er3+ substitution. The obtained results suggested the possible utilization of these soft ferrites in advanced technological applications such as the devices working at high frequencies, magnetic data recording, switching applications, etc. [ABSTRACT FROM AUTHOR]

The Erbium substituted manganese spinel ferrites were prepared via the microemulsion route. The average crystallite size varies from 10.21 to 17.41 nm, while the lattice constant observes to increase from 8.473 to 8.509 Å. X-ray density increases with the incorporation of Er3+ ions in manganese ferrites. The characteristic bands lie in the range of 410–560 cm−1 which confirms the cubic structure of synthesized ferrites. The band variation is evidence of the successful substituting of Er3+ ions in manganese spinel ferrites lattices. Bond lengths increase with the increase of Er3+ content. The dielectric constant, dielectric loss, and tan loss decrease as frequency and Erbium concentration increase. Scanning electron microscopy (SEM) micrographs reveal the decrease in grain size with Er3+ in manganese ferrites. The obtained results suggested that synthesized ferries can be potential candidates for high-frequency applications. [ABSTRACT FROM AUTHOR]