Sol–gel synthesis and characterization of single-phase CoLa_xFe_2−xO₄ferrite nanoparticles dispersed in a SiO₂matrix

Abstract

Single-phase CoLaxFe2−xO4 (x = 0, 0.05, 0.10, 0.15, 0.20) nanoparticles dispersed in a SiO2 (30 wt%) matrix were synthesized by a sol–gel method.

Crystal strain, chemical bonding, magnetic and magnetostrictive properties of erbium (Er3+) ion substituted cobalt-rich ferrite (Co1.1Fe1.9−xErxO4)

“…The results are in good agreement with the reports available for rare earth dopants in CFO. [10][11][12][13][14][15]20 In order to gain further understanding, analysis of the XRD data was made to determine the crystallite size and strain developed in the samples. Such analysis is carried out using the full width at half maximum (FWHM) of the XRD peaks with maximum intensity.…”

“…On the other hand, 'increasing lattice constant coupled with induced strain' with Er 3+ content in CFEO, as noted in the present work, has been supported by and/or in agreement with reports available in the literature. [10][11][12][13][14][15]20,[28][29][30] Furthermore, the variation of cation distribution between the tetrahedral and octahedral sites gives the compressive strain due to the variation of ionic size of the two cations. Generally, in a spinel solid solutions within the miscibility range, a linear change in the lattice constant with concentration of components is observed as per Vegard's law.…”

“…Furthermore, the partial replacement of Fe 3+ in spinel structure, by rare earth ion or transition metal ion with large ionic radius leads to the structural distortion and hence induces the lattice strain which signicantly modies the electrical and magnetic properties. [9][10][11][12][13][14][15][16] The partial substitution of rare earth ions i.e., the 4f element series, for Fe 3+ in Co 1.1 Fe 1.9 O 4 , is promising to manipulate the magnetic properties. A rare earth ion possesses a variety of magnetic properties, 17 for example: (i) Er 3+ shows the magnetic moment z 7 m B (experimentally) at low temperature i.e.…”

“…18 Therefore, introducing the trivalent rare earth (RE) cations into the inverse ferrite lattice will also induce RE 3+ -Fe 3+ interactions, which could modify the corresponding magnetic properties. 2,[10][11][12][13][14][15] In the present work, erbium (Er) substituted cobalt rich CFO (i.e. Co 1.1 Fe 1.9Àx Er x O 4 ; referred to cobalt rich CFEO hereaer) synthesized by sol gel auto combustion method.…”

“…Erbium ion substituted cobalt ferrites are generally of great interest because Er 3+ ions possesses a decisive inuence on the structural and magnetic properties when compared to other rare earth ions. [10][11][12][13][14][15] Furthermore, even though Er 3+ is nonmagnetic at room temperature, the substitution of Er 3+ for Fe 3+ in CFO shows signicant saturation magnetization, which is extremely useful to maintain the magnetic hysteresis as well as a higher value of magnetic susceptibility desired for magnetic recording applications. 14,15,19 Also, there exists some controversy in terms of the composition-crystal structure in CFEO as a function of Er content.…”