Self-ignited high temperature synthesis and enhanced super-exchange interactions of Ho³⁺–Mn²⁺–Fe³⁺–O²⁻ferromagnetic nanoparticles

Abstract

The present work is focused on the effect of Fe(3+) replacement by rare earth-Ho(3+) ions and their influence on the properties of MnFe2O4 ferrite. The Ho(3+) substituted MnFe2O4 ferrite samples with chemical formula MnHoxFe2-xO4 were synthesized where substitution concentration of Ho(3+) was 0.0, 0.05, 0.1 and 0.15. The samples were synthesized by the self-ignited sol-gel method using the nitrates of the respective elements. Powder X-ray diffraction, transmission electron microscopy, infrared spectroscopy, vibrating sample magnetometer (VSM) and electrical measurements were employed to characterize the structural, magnetic and electrical properties of these ferrite nanoparticles. The cations distribution between the tetrahedral (A-site) and octahedral sites (B-site) has been estimated by XRD analysis. It is found that substitution of Ho(3+) ions favorably influenced the magnetic and electrical properties. Magnetic measurements were carried out at 77 and 300 K. Saturation magnetization and coercivity increased from 54.57 to 71.6 emu g(-1) and 172 to 766 Oe, respectively, with increasing the Ho(3+) substitution. The change in magnetic properties may be explained with the increase of A-O-B (FeA(3+)-O(2-)-HoB(3+)) super exchange interactions and the anisotropy constant. The electrical properties show that the pure sample has lower resistivity with respect to any Ho(3+) doped one. The conduction mechanism is used to interpret electrical measurements. Results of the presently investigated samples with enhanced saturation magnetization, coercivity and remanence ratio indicate that the Ho(3+) doped MnFe2O4 nanoparticles can be a useful candidate for the application in high density recording media.

Crystal chemistry and single-phase synthesis of Gd3+substituted Co–Zn ferrite nanoparticles for enhanced magnetic properties

“…Furthermore, the increased value of H c could be related to the decrease in particle size with Gd 3+ substitution where demagnetization caused by domain rotation (single domain) requires higher energy compared to the movement of the domain walls (multidomain). 42 The temperature dependences of the magnetization, in eld cooled (FC) and zero eld cooled (ZFC) modes, were measured over a temperature range of 10 K to 375 K with the application of a 500 Oe eld (Fig. 9).…”

Magneto-optical properties of Mn3+ substituted Fe3O4 nanoparticles

“…Manganese ferrite nanoparticles with spinel structure are important for technological applications owing to their soft magnetic properties. They are widely used for microwave, inductance, magnetic recording media, electronic devices, magnetic storage devices, magnetic contrast and agent applications due to its high electrical resistance and high magnetic permeability [18][19][20][21][22][23]. As a potential member of contrast agents in Magnetic Resonance Imaging (MRI), the superparamagnetic manganese ferrite (MnFe 2 O 4 ) NPs have been found to have a very large relaxivity and high magnetization owing to their large magnetic spin magnitude [24,25].…”

“…As a potential member of contrast agents in Magnetic Resonance Imaging (MRI), the superparamagnetic manganese ferrite (MnFe 2 O 4 ) NPs have been found to have a very large relaxivity and high magnetization owing to their large magnetic spin magnitude [24,25]. There are several methods employed to synthesize manganese ferrite such as solid-state reaction, high-temperature solution phase reaction of metal acetylacetonates, coprecipitation method and self-ignited high temperature synthesis [23,[26][27][28][29][30]. Even polyol techniques provide many advantages such as control over the particle size and shape, and mass production, which is main factor for technological applications.…”

DC Electrical Resistivity, Dielectric, and Magnetic Studies of Rare‐Earth (Ho3+) Substituted Nano‐Sized CoFe2O4

“…Research is being done on rare earth (RE) substituted ferrites nowadays in order to enhance the electrical, dielectric, magnetic, and magnetoelectric properties . Theoretical as well as experimental findings indicated the exchange interactions between the spinel ferrites and rare earth (RE) transition metal (4f–3d) elements has been a flourishing research activity in recent decades . This is due to the larger ionic radii, the presence of unpaired 4f electrons and magnetocrystalline anisotropy that is instigated by 4f–3d coupling due to exchange interaction .…”

“…[16][17][18][19][20][21][22][23][24] Theoretical as well as experimental findings indicated the exchange interactions between the spinel ferrites and rare earth (RE) transition metal (4f-3d) elements has been a flourishing research activity in recent decades. [24][25][26][27] This is due to the larger ionic radii, the presence of unpaired 4f electrons and magnetocrystalline anisotropy that is instigated by 4f-3d coupling due to exchange interaction. [27][28] Literature report on substitution of Ho 3þ ions in CFO which reveal enhanced saturation magnetization and coercivity with the rare earth Ho 3þ substitution which may probably be due to the larger magnetic moment of Ho 3þ ions and enhanced exchange interaction.…”