Abstract
In this study, the samples of the ZnFe2O4 (ZFO) spinel ferrites nanoparticles (SFNPs), Co0.5Ni0.5Ga0.01Gd0.01Fe1.98O4 (CNGaGdFO) SFNPs and (Co0.5Ni0.5Ga0.01Gd0.01Fe1.98O4)x/(ZnFe2O4)y (x:y = 1:1, 1:2, 1:3, 2:1, 3:1 and 4:1) (CNGaGdFO)x/(ZFO)y spinel ferrite nanocomposites (NC) have been synthesized by both sol-gel and Green pulsed laser ablation in liquid (PLAL) approaches. All products were characterized by X-ray powder diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), elemental mappings and energy dispersive X-ray spectroscopy (EDX). It was objected to tune the magnetic properties of a soft spinel ferrite material with a softer one by mixing them with different fractions. Some key findings are as follows. M-H investigations revealed the exhibition of ferrimagnetic phases for all synthesized samples (except ZnFe2O4) that were synthesized by sol-gel or PLAL methods at both 300 K and 10 K. ZnFe2O4 ferrite NPs exhibits almost paramagnetic feature at 300 K and glass-like phase at very low temperatures below 19.23 K. At RT analyses, maximum saturation magnetization (MS) of 66.53 emu/g belongs to nanocomposite samples that was synthesized by sol-gel method and x:y ratio of 1:3. At 10 K analyses, MS,max = 118.71 emu/g belongs to same nanocomposite samples with ratio of 1:3. Maximum coercivities are 625 Oe belonging to CNGaGdFO and 3564 Oe belonging to NC sample that was obtained by sol-gel route having the 3:1 ratio. Squareness ratio (SQRs = Mr/MS) of NC sample (sol-gel, 4:1 ratio) is 0.371 as maximum and other samples have much lower values until a minimum of 0.121 (laser, 3:1) assign the multi-domain wall structure for all samples at 300 K. At 10 K data, just CNGaGdFO has 0.495 SQR value assigning single domain nature. The maximum values of effective crystal anisotropy constant (Keff) are 5.92 × 104 Erg/g and 2.4 × 105 Erg/g belonging to CNGaGdFO at 300 K and 10 K, respectively. Further, this sample has an internal anisotropy field Ha of 1953 Oe as largest at 300 K. At 10 K another sample (sol-gel, 3:1 ratio) has Ha,max of 11138 Oe which can also be classified as a soft magnetic material similar to other samples. Briefly, most magnetic parameters of NCs that were synthesized by sol-gel route are stronger than magnetic parameters of the NCs that were synthesized by PLAL at both temperatures. Some NC samples were observed to have stronger magnetic data as compared to magnetic parameters of Co0.5Ni0.5Ga0.01Gd0.01Fe1.98O4 NPs at 10 K.
Highlights
Magnetic nano particles especially nano-sized spinal ferrites (NSFs) are promising magnetic materials due to their extensive applications in medicine, photocatalysis, microwave absorption and energy storage [1,2,3]
The samples synthesized using solid state reaction showed magnetic order whereas the samples prepared through citrate method exhibited super magnetic nature. These results show that the structural and magnetic properties of the nano ferrites depend mainly on the reactants, synthesis methods, initial concentration and thermal treatment
The samples of the ZFO NPs, CNGaGdFO NPs individually, and (CNGaGdFO)x /(ZFO)y (x:y = 1:1, 1:2, 1:3, 2:1, 3:1 and 4:1) NCs were produced by two ways, first was one-pot sol–gel auto-combustion and second was Green pulsed laser ablation in liquid (PLAL)
Summary
Magnetic nano particles especially nano-sized spinal ferrites (NSFs) are promising magnetic materials due to their extensive applications in medicine, photocatalysis, microwave absorption and energy storage [1,2,3]. The round brackets (A) represent tetrahedral interstitial sites and square brackets [B] correspond to larger octahedral sites. Both of these sites are occupied by cations with divalent ions occupying tetrahedral and trivalent ions occupying octahedral sites [4]. The magnetic moments of the cations occupying octahedral lattice sites are oriented in the same direction. Whereas the magnetic moment of the cations at tetrahedral sites are oriented anti parallel to that of the cations at octahedral sites. The resultant of these two magnetic moments give rise to the net magnetization in spinel ferrites [5]
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