Crystallographic and Magnetic Properties of Nickel Substituted Manganese Ferrites Synthesized by Sol-gel Method

Abstract

Nickel substituted manganese ferrites, Mn 1-x Ni x Fe 2 O 4 (0.0 ≤ x ≤ 0.6), were fabricated by sol-gel method. The effects of sintering and substitution on their crystallographic and magnetic properties were studied. X-ray diffractometry of Mn 0.6 Ni 0.4 Fe 2 O 4 ferrite sintered above 523 K indicated a spinel structure; particles increased in size with hotter sintering. The Mössbauer spectrum of this ferrite sintered at 523 K could be fitted as a single quadrupole doublet, indicative of a superparamagnetic phase. Sintering at 573 K led to spectrum fitted as the superposition of two Zeeman sextets and a single quadrupole doublet, indicating both ferrimagnetic and paramagnetic phase. Sintering at 673 K and at 773 K led to spectra fitted as two Zeeman sextets due to a ferrimagnetic phase. The saturation magnetization and the coercivity of Mn 0.6 Ni 0.4 Fe 2 O 4 ferrite sintered at 773 K were 53.05 emu/g and 142.08 Oe. In Mn 1-x Ni x Fe 2 O 4 (0.0 ≤ x ≤ 0.6) ferrites, sintering of any composition at 773 K led to a single spinel structure. Increased Ni substitution decreased the ferrites' lattice constants and increased their particle sizes. The Mössbauer spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and the octahedral sites of the Fe 3+ ions. The variations of saturation magnetization and coercivity with changing Ni content could be explained using the changes of particle size.

Structural and Magnetic Properties of Ni0.6Zn0.4Fe2O4Ferrite Prepared by Solid State Reaction and Sol-gel

“…on the octahedral sites, NZ-solid should possess higher magnetization as compared to NZ-sol-gel [16]. However, our observation revealed a different result as shown in Fig.…”

Effects of Solution Concentration on the Structural and Magnetic Properties of Ni0.5Zn0.5Fe2O4Ferrite Nanoparticles Prepared by Sol-gel

“…For concentration of 0.75 M, the reaction rates may be too high to allow complete reaction and optimum bonding of the atoms, resulting in a degraded crystallinity and smaller particle sizes. Since the magnetization of the ferrite materials is mainly determined by the interactions between Fe 3+ on the A sites and Fe 3+ on the B sites, better crystallinity improves magnetization [12], which explains the increased saturation magnetization up to 0.5 M. On the other hand, smaller particles prepared with 0.75 M possess higher surface energy and surface tension, which could results in reduced magnetization [7]. The coercivity measures the resistance of a ferromagnetic material to becoming demagnetized, and usually, the nanoparticles show larger coercivity than the corresponding bulk materials, especially when the particle size is close to the single domain limit.…”

“…As compared to other processes, sol-gel has the advantages of simple procedures and the prepared nanoparticles usually have a high degree of crystallinity with a uniform microstructure and better magnetic behaviors [7]. The reaction parameters of the sol-gel process, for example, the type of precursors used, reaction temperature and pH value, etc., have been reported to have direct effects on the properties of fabricated ferrite nanoparticles [7][8][9][10][11][12]. In this work, we prepared NiZn ferrite nanoparticles through the sol-gel method by dissolving the corresponding metal nitrates in 2-methoxythanol.…”