Effect of pH on Structural, Magnetic and FMR Properties of Hydrothermally Prepared Nano Ni Ferrite

Abstract

Nano nickel ferrite particles were prepared at pH values 1.5, 4, 7, 10, 13 by a hydrothermal method using metal chlorides and NaOH as an oxidant and solution basicity controller. There is a phase transition from hematite to spinel ferrite that begins when the pH reaches 4. The lowest crystallite size (4 nm) was associated with a highest lattice constant (8.345 Å), at pH=4. Whereas maximum crystallite size 64.5 nm corresponds lattice constant of 8.298 Å at pH=10. The highest magnetization (48 emu/g) value was achieved for the sample prepared at pH=7, which at the same time has a lower coercivity. The samples synthesized at pH ≥4 show superparamagnetic behavior owing to its low particle size and to zero field cooling and field cooling measurements. The ferromagnetic resonance (FMR) cavity tests analysis show that the broadened linewidth (770 Oe) and high imaginary permeability or high microwave absorption which is linked to high magnetization and low coercivity of superparamagnetic particles and their aggregation. There was a shift in the resonance field due to internal fields and cation distribution.

Impact of Process Parameters and Dopant Concentration on Structural, Magnetic, and Dielectric Properties of Dysprosium-doped Nickel-Zinc Ferrites Synthesized by Microwave Hydrothermal Method

“…Similar behavior has been observed in previous studies, where the spinel phase increases as pH increases and the α-Fe 2 O 3 phase decreases. For instance, Sadeq H. Lafta 34 synthesized Ni ferrites with varying pH values using the hydrothermal method and observed that the spinel phase started to form at pH 7. Huang et al 33 investigated the effect of pH on the formation of Co-Zn ferrites synthesized through the coprecipitation method.…”

Investigation of photocatalytic degradation of 4-nitrophenol in the presence of ferrites of MFe2O4 composition (M = Ni, Mn, Zn)

“…Саме синтез композиційних феритів призводить до поліпшення їх функціональних властивостей. Розподіл катіонів Ni 2+ , Mn 2+ та Zn 2+ по тетраедричних та октаедричних позиціях має суттєвий вплив на функціональні властивості [11].…”

Antioxidant activity and cytotoxicity of greigite nanoparticles synthesized by hydrothermal technique

“…24 It acquired its significance due to its homogeneous deposition, cost-effectiveness, environment-friendliness, ease of expansion, good crystallization, pure end product, precise control of the size, and morphology control depending on the crystal growth condition. [25][26][27] In hydrothermal processes, reaction conditions, such as solvent, temperature, 28 time, 29,30 pH value, 31 precursor concentrations, and the composition of the precursors, 32,33 have important effects on products. The hydrothermal technique is an excellent alternative to the traditional crystal growth techniques, which are capable of growing a wide range of crystals at temperatures well below their melting points and, therefore, crystals with low thermal stress.…”