Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

Abstract

Three kinds of spinel ferrite nanocrystals, MFe2O4 (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH4) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (Ms). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.

Ethanol-assisted synthesis and adsorption property of flake-like NiFe2O4 nanoparticles

“…Actually, the ethanol addition increases the volume anisotropy and interparticle interaction of nanoparticles, which leads to a higher blocking temperature T B of the as-synthesized NiFe 2 O 4 ferrites [22]. Additionally, it is worthy to note that, due to the occurrence of some extremely small particles, the ZFC curves of all the samples show a sharp peak at 7.2-12K, which is in perfect accordance with the results in the previous reports [23,24]. In addition, for FC curves of all the four samples, an approximate temperature-independent part at above 20 K can be observed.…”

The glaze production technology of an early Ottoman pottery (mid-14th(?)-16th century): The case of ‘Miletus Ware’

“…7, spectrum 1) and nickel-iron (Fig. 7, spectrum 2) based-spinels based respectively on a CoFe 2 O 4 and NiFe 2 O 4 like structure (Wang et al, 2015), which correlates well with the glaze's chemical compositions. Similar inclusions were observed in 9th century Samarra faience blue glazes (Kleinmann, 1991), and in 15th-16th century Hispano-Moresque tiles (Coentro et al, 2014(Coentro et al, , 2018.…”

Chemical Structure of Fe–Ni Nanoparticles for Efficient Oxygen Evolution Reaction Electrocatalysis

“…The nickel ferrite (NiFe 2 O 4 ) reference is known to have an inverse spinel fcc crystal structure, where the divalent nickel occupies only octahedral sites, while trivalent iron equally occupies both octahedral and tetrahedral interstitial sites within the crystal structure. 58 In addition to the oxidation state, the pre-edge feature can also provide information about the metal coordination geometry 59 of a material. Comparison to these reference spectra pre-edge peak shape and positions suggests that iron atoms that are in the +3 oxidation state may be chemically situated in an octahedral coordination environment, while a population of the iron atoms may be in a zero valent metallic state.…”