Formation, Structure and Magnetic Properties of MFe2O4@SiO2 (M = Co, Mn, Zn, Ni, Cu) Nanocomposites

Abstract

The formation, structure, and thermal and magnetic properties of MFe2O4@SiO2 (M = Co, Mn, Zn, Ni, Cu) (60% MFe2O4/40% SiO2) nanocomposites produced by a modified sol-gel method, followed by annealing at 300, 600, 900 and 1200 °C, were studied. The thermal analysis and Fourier transform infrared spectroscopy showed the formation of metal-glyoxylates below 210 °C and their decomposition into the corresponding ferrite around 300 °C. The evolution of crystalline phases and variation of crystallite sizes differs from ferrite to ferrite and depends on the annealing temperature. The magnetic measurements revealed the dependence of saturation and remanent magnetization, coercivity, and anisotropy on ferrite type, annealing temperature, and particle size. By annealing the nanocomposites (NCs) at 1200 °C paramagnetic MnFe2O4, CoFe2O4, NiFe2O4 and CuFe2O4 and antiferromagnetic ZnFe2O4 are obtained.

Recent Advances in Synthesis and Applications of MFe2O4 (M = Co, Cu, Mn, Ni, Zn) Nanoparticles

“…The M S value of 7.06 emu/g for ZnFe 2 O 4 (diameter of ~17.9 nm) is lower than values of 54.6 emu/g for hydrothermal-synthesized ZnFe 2 O 4 ultrafine particles (crystallite size of ~300 nm) [101]. However, the paramagnetic behavior of ZnFe 2 O 4 was remarked upon in bulk [46] and NPs, due to the increase of an atypical Fe 3+ cation distribution in the tetrahedral coordination sites upon nanosizing [47,101].…”

“…Our previous works reported the thermal, structural, morphological, and magnetic characterization of ferrites (MFe 2 O 4 , M = Co, Mn, Zn, Ni and Cu) and doped ferrites with different divalent transition metals, produced by sol-gel synthesis [41][42][43][44][45][46]. Furthermore, since the physical, chemical, magnetic, electrical, and optical properties can be tailored by the dopant type and content, we also reviewed the potential applications of CoFe 2 O 4 and divalent transition metal-doped cobalt ferrites (M x Co 1−x Fe 2 O 4 , M = Zn, Cu, Mn, Ni, and Cd) [47].…”

Observation of intrinsic fluorescence in cobalt ferrite magnetic nanoparticles by Mn2+substitution and tuning the spin dynamics by cation distribution

“…The M s of all the NF samples varied in the range of 55.40 to 80.30 emu g À1 and did not follow any systematic trend given that the magnetic characteristics of the NFs strongly depend on several factors such as their synthetic route, crystallinity, defect state concentration, particle size, and porosity. 92,93 The bulk M s of MnFe 2 O 4 and CoFe 2 O 4 is 110 emu g À1 and 90 emu g À1 , respectively; however, in the nano-regime, it is significantly lower due to the increase in defect state and surface spins, and non-stoichiometric cation distribution. 46,64 The value of M s obtained for Co 0.4 Mn 0.6 Fe 2 O 4 is one of the highest reported to date for mixed ferrites of the same particle size.…”

An efficient and eco-compatible multicomponent synthesis of 2,4,5-trisubstituted imidazole derivatives using modified-silica-coated cobalt ferrite nanoparticles with tungstic acid

“…[33][34][35][36] Afterwards, silicacoated cobalt ferrite nanoparticles were prepared to boost the nanoparticle constancy in aqueous solutions by providing colloidal stability and inter-particle separation to prevent particles from irreversible growth and agglomeration and minimize degradation through the Stöber process by controlling the particle size, distribution and morphology by adjusting reaction parameters, such as precursor concentration, reaction time, temperature and stirring conditions. [37][38][39][40][41][42] In addition, applying exterior shell priming with hydrophobic silanes, such as tetraethyl orthosilicate (TEOS), provides an appropriate surface for further modifications. 43,44 The coupling agent, CPTMS ((3chloropropyl)trimethoxysilane), was used to provide a functionalization site by modifying the silica hydroxyl groups of the synthesized CoFe 2 O 4 @SiO 2 .…”