Gradient of zinc content in core–shell zinc ferrite nanoparticles – precise study on composition and magnetic properties

Abstract

Structure, magnetic properties and chemical composition of synthesized zinc ferrite nanoparticles were characterized by a broad spectrum of methods.

Effect of Thermal Treatment at Inert Atmosphere on Structural and Magnetic Properties of Non-stoichiometric Zinc Ferrite Nanoparticles

“…For samples S1-S3, the amount of zinc in the structure is larger than that obtained via ICP-OES. Thus, such a large amount of Zn may suggest a higher accumulation of zinc in the surface layer of the nanoparticles, [6] because the XPS information depth is about 4.5 nm for Fe 3 O 4 and 10 nm for the organic layers. [71,72] In addition, the chemical composition of the surface of particles was examined before and after thermal treatment.…”

“…These reveal enhanced physical properties, e.g., magnetization and permeability, compared to their bulk counterparts. [1][2][3][4][5][6][7][8] Selected systems, for example, zinc ferrite, have low toxicity, which is advantageous in terms of applications in biotechnology/biomedicine (drug delivery, magnetic hyperthermia, imaging), [9][10][11][12] as magnetic fluids [13][14][15] and in environmental remediation. [16][17][18][19] In addition, zinc ferrites are also promising candidates for application in magnetic storage [20] or as a photo-absorber material for light-driven water splitting.…”

Shell-mediated control of surface chemistry of highly stoichiometric magnetite nanoparticles

“…Then, the system was heated directly to 300 °C (heating rate 20 °C min -1 ) and kept at that temperature for 60 min, while maintaining continuous N 2 bubbling and magnetic stirring. A 1:2 Zn(acac) 2 :Fe(acac) 3 molar ratio was employed to obtain a Zn 0.6 Fe 2.4 O 4 composition in the shell since the effective Zn:Fe molar ratio in the shell is expected to be lower than the precursors ratio due to differences in the reaction mechanism of metal acetylacetonates 52,53 . The obtained NPs were washed twice with a hexane:ethanol 1:8 mixture and are easily dispersed in hexane or other non-polar solvents.…”

Thermal Decomposition Pathways of ZnxFe3–xO4 Nanoparticles in Different Atmospheres

“…Comprehensive approach to design and synthesis of nanomaterials significantly widened possibilities of their application throughout vast life areas. − Nanoparticles with magnetic properties have been very interesting materials for basic research and technological applications for years. − The special attention of scientists is on ferrite nanoparticles with a spinel structure: (M 1– x Fe x )­[M x Fe 2– x ]­O 4 , where the parentheses and square brackets denote the (tetrahedral) and [octahedral] sites (later Td and Oh, respectively), and M is a transition metal (for example, Zn, Mg, Co, or Fe). ZnFe 2 O 4 nanoparticles (ZFN) are the subject of investigation, because of their unique magnetic properties, memory effect, superspin-glass ordering, low toxicity, specific microwave absorption, electrical properties, and photocatalytic activity. ,− ,,,, …”

“…Ferrites of a spinel structure provide a possibility of controlling chemical and physical properties. ,,, On the nanoscale, at room temperature (RT), ZFN reveal superparamagnetic response, while at a cryogenic temperature of −268 °C (∼5 K), they show ferrimagnetic properties. ,,− Alterations are possibly caused by, e.g., the nanoparticle size, applied magnetic field, or dipole–dipole interactions. , …”