Surface functionalization is found to prevent the reduction of saturation magnetization in magnetite nanoparticles, but the underlying mechanism is still to be clarified. Through a wide set of hybrid density functional theory (HSE06) calculations on Fe3O4 nanocubes, we explore the effects of the adsorption of various ligands (containing hydroxyl, carboxylic, phosphonic, catechol, and silanetriol groups), commonly used to anchor surfactants during synthesis or other species during chemical reactions, onto the spin and structural disorder, which contributes to the lowering of the nanoparticle magnetization. The spin-canting is simulated through a spin-flip process at octahedral Fe ions and correlated with the energy separation between O2- 2p and FeOct3+ 3d states. Only multidentate bridging ligands hamper the spin-canting process by establishing additional electronic channels between octahedral Fe ions for an enhanced ferromagnetic superexchange interaction. The presence of anchoring organic acids also interferes with structural disorder, by disfavoring surface reconstruction.

Bianchetti, E., Di Valentin, C. (2022). Effect of Surface Functionalization on the Magnetization of Fe3O4 Nanoparticles by Hybrid Density Functional Theory Calculations. THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 13(40), 9348-9354 [10.1021/acs.jpclett.2c02186].

Effect of Surface Functionalization on the Magnetization of Fe3O4 Nanoparticles by Hybrid Density Functional Theory Calculations

Bianchetti, Enrico
Primo
;
Di Valentin, Cristiana
Ultimo
2022

Abstract

Surface functionalization is found to prevent the reduction of saturation magnetization in magnetite nanoparticles, but the underlying mechanism is still to be clarified. Through a wide set of hybrid density functional theory (HSE06) calculations on Fe3O4 nanocubes, we explore the effects of the adsorption of various ligands (containing hydroxyl, carboxylic, phosphonic, catechol, and silanetriol groups), commonly used to anchor surfactants during synthesis or other species during chemical reactions, onto the spin and structural disorder, which contributes to the lowering of the nanoparticle magnetization. The spin-canting is simulated through a spin-flip process at octahedral Fe ions and correlated with the energy separation between O2- 2p and FeOct3+ 3d states. Only multidentate bridging ligands hamper the spin-canting process by establishing additional electronic channels between octahedral Fe ions for an enhanced ferromagnetic superexchange interaction. The presence of anchoring organic acids also interferes with structural disorder, by disfavoring surface reconstruction.
Articolo in rivista - Articolo scientifico
Magnetite, Reconstruction, Hybrid DFT, Spin Disorder, Saturation magnetization, Anchoring ligands
English
9348
9354
7
Bianchetti, E., Di Valentin, C. (2022). Effect of Surface Functionalization on the Magnetization of Fe3O4 Nanoparticles by Hybrid Density Functional Theory Calculations. THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 13(40), 9348-9354 [10.1021/acs.jpclett.2c02186].
Bianchetti, E; Di Valentin, C
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/396142
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