Shaping Magnetite Nanoparticles from First-principles

Abstract

Iron oxide magnetic nanoparticles (NPs) are stimuli-responsive materials at the forefront of nanomedicine. Their realistic finite temperature simulations are a formidable challenge for first-principles methods. Here, we use density functional tight binding to open up the required time and length scales and obtain global minimum structures of Fe3O4 NPs of realistic size (1400 atoms, 2.5 nm) and of different shapes, which we then refine with hybrid density functional theory methods to accomplish proper electronic and magnetic properties, which have never been accurately described in simulations. On this basis, we develop a general empirical formula and prove its predictive power for the evaluation of the total magnetic moment of Fe3O4 NPs. By converting the total magnetic moment into the macroscopic saturation magnetization, we rationalize the experimentally observed dependence with shape. We also reveal interesting reconstruction mechanisms and unexpected patterns of charge ordering.

References in corpus (8)

• Long Range Charge Ordering in Magnetite Below the Verwey Transition
• Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface
• Charge and orbital order in Fe_3O_4
• Direct observation of t2g orbital ordering in magnetite
• Self-assembly and self-orientation of truncated nano-octahedra of magnetite
• Modelling Realistic TiO2 Nanospheres: a Benchmark Study of SCC-DFTB against Hybrid DFT
• An efficient way to model complex magnetite: assessment of SCC-DFTB against DFT
• Verwey transition in single magnetite nanoparticles

Cited by in corpus (5)

• Insight into the interface between Fe${}_3$O${}_4$(001) surface and water overlayers through multiscale molecular dynamics simulations
• Oxidation State Dynamics and Emerging Patterns in Magnetite
• Parametrization of the Fe-Owater cross-interaction for a more accurate Fe3O4/water interface model and its application to a spherical Fe3O4 nanoparticle of realistic size
• Mechanism of spin ordering in Fe${}_3$O${}_4$ nanoparticles by surface coating with organic acids
• Atomistic modeling of functionalized magnetite surfaces with oxidation states