Synthesis and Magnetic Properties of FePt@MnO Nano-heteroparticles

Abstract

Monodisperse FePt@MnO nano-heteroparticles with different sizes and morphologies were prepared by a seed-mediated nucleation and growth technique. Both size and morphology of the individual domains could be controlled by adjustment of the synthetic parameters. As a consequence, different particle constructs, including dimers, dumbbell-like particles, and flowerlike particles, could be obtained by changing the polarity of the solvent. The FePt@MnO nano-heteroparticles were thoroughly characterized by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses and superconducting quantum interference device (SQUID) magnetometry. Due to a sufficient lattice match, the MnO nanoparticles (NPs) preferentially grow on the (111) surfaces of the fcc-FePt seeds. Furthermore, the surface spins of the antiferromagnetic MnO domains pin the magnetic moments of the ferromagnetic FePt NPs, which leads to an exchanged biased magnetic hysteresis.

Colloidal Magnetic Heterostructured Nanocrystals with Asymmetric Topologies: Seeded-Growth Synthetic Routes and Formation Mechanisms

“…Examples of MHNCs derived from heterogeneous deposition pathways are collected in Figures 2B-Q. Thermal decomposition of metallorganic precursors in the presence of preformed noble metal, Fe 3 O 4 , FePt, or UO 2 seeds in non-coordinating solvents, such as octadecene (ODE) or phenyl ether containing oleic acid (OLAC), oleyl amine (OLAM), and/or tri-n-octyl phosphine (TOP) surfactants at 200-300°C has enabled access to hetero-dimer HNCs made of two nearly spherical and/or cubic-shaped domains epitaxially interconnected, such as of Me-Fe 3 O 4 (Me = Au, AuAg, PtPd, AuPd, AuPt, Pt, Pd, Ni, Cu) (Yu et al, 2005;Shi et al, 2006b;Choi et al, 2008;Wei et al, 2008;Wang et al, 2009aGeorge et al, 2011aGeorge et al, , 2013Jang et al, 2011a;Lin and Doong, 2011;Nakhjavan et al, 2011;Zhai et al, 2011;Leung et al, 2012;Sun et al, 2012;Kim and Song, 2014;Victor et al, 2015), Fe 3 O 4 -MnO , Au-MnO (Choi et al, 2008;Schladt et al, 2010) (He et al, 2009;Lee et al, 2010a;Wu et al, 2011a;Schladt et al, 2012;Liu et al, 2014;Yang et al, 2015), respectively. Depending on the geometric features of the two-component domains, these heterostructures exhibit various morphological profiles, spanning from peanut-, dumbbell-, brick-to flower-like (Figures 2B-D).…”

EFFECT OF SYNTHESIS PARAMETERS ON DIMENSIONAL CHARACTERISTICS OF Fe3O4 NANOPARTICLES: NEURAL-NETWORK RESEARCH

“…В последние десятилетия особое внимание исследователейпрактиков привлекают наноразмерные магнитные материалы [1][2][3][4][5], которые нашли широкое применение в различных областях науки и техники: в терапии и диагностике заболеваний, для обеспечения адресной и направленной доставки лекарств, в качестве катализаторов и сорбентов, как чувствительные элементы датчиков магнитных полей, в системах записи и хранения информации для увеличения емкости и скорости считывания и записи. В связи с чем большое количество работ направлено на разработку новых методов получения и исследование свойств магнитных наноматериалов [6,7].…”

Magnetism of monomer MnO and heterodimer FePt@MnO nanoparticles

“…In addition, heterodimer NPs composed of an AF MnO NP in close contact with a FM FePt NP are a novel type of a multifunctional nanomagnet 30 . At the interface between the FePt NPs and the MnO NPs, an exchange bias effect 31,32 occurs.…”

“…At the interface between the FePt NPs and the MnO NPs, an exchange bias effect 31,32 occurs. The FM spins in FePt NPs are magnetically stabilized by the MnO NPs subunits and thus the blocking temperature of the FePt NPs is increased 30 .…”