Synthesis and Surface Derivatization of Processible Co Nanoparticles

doi:10.5012/bkcs.2003.24.1.032

Cited by 13 publications

(2 citation statements)

References 31 publications

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“…The CoO-Pt core-shell nanoparticles were synthesized using the reverse micelle concept, [37][38][39] based on dissolution of a cationic surfactant in an organic solvent and the formation of spherical reverse micelle aggregates. All chemicals were purchased from Aldrich and Sigma and used without further purification.…”

Section: A Sample Preparationmentioning

confidence: 99%

Structural and magnetic properties of CoO-Pt core-shell nanoparticles

et al. 2014

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Using microemulsion methods, CoO-Pt core-shell nanoparticles (NPs), with diameters of nominally 4 nm, were synthesized and characterized by high-resolution transmission electron microscopy (HRTEM) and a suite of x-ray spectroscopies, including diffraction (XRD), absorption (XAS), absorption near-edge structure (XANES), and extended absorption fine structure (EXAFS), which confirmed the existence of CoO cores and pure Pt surface layers. Using a commercial magnetometer, the ac and dc magnetic properties were investigated over a range of temperature (2 K ≤ T ≤ 300 K), magnetic field (≤ 50 kOe), and frequency (≤ 1 kHz). The data indicate the presence of two different magnetic regimes whose onsets are identified by two maxima in the magnetic signals, with a narrow maximum centered at 6 K and a large one centered at 37 K. The magnetic responses in these two regimes exhibit different frequency dependences, where the maximum at high temperature follows a Vogel-Fulcher law, indicating a superparamagnetic (SPM) blocking of interacting nanoparticle moments and the maximum at low temperature possesses a power law response characteristic of a collective freezing of the nanoparticle moments in a superspin glass (SSG) state. This co-existence of blocking and freezing behaviors is consistent with the nanoparticles possessing an antiferromagnetically ordered core, with an uncompensated magnetic moment, and a magnetically disordered interlayer between CoO core and Pt shell.

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Section: A Sample Preparationmentioning

confidence: 99%

Structural and magnetic properties of CoO-Pt core-shell nanoparticles

et al. 2014

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“…For several decades AC susceptometers have been routinely used in research because they analyze the complex susceptibility, revealing both the magnetic response of a material and magnetic losses caused by hysteretic behaviour. Their use has expanded to characterize a wide range of materials such as magnetic materials, superconductors and, lately, magnetic nanoparticles, bio-and nano-structured materials [1][2][3][4][5]. In addition to this, they are used to characterize magnetic and phase transitions in ferromagnets, antiferromagnets, and superconductors [6,7].…”

Section: Introductionmentioning

confidence: 99%

Design and construction of a desktop AC susceptometer using an Arduino and a Bluetooth for serial interface

2018

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We designed and developed a desktop ac susceptometer for the characterization of materials. The system consists of a lock-in amplifier, an ac function generator, a couple of coils, a sample holder, a computer system with a designed software in freeware C++ code, and an Arduino card coupled to a bluetooth module. The Arduino/bluetooth serial interface allows the user to have a connection to almost any computer and thus avoids the problem of connectivity between the computer and the peripherals such as the lock-in amplifier and the function generator. The bluetooth transmitter/receiver used is a commercial device which is robust and fast. These new features reduce the size and increment the versatility of the susceptometer for it can be used with a simple laptop. To test our instrument we performed measurements on magnetic materials and show that the system is reliable at both room temperature and cryogenic temperatures (77 K). The instrument is suitable for any physics or engineering laboratory either for research or academic purposes.

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Ferromagnetic Cobalt Nanoparticles and Their Immobilization on Monomolecular Films and Chemical Templates

Zhao

Spasova

et al. 2011

Adv Funct Materials

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Monodisperse Co nanoparticles (NPs), stabilized by organic coating have been synthesized, and their immobilization on a variety of self-assembled monolayers (SAMs) bearing different terminal groups and on SAM-based chemical templates has been studied. The NPs had an average diameter of ∼ 10 nm and consisted of hcp cobalt covered by a thin ( ∼ 1 nm) oxide fi lm.They exhibited pronounced ferromagnetic properties with a blocking temperature above 380 K, which is unusual for the given NP size and is presumably related to the high magnetocrystalline anisotropy associated with the crystallographic perfection of the NPs. The NPs were found to attach selectively to the SAMs bearing the thiol tail group, whereas no stable immobilization to other SAMs, over the electrostatic forces, could be achieved. Finally, based on the results for the individual SAMs, high-contrast 2D structures of the Co NPs were fabricated on SAM-based chemical templates on both microand nanometer length scales. The templates were prepared by irradiationpromoted exchange reaction lithography, taking an OH-terminated aliphatic SAMs as the primary template and thiol-bearing aromatic molecules as the substituents.

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Synthesis and Surface Derivatization of Processible Co Nanoparticles

Cited by 13 publications

References 31 publications

Structural and magnetic properties of CoO-Pt core-shell nanoparticles

Structural and magnetic properties of CoO-Pt core-shell nanoparticles

Design and construction of a desktop AC susceptometer using an Arduino and a Bluetooth for serial interface

Ferromagnetic Cobalt Nanoparticles and Their Immobilization on Monomolecular Films and Chemical Templates

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