Synthesis of L10 ferromagnetic CoPt nanopowders using a single-source molecular precursor and water-soluble support

Abstract

Reductive decomposition of CoPt(CO) 4 (dppe)Me/NaCl composite powder (2 : 98 CoPt precursor : NaCl mass ratio) at 650 C under getter gas (9 : 1 N 2 /H 2) gives black CoPt/NaCl nanocomposites with minimal CoPt nanoparticle coalescence. Aqueous dissolution of the NaCl support permits isolation of ferromagnetic L1 0 CoPt nanoparticles of ca. 11 nm average diameter as free-flowing black powders. Asprepared CoPt nanopowders exhibit moderate coercivity (4.0 kOe) at 300 K and high coercivity (26.0 kOe) at 5 K consistent with formation of polydisperse L1 0 CoPt nanoparticles having high purity and high crystallinity. Co 1 Pt 1 nanoparticles are formed with good control of alloy stoichiometry using a single-source precursor by a convenient, scalable single-step process.

Ferromagnetic L10-Structured CoPt Nanoparticles for Permanent Magnets and Low Pt-Based Catalysts

“…Previous studies have presented numerous methodologies on the chemical synthesis of CoPt nanoparticles. ,− Typically, the nanoparticles produced via liquid chemical approaches possess the disordered face-centered cubic (fcc) crystal structure and are superparamagnetic or weakly ferromagnetic at room temperature. To produce the L1 0 crystal structure with more interesting chemical and magnetic properties, thermal treatment (annealing) at temperatures of 700 °C and above under an inert atmosphere is required. − In general, nanoparticle annealing usually results in particle growth and sintering/agglomeration, making them not suitable for practical magnetic or catalytic applications. The addition of noble metals in CoPt, in contrast to the FePt, does not affect the ordering temperature significantly; however, Sb doping reduces the ordering temperature, but still, an annealing at 400 °C is required to reach a 1 kOe coercivity at room temperature .…”

Magnetic Force-Induced Alignment of Microtubules by Encapsulation of CoPt Nanoparticles Using a Tau-Derived Peptide

“…Thus, it can be assumed that the linear-chain assembly of CoPt NPs inside MTs in the “After” method is essential for obtaining a significant response to magnetic fields in contrast to the isolated CoPt NPs in MTs in the “Before” method. The linear-chain assembly of CoPt NPs inside MTs possibly serves like ferromagnetic nanowires and the direction of the magnetic dipole moment interaction between the adjacent CoPt NPs is possibly uniform as reported previously. , However, it is also possible that the CoPt NPs smaller than 10 nm are superparamagnetic. , When the MTs and CoPt NPs were prepared without CBP–TP in the “After” method, the resulting MTs showed no response to the magnetic field (Figure c and Figure S12). This result indicates that the encapsulation of CoPt NPs by using CBP–TP was required for obtaining an efficient magnetic response.…”

“…10,14 However, it is also possible that the CoPt NPs smaller than 10 nm are superparamagnetic. 50,51 When the MTs and CoPt NPs were prepared without CBP−TP in the "After" method, the resulting MTs showed no response to the magnetic field (Figure 3c and Figure S12). This result indicates that the encapsulation of CoPt NPs by using CBP−TP was required for obtaining an efficient magnetic response.…”

Metallopolymer precursors to L10-CoPt nanoparticles: synthesis, characterization, nanopatterning and potential application

“…( 001) and ( 110) peaks (which are the characteristic peaks for L1 0 phase CoPt alloy NPs) are clearly observed at ∼24°and ∼33°, respectively. 21,22 The apparent splitting of the (200)/(002) peak signifies a tetragonality of the NPs. Besides, no Co x N y and Pt x N y phases are observed in the PXRD pattern.…”

“…21 Lukehart et al also reported the direct synthesis of L1 0 CoPt NPs by using a single-source molecular precursor. 22 However, as far as the magnetic data recording application is concerned, it is still very desirable to develop a suitable precursor with excellent film-forming properties and solution processability which can be used for the direct nanopatterning of L1 0 CoPt NPs.…”