A facile route to synthesis of CoPt magnetic nanoparticles

Liu, Yang; Yang, Yanting; Zhang, Yongjun; Wang, Yaxin; Zhang, Xiaolong; Jiang, Yuhong; Wei, Maobin; Liu, Yanqing; Liu, Xiaoyan; Yang, Jing

doi:10.1016/j.materresbull.2012.11.019

Cited by 24 publications

(5 citation statements)

References 22 publications

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“…To explore lattice constant (a), lattice angle (α), unit cell volume (V), and Bragg positions of the samples (see Figure 1), we were carried out Rietveld refinements of XRD data using Full Prof software. We investigated the crystalline symmetry as the Fm3 " (JCPDS: 15-0806) space groups of fcc-Co cubic phases for both samples from the simulation [24]. The lattice constants were found to be 3.86 Å and 3.88 Å for the samples prepared under Ar pressure and air, respectively [25].…”

Section: Resultsmentioning

confidence: 99%

Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

Kaya

Adanur

Akyol

et al. 2020

Adıyaman University Journal of Science

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We have studied the effect of preparation methods, under argon gas and in the air environment, on the cobalt oxide formation of CoPt nanoparticles by the polyol process. The formation of cobalt oxide for both samples was investigated by the x-ray diffraction (XRD) method and cobalt oxide peaks are observed in the air prepared sample. Rietveld refinement analyses revealed that all samples exhibit a chemically distorted cubic crystal structure. The average particle size was determined <8 nm by scanning electron microscopy (SEM) and energydispersive x-ray spectroscopy (EDS) was revealed the chemical compositions with possible oxygen formation in the structure. The blocking temperature is reduced to 28 K in the air prepared sample due to cobalt oxide formation. The hysteresis gap disappeared above the blocking temperature and no saturation is observed up to ±5 T external field due to the system switching

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Section: Resultsmentioning

confidence: 99%

Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

Kaya

Adanur

Akyol

et al. 2020

Adıyaman University Journal of Science

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“…[1] However, the random size of nanoparticles is a main disadvantage in view of the practical applications of this material. [29] One of our objectives of this research is to solve this problem by using GLAD with polystyrene spheres. From the SEM observation, we can clearly see that all the nanowires grow on the polystyrene spheres.…”

Section: Resultsmentioning

confidence: 99%

Characterization of CoPt nanowire fabricated by glancing angle deposition

et al. 2015

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CoPt and Co nanowire films were deposited by the Glancing Angle Deposition (GLAD) method. All samples are deposited on Si substrates that were covered by polystyrene spheres to assist the alignment of nanowires. SEM observation results show that the length and diameter of nanowires are uniform for all samples. According to the result of XRD, the crystal structure of CoPt is fcc. The angular dependence of magnetization of the nanowires shows that the easy axis of magnetization is along the growth direction of the nanowires.

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“…Although much higher coercivities would be required for use in BPM, the coercivity values obtained for CoPt nanoparticles by synthesized mediated and designed peptides provided a significant increase from a room temperature coreduction synthesis compared to literature values. CoPt NPs produced using the reverse micelle method typically have coercivities of 0–25 Oe prior to annealing; , synthesis using the sol–gel method typically results in NPs that only have high coercivity values after annealing, and NPs synthesized using a high temperature reduction method have coercivities of 0–36 Oe. ,− Typically, higher coercivities than this are only observed after annealing has been carried out at temperatures greater than 600 °C for at least 1 h. Therefore, being able to achieve coercivities up to 132 Oe using a room temperature coreduction synthesis method that does not require any harsh solvents or high temperatures is a very positive step forward in the synthesis of L1 0 CoPt NPs. This is also a massive improvement on the coercivities achieved with the LS in our precipitation.…”

Section: Nanoparticle Synthesis Using Selected and Designed Peptidesmentioning

confidence: 99%

Systematic Screening and Deep Analysis of CoPt Binding Peptides Leads to Enhanced CoPt Nanoparticles Using Designed Peptides

et al. 2020

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Using protein and peptide additives to direct the crystallization of inorganic materials is a very attractive and environmentally friendly strategy to access complex and sometimes inaccessible mineral phases. CoPt is a very desirable highmagnetoanisotropic material in its L1 0 phase, but this is acquired by annealing at high temperatures which is incompatible with delicate nanomaterial assembly. Previous studies identified one peptide with high affinity to CoPt and four peptides with high affinity to FePt L1 0 phase nanoparticles (NPs) through phage display biopanning selection. While synthesis mediated by these peptides offered a small degree of L1 0 character to the NPs, they do not have the magnetoanistropy required for applications. In this study, we improve the activity of peptide directed crystallization by designing second generation peptides. We use the five literature sequences (LS) to probe the binding affinity deeper through dissection (alanine scanning), reduction (truncations), and substitution of the LS to find key amino acids and motifs. This is performed using a SPOT peptide array, importantly probing interactions at three stages of NP formation: with precursor, during synthesis, and with NPs. We found four universal features: 1) the importance of basic residues, particularly lysine flanking both ends of the sequence; 2) the importance of methionine; 3) shorter sequences show higher affinity than longer ones; and 4) acidic residues have a negative impact on binding with aspartic acid less favorable than glutamic acid. However, an acidic amino acid benefits, presumably to balance charge. The short motif KSLS had high affinity in all assays. Three sequences were selected from the screening, and three sequences were designed from the rules above. These were used to mediate a green synthesis of CoPt nanoparticles. The screened peptides mediated the formation of NPs with improved coercivity (90−110 Oe) compared to the LS (30−80 Oe), while the designed peptides facilitated formation of CoPt NPs with the highest coercivity (109 to 132 Oe), representing a massive improvement on L1 0 character. This result along with deeper insight this methodology brings offers vast potential for the future.

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A facile route to synthesis of CoPt magnetic nanoparticles

Cited by 24 publications

References 22 publications

Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

Characterization of CoPt nanowire fabricated by glancing angle deposition

Systematic Screening and Deep Analysis of CoPt Binding Peptides Leads to Enhanced CoPt Nanoparticles Using Designed Peptides

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