Silica coating of Co-Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone)

Yoshio Kobayashi, Hidekazu Kakinuma, Daisuke Nagao, Yasuo Ando, Terunobu Miyazaki, Mikio Konno

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

This article describes a method for silica coating of Co-Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone) (PVP) as a stabilizer. The Co-Pt nanoparticles were prepared in an aqueous solution at 25-80 °C from CoCl2 (3.0 × 10-4 M), H 2PtCl6 (3.0 × 10-4 M), PVP (0-10 g/L), and NaBH4 (4.8 × 10-3-2.4 × 10-2 M). The silica coating was performed for the Co-Pt nanoparticle colloid containing the PVP ([Co] = [Pt] = 3.0 × 10-5 M) at 25 °C in (1/4) (v/v) water/ethanol solution with tetraethoxyorthosilicate (TEOS) (7.2 × 10-5-7.2 × 10-3 M) and ammonia (0.1-1.0 M). Silica particles, which had an average size of 43 nm and contained multiple cores of Co-Pt nanoparticles with a size of ca. 8 nm, were produced at 1.4 × 10-3 M TEOS and 0.5 M ammonia after the preparation of Co-Pt nanoparticles at 80 °C, 5 g/L PVP, and 2.4 × 10-2 M NaBH4. Their core particles were fcc Co-Pt alloy crystallites. Their saturation magnetization was 2.0-emu/g sample, and their coercive field was 12 Oe.

Original languageEnglish
Pages (from-to)1787-1794
Number of pages8
JournalJournal of Nanoparticle Research
Volume11
Issue number7
DOIs
Publication statusPublished - 2009 Oct 1

Keywords

  • Alloy
  • Co-Pt
  • Core-shell
  • Magnetic media
  • Particle
  • Poly(vinylpyrrolidone)
  • Silica
  • Sol-gel
  • Storage

ASJC Scopus subject areas

  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Modelling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics

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