Characterisation and magnetic behaviour of nickel nanoparticles encapsulated in carbon

Patricia B. Oliete, T. Cristina Rojas, Asunción Fernández, Aharon Gedanken, Yuri Koltypin, Fernando Palacio

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

In the previous papers, we reported the synthesis of nickel nanocrystals encapsulated in an amorphous carbon matrix by a method that consists in the sonochemical decomposition of the Ni(COD)2 organometalic precursor followed by a heating treatment in vacuum. Both as-prepared and heated samples have been further characterised in the present paper by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) to determine the microstructure and the stability of the nickel nanocrystals for long periods of air storage. It has been shown that carbon is protecting the nickel nanocrystals from oxidation leading to a magnetic behaviour of the sample congruent with the superparamagnetic properties of single domain particles. The analysis of the frequency-dependent ac susceptibility leads to two well-defined distributions of particle size consistent with those observed in TEM experiments. The effective anisotropy constant has been determined for the two particle sizes of nickel nanoparticles.

Original languageEnglish
Pages (from-to)2165-2171
Number of pages7
JournalActa Materialia
Volume52
Issue number8
DOIs
StatePublished - 3 May 2004

Bibliographical note

Funding Information:
The authors thank the DGES (Project PB96-0863-C02-02) and the Comision Interministerial de Ciencia y Tecnologia (CICYT-MAT2000-1388-C03-03) for financial support.

Keywords

  • Encapsulated nickel particles
  • Magnetic properties
  • Nanocomposite
  • Nanocrystalline microstructure

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