Carbon encapsulation of elemental nanoparticles by spark discharge


Livan P., Öztürk T.

JOURNAL OF MATERIALS SCIENCE, vol.53, pp.14350-14360, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 53
  • Publication Date: 2018
  • Doi Number: 10.1007/s10853-018-2647-z
  • Title of Journal : JOURNAL OF MATERIALS SCIENCE
  • Page Numbers: pp.14350-14360

Abstract

A study was carried out on the carbon encapsulation of a number of elements using a spark discharge generator. The study showed that elements W, V, Ti, and Si formed carbides which were encapsulated successfully by graphitic layers forming a sound core-shell structure. Copper formed a partially filled core-shell structure, attributed to its relatively low condensation temperature, where considerable shrinkage seemed to have occurred after the encapsulation. Mg could not be encapsulated in a core-shell form but rather yielded an embedded structure where Mg is condensed onto already condensed carbonaceous material. Analysis of current observations coupled with those already reported data imply a simple mechanism for encapsulation. Metals/compounds that are solid above the condensation temperature of carbon give rise to a sound core-shell structure. Elements whose condensation temperature is less than that of carbon could still produce core-shell particles but they may be partially filled. It is estimated that the process of graphitic encapsulation may be complete around 1900 K and partially filled core-shell structure might develop depending on the volume shrinkage upon cooling to room temperature. Elements/compounds whose condensation temperature is below the encapsulation temperature fail to develop core-shell structure. Instead, they form embedded composite structure.