Synthesis of crystallographically oriented olivine aggregates using colloidal processing in a strong magnetic field

Sanae Koizumi, Tohru Suzuki, Yoshio Sakka, Kosuke Yabe, Takehiko Hiraga

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This study develops a fabrication technique to obtain Fe-free and Fe-bearing (Fe:Mg = 1:9) olivine aggregates not only with high density and fine grain size but with crystallographic preferred orientation (CPO). A magnetic field (≤12 T) is applied to synthetic, fine-grained (~120 nm), olivine particles dispersed in solvent. The alignment of certain crystallographic axes of the particles with respect to a magnetic direction is anticipated due to magnetic anisotropy of olivine. The dispersed particles are gradually consolidated on a porous alumina mold covered with a solid–liquid separation filter during drainage of the solvent. The resultant aligned consolidated aggregate is then isostatically pressed and vacuum sintered. We find that (1) preparation of fully reacted olivine particles, with less propensity to coalesce; (2) preparation of a suspension with highly dispersed particles; and (3) application of a certain strength of the magnetic field are essential to obtain well-sintered and well-aligned aggregates. High density (i.e., <1 vol% porosity) and fine grain size (~1 μm) Fe-free and Fe-bearing olivine aggregates were successfully synthesized with uniaxially aligned a- and c-axes, respectively. Attempts to uniaxially align the magnetization hard axis and to triaxially align Fe-bearing olivine by rotating the suspension in the magnetic field succeeded in obtaining weakly developed CPO aggregates.

Original languageEnglish
Pages (from-to)689-706
Number of pages18
JournalPhysics and Chemistry of Minerals
Volume43
Issue number10
DOIs
Publication statusPublished - 2016 Nov 1
Externally publishedYes

Keywords

  • Crystallographic preferred orientation
  • Magnetic alignment
  • Olivine
  • Sintering

ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology

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