Deposition of magnetic colloidal particles on graphite and mica surfaces driven by solvent evaporation

K J Mutch, V Koutsos, P J Camp

Research output: Contribution to journalArticlepeer-review

Abstract

The deposition of colloidal magnetite particles onto graphite and mica surfaces induced by solvent evaporation is studied using atomic force microscopy. After evaporation under ambient conditions we observe polydisperse beadlike aggregates; the mean aggregate diameter is larger on graphite than on mica. After evaporation at elevated temperatures we observe a variety of effects, including enhanced particle aggregation and spinodal-like deposition patterns. To explain these trends, we propose mechanisms involving the wetting properties of the solvent. We have also made a brief study of the effects of applied magnetic fields on the formation of aggregates. A field applied parallel to the surface enhances aggregation and favors deposition patterns characteristic of hole-nucleation processes. A perpendicular field leads to a reduction in aggregate size and favors a homogeneous distribution of particles on the surface. These effects are explained in terms of the likely orientation of the dipolar particles on the surface.

Original languageEnglish
Pages (from-to)5611-5616
Number of pages6
JournalLangmuir
Volume22
Issue number13
DOIs
Publication statusPublished - 20 Jun 2006

Keywords

  • DIPOLAR HARD-SPHERES
  • CRYOGENIC ELECTRON-MICROSCOPY
  • ATOMIC-FORCE MICROSCOPY
  • SMALL-ANGLE NEUTRON
  • LONG-RANGE FORCES
  • THIN LIQUID-FILMS
  • ORIENTATIONAL STRUCTURE
  • PATTERN-FORMATION
  • IRON FERROFLUIDS
  • ZERO-FIELD

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