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Phasenverhalten von Mischungen von Ferrofluiden und nicht- magnetischen Kolloiden

English title Phase behavior of mixtures of ferrofluids and non- magnetic colloids
Applicant Gasser Urs
Number 113756
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Electrical Engineering
Start/End 01.08.2007 - 30.11.2011
Approved amount 156'677.00
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Keywords (5)

Soft Condensed Matter; Ferrofluides; Colloids; Magnetism; Nanoparticles

Lay Summary (English)

Lead
Lay summary
The fabrication of tailored structures on the nano- and micrometer scale is one of the hot topics in soft condensed matter research using colloids,nano- or micrometer sized particles suspended in a solvent. Good control of such suspensions can be achieved, because the interactions between colloidal particles in suspension can be tailored to some extent. Liquids, crystals, gels, and glasses are commonly observed and, in many cases, phase transitions from one state to another can be induced at will by changing an easily accessible parameter such as the salt concentration of the solvent.
Suspensions of ferro- or paramagnetic colloidal particles - ferrofluids - show interesting rheological properties that can be tuned with an external magnetic field. However, ferrofluids are also of great interest due to the structural ordering of the magnetic particles that is induced by a magnetic field. Evidence of needle-like, columnar, lamellar, and pseudo-crystalline structures have been found.
Therefore, the question arises whether ferrofluids can be used for the manipulation of non-magnetic (diamagnetic) particles to induce structural order among non-magnetic particles. The exploration of the interplay between non-magnetic and magnetic colloids and their phase behavior is the goal of this project. Generally, it is found that the onset of structural ordering among non-magnetic particles is facilitated in a mixture of magnetic and non-magnetic colloids in a magnetic field. In some cases it could be shown that this effect is not due to magnetostatic interactions but due to correlations between paramagnetic and non-magnetic particles.A mayor obstacle in the exploration of the structures and phase transitions in such mixtures is the strong absorption of visible light of ferrofluids. In many cases this makes microscopy and light scattering studies impossible; both techniques are important tools in colloidal physics. Experimental techniques that are applicable to opaque samples are needed for ferrofluids; neutron- and X-ray scattering are among the most important.
The Paul Scherrer Institute is an excellent environment for this work, since these experimental tools are available.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Magnetic properties of silica coated spindle-type hematite particles
Reufer M, Dietsch H, Gasser U, Grobety B, Hirt AM, Malik VK, Schurtenberger P (2011), Magnetic properties of silica coated spindle-type hematite particles, in JOURNAL OF PHYSICS-CONDENSED MATTER, 23(6), 065102-1-11.
Morphology and Orientational Behavior of Silica-Coated Spindle-Type Hematite Particles in a Magnetic Field Probed by Small-Angle X-ray Scattering
Reufer M, Dietsch H, Gasser U, Hirt A, Menzel A, Schurtenberger P (2010), Morphology and Orientational Behavior of Silica-Coated Spindle-Type Hematite Particles in a Magnetic Field Probed by Small-Angle X-ray Scattering, in JOURNAL OF PHYSICAL CHEMISTRY B, 114(14), 4763-4769.

Collaboration

Group / person Country
Types of collaboration
Adolphe Merkle Institut, Universität Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Associated projects

Number Title Start Funding scheme
138202 Phasenverhalten von Mischungen von magnetischen und nicht-magnetischen Kolloiden 01.12.2011 Project funding (Div. I-III)
132128 Phase behavior of concentrated microgel suspensions 01.08.2011 Project funding (Div. I-III)

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