Magnetic Soret effect in a hydrocarbon based colloid containing surfacted Mn-Zn ferrite particles

The Soret effect has been investigated in a hydrocarbon based magnetic flui d containing surfacted Mn0.5Zn0.5Fe2O4 nanoparticles with a magnetic volume concentration of 2.3%. The magnetic fluid fills up a vertical diffusion co lumn which consists of a flat vertical channel between two walls and two re servoirs at the ends of the channel. One wall of the channel is being heate d while the another one is cooled, maintaining a temperature gradient over the channel's width that leads to separation of particles due to the Soret effect as well as the convective flow in the channel. The combination of th e two mentioned effects brings up a measurable change of the concentration of magnetic particles in both reservoirs. The results have been obtained fo r uniform magnetic fields, aligned parallelly and normally to the temperatu re gradient respectively, by measuring the concentration of magnetic partic les in the reservoirs. Obtained results are in good qualitative agreement w ith thermodiffusion column theory, published earlier (E. Blums, J. Magn. Ma gn. Mater. 149 (1995) 111). (C) 1999 Elsevier Science B.V. All rights reser ved.