The effect of the ferrofluid magnetic particle concentration on the thermal diffusivity

Thermal diffusivity results obtained with the collinear mirage technique, a re reported for different concentrations surfacted ferrofluid and for a set of acid ferrofluids with variable pH values. The collinear mirage techniqu e was used because the materials are semitransparent and have low thermal d iffusivities. The results show that, as the ferrofluid magnetic particles c oncentration increases, the thermal diffusivity also increases. Their behav iour differs from that reported for ferronematics Ill. The different geomet ry of thermal waves propagating through the material can account for the di fference.