Influence of size distribution and field amplitude on specific loss power.

Herein we present the results of specific loss power (SLP) analysis of polydisperse water based ferrofluids, Fe₃O₄/PEG200 and Fe₃O₄/PEG6000, with average Fe₃O₄ particle size of 9 nm and 11 nm, respectively. Specific loss power was measured in alternating magnetic field of various amplitudes and at fixed frequency of 580.5 kHz. Maximum SLP values acquired were 195 W/g for Fe₃O₄/PEG200 and 60 W/g for Fe₃O₄/PEG6000 samples. The samples were labeled as superparamagnetic by magnetization measurements, but SLP field dependence showed deviation from the behavior predicted by the commonly employed linear response theory. The scope of this theory for both samples with wide particle size distribution is discussed. Deviation from the expected behavior is explained by referring to polydisperse nature of the samples and field dependent relaxation rates. [ABSTRACT FROM AUTHOR]