Properties of Mn-Zn ferrite nanoparticles for aqueous ferrofluids

E. Auzans¹ - D. Zins² - M. Maiorov¹ - E. Blums¹ - R. Massart²

¹ Institute of Physics, Latvian University, Salaspils-1, LV-2169, Latvia
² Laboratoire LI2C, Colloides Magnetiques, Case courrier 63, Universite P. et M.Curie, 75252 Paris Cedex 05, France

Abstract
Mn-Zn ferrite particles with different Zn substitution and cationic ferrofluids on their base are produced by chemical synthesis. Increasing of Zn substitution leads to smaller size of synthesised particles, as well as to higher content of associated water in them. Specific magnetisation and thermomagnetic coefficient of particles significantly decrease when Zn substitution exceeds value 0.5. Special chemical procedures are applied for obtaining stable cationic ferrofluids. After this treatment particles exhibit higher magnetisation and thermomagnetic coefficients. Particles of smaller size obtained by fractionation of polydispersed samples demonstrate higher content of associated water, lower values of magnetisation and thermomagnetic coefficients. Table 4, Figs 7, Refs 13.