Sonochemical synthesis and characterization of FeCo nanoparticles

Soft magnetic NPs have gained a lot of attention during the last decades because of their possible application in high performance exchange-spring permanent magnets. In this regards the FeCo alloys represent the most interesting NPs materials and several chemical strategies have been successfully explored with the aim to control composition, morphology, size and magnetic properties. Only recently acoustic cavitation (sonochemistry) has been proposed for the synthesis of FeCo alloys leading mostly to formation of amorphous NPs in the case of primary sonochemistry.[1] I n the present work we present our approach based on a modified surfactant-free polyol process promoted by secondary sonochemical synthesis suitable for formation of nanocrystalline materials. XRD analysis of the obtained black precipitate revealed formation of nanocrystalline FeCo alloy. The isolated material showed a maximum saturation magnetization of 200 emu/g and extremely low coercivity. TEM and HRTEM analysis showed formation of cubic nanocrystalline FeCo NPs with size distribution in the range of 10 - 200 nm as expected in absence of confining media during reaction. This study has been supported by the European IRSES NANOMAG Project. REFERENCES [1] K.S. SUSLICK, T. HYEON, M. FANG, Chem. Mater. 8, 2172 (1996)