Microwave-assisted solution synthesis, microwave sintering and magnetic properties of cobalt ferrite

[EN] A simple, soft, and fast microwave-assisted hydrothermal method was used for the preparation of nanocrystalline cobalt ferrite powders from commercially-available Fe(NO3)(3)center dot 9H(2)O, Co(NO3)(2)center dot 6H(2)O, ammonium hydroxide, and tetrapropylammonium hydroxide (TPAH). The synthesis was conducted in a sealed-vessel microwave reactor specifically designed for synthetic applications, and the resulting products were characterized by XRD, FE-SEM, TEM, and HR-TEM. After a systematic study of the influence of the microwave variables (temperature, reaction time and nature of the bases), highly crystalline CoFe2O4 nanoparticles with a high uniformity in morphology and size, were directly obtained by heating at 130 degrees C for 20 min using the base TPAH. Dense ceramics of cobalt ferrite were prepared by non-conventional, microwave sintering of synthesized nanopowders at temperatures of 850-900 degrees C. The magnetic properties of both the nanopowders and the sintered specimens were determined in order to establish their feasibility as a permanent magnet. This work has been carried out with financial support from the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) and CSIC through the Projects MAT2015-67586-C3-R and NANOMIND, respectively. A. Borrell acknowledges MINECO for a Juan de la Cierva contract (IJCI-2014-19839). Fariñas, JC.; Moreno, R.; Pérez, A.; García, MA.; García-Hernández, M.; Salvador Moya, MD.; Borrell Tomás, MA. (2018). Microwave-assisted solution synthesis, microwave sintering and magnetic properties of cobalt ferrite. Journal of the European Ceramic Society. 38(5):2360-2368. https://doi.org/10.1016/j.jeurceramsoc.2017.12.052