Optimized magnetodielectric coupling on high-temperature polymer-based nanocomposites

CoFe2O4 (CFO) ferrite nanoparticles with an average size of 15 nm were synthesized by a hydrothermal method and used to develop magnetodielectric (MD) composites with the piezoelectric diamine 2CN/diamine 0CN as polymer matrix . It is shown that the dielectric constant, dielectric loss, and saturation magnetization values of the composites increase with the increasing CFO content, being 4.4, 0.01, and 12 emu.g-1, respectively, for the sample with 20 weight percentage (wt.%) of ferrite. Additionally the large MD response (MD (%)=10.15 and magnetodielectric coefficient (γ)=5.8x10-2) demonstrates the effective magneto-mechano-electrical interaction between magnetostrictive CFO and the polymer matrix. Such high MD response, the highest reported for polymer-based composite materials, can support innovative applications in the areas of sensors, actuators, and filters, among others.The authors thank the Portuguese Fundação para a Ciência e Tecnologia (FCT) for financial support under project PTDC/EEI-SII/5582/2014 and in the framework of the Strategic Funding UID/FIS/04650/2013. P. Martins acknowledges also support from FCT (SFRH/BPD/96227/2013 grant). Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry Department under the ELKARTEK Program is also acknowledged.