Composites of Poly(3,4-ethylenedioxythiophene) and CoFe2O4 Nanoparticles: Composition Influence on Structural, Electrical and Magnetic Properties

MOLINA, FERNANDO VICTOR; ACHA, CARLOS; LANÚS MENDEZ ELIZALDE, MATÍAS; ANTONEL, PAULA SOLEDAD

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020 vol. 124 p. 6884 - 6895

1932-7447

Composites of magnetic CoFe 2 O 4 nanoparticles(MNP) in a poly(3,4-ethylenedioxythiophene) matrix at differentratios have been synthesized. Composites were characterized byelectron microscopy, X-ray diffraction, thermal analysis, electricalconductivity, magnetization, and magnetoresistance studies. In thecomposites the MNP appear clustered, with an interparticle distanceessentially constant, but where two regimes are distinguished forcluster separation: for high MNP concentrations an interclusterseparation similar to the interparticle distance is found, while for lowMNP contents the distance between clusters is larger than theinterparticle separation. The electrical conductivity increases withpolymer content, but being always far lower than general effectivemedium theory expectations. This indicates that the effect of MNPeffect on polymer conduction is probably related to the generation of mechanical stress both by introducing additional scatteringcenters and by producing different arrangement of the polymer chains, compared with the pure PEDOT. The magnetization studiesreveal the existence of the RKKY interaction, which couples ferromagnetically the MNP located in a cluster, while the dipolarinteraction dominates the interaction between clusters. Magnetoresistance was studied for these composites, with a maximum value close to 0.7% at 0.8 T for the lowest polymer content. The magnetoresistance correlates very well with the reversible part of themagnetization, indicating that its possible origin should be associated with polymer mechanical deformation due to the magnetic-field-induced rotation of the MNP.