title: Polymer nanocomposites exhibiting magnetically tunable microwave properties.
abstract: Polymer nanocomposites (PNCs) have been synthesized using Rogers polymer and CoFe₂O₄ nanoparticles (CFO NPs). X-ray diffraction (XRD) confirms the inverse spinel crystal structure of CFO NPs and transmission electron microscopy (TEM) images show the uniform dispersion of nanoparticles (10 nm ± 1) into the polymer matrix. Magnetic measurements indicate superparamagnetic response near room temperature for all PNCs. A blocking temperature T(B)~298 K was observed and does not vary for different loading fractions of CFO NPs for the PNCs. The saturation magnetization (M(s)) was found to be 11 emu g⁻¹ for 30 wt% CFO, increasing to 32 emu g⁻¹ for the 80 wt% CFO loaded PNC. A large value of coercivity (H(c) = 19 kOe) is also observed at 10 K and is not affected by varying CFO loading. Microwave measurements show significant absorption in the 80 wt% CFO loading PNC and the quality factor shows a strong enhancement with applied magnetic field.
authors.affiliation: Integrated Functional Materials Group, Department of Physics, University of South Florida, Tampa, FL 33620, USA.
authors.forename: K
authors.initials: K
authors.lastname: Stojak
authors.forename: S
authors.initials: S
authors.lastname: Pal
authors.forename: H
authors.initials: H
authors.lastname: Srikanth
authors.forename: C
authors.initials: C
authors.lastname: Morales
authors.forename: J
authors.initials: J
authors.lastname: Dewdney
authors.forename: T
authors.initials: T
authors.lastname: Weller
authors.forename: J
authors.initials: J
authors.lastname: Wang