Size- and Composition-Dependent Radio Frequency Magnetic Permeability of Iron Oxide Nanocrystals

Journal Article · Sun Nov 30 23:00:00 EST 2014 · ACS Nano

DOI:https://doi.org/10.1021/nn504711g· OSTI ID:1211208

Yun, H; Liu, XY; Paik, T; Palanisamy, D; Kim, J; Vogel, WD; Viescas, AJ; Chen, J; Papaefthymiou, GC; Kikkawa, JM; Allen, MG; Murray, CB

We investigate the size- and composition-dependent ac magnetic permeability of superparamagnetic iron oxide nanocrystals for radio frequency (RF) applications. The nanocrystals are obtained through high-temperature decomposition synthesis, and their stoichiometry is determined by Mossbauer spectroscopy. Two sets of oxides are studied: (a) as-synthesized magnetite-rich and (b) aged maghemite nanocrystals. All nanocrystalline samples are confirmed to be in the superparamagnetic state at room temperature by SQUID magnetometry. Through the one-turn inductor method, the ac magnetic properties of the nanocrystalline oxides are characterized. In magnetite-rich iron oxide nanocrystals, size-dependent magnetic permeability is not observed, while maghemite iron oxide nanocrystals show clear size dependence. The inductance, resistance, and quality factor of hand-wound inductors with a superparamagnetic composite core are measured. The superparamagnetic nanocrystals are successfully embedded into hand-wound inductors to function as inductor cores.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: AR0000123
• OSTI ID: 1211208
• Journal Information: ACS Nano, Journal Name: ACS Nano Journal Issue: 12 Vol. 8; ISSN 1936-0851
• Country of Publication: United States
• Language: English