Graduate Thesis Or Dissertation
 

Soft Magnetic Composites for High Frequency Applications

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/z603r202j

Descriptions

Attribute NameValues
Creator
Abstract
  • Soft magnetic composites, consisting of fine metallic particles in a non-magnetic, insulating matrix, have great potential for integrated inductor and antenna applications. The dielectric and magnetic properties of soft magnetic composites can be tailored by the choice of matrix as well as particle composition, size, and concentration for reduction in device footprint and improvement in performance. In particular, unlike conventional single-phase materials, magnetic anisotropy in the composites can be controlled by choice of particle shape and alignment to overcome the Snoek's limit, enabling both high permeability and high ferromagnetic resonance frequency. To develop a soft magnetic composite with 1) high permeability, 2) high ferromagnetic resonance frequency, 3) low hysteresis loss, and 4) low eddy current loss, material design considerations are first examined in terms of magnetic particle design and matrix design. The effects of constituent particle shape and alignment, volume fraction, and composite shape on microstructural and magnetic properties are studied in Ni-Fe microdisk composites and NiFe₂O₄ nanocomposites. The total magnetic anisotropy of the composites is determined by the sometimes-competing influences of composite demagnetizing field and particle shape anisotropy. To lift the Snoek's limit and obtain simultaneous high permeability and high ferromagnetic resonance frequency, planar magnetic anisotropy is introduced to the composites by aligning the shape anisotropy of individual Ni-Fe microdisks in an in-plane rotating field. This planar alignment process is investigated by a systemic experimental and theoretical study of magnetic disk rotation in a Newtonian fluid, which yields insights necessary for both alignment process optimization and magnetic anisotropy fine-tuning. Finally, the magnetic alignment process is integrated to an inkjet printer, and magnetic samples with arbitrary aligned anisotropy are demonstrated by printing a magnetic nanoparticle bearing ink.
License
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details SongHan2015.pdf 2017-08-23 Public Download