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Investigation of electrical and magnetic properties of nanoparticles and nanofibers with the aim to tailor material properties of nanocomposites

Anna Jänis (Institutionen för material- och tillverkningsteknik)
Göteborg : Chalmers University of Technology, 2008. - 26 s.
[Licentiatavhandling]

Nanocomposites are the subject of interest in this study which can be explained by the factum that using building blocks with dimensions in the nanosize range makes it possible to design and create new materials which can satisfy several functions at the same time for many applications. The applications of interest in this study belong to the microwave frequency region and for that reason a number of materials were investigated to define their microwave absorbing properties. The aim is to tailor material properties of nanocomposites by using fillers with different electromagnetic properties. Two types of filler were investigated during the study: fillers with electrical- and magnetic-field losses. Among fillers with electrical-field losses SiC nanowires were investigated together with SiC microcrystalline particles. The results presented in this study show that fillers in form of particles and fibers of nanometer size introduce higher level of energy loss in comparison with micrometer sized particles and fibers. It has also been found that in the case of SiC nanowires the higher carbon content introduces higher level of electrical-field losses. Among fillers with magnetic-field losses manganese-ferrite (soft) and cobalt-ferrite (hard) nanoparticles were investigated. The results show that soft and hard magnetic ferrites have absorbing properties in different frequency regions. Thus, manganese- and cobalt-ferrite nanoparticles can be used together to achieve absorption in a wide frequency band. To achieve higher magnetic-field losses in the composite, the nanoparticles with higher initial permeability and lower coercivity are preferable as filler. To connect microwave properties of nanoparticles/nanofibers and nanocomposites to their microstructure two types of materials characterization were always performed: microstructural characterization by applying optical and electron microscopy and characterization in microwave region using an Automatic Network Analyzer (ANA).

Nyckelord: nanocomposite, microwave absorbing properties, SiC, nanowire, nanoparticle, ferrite, microscopy, network analyzer



Denna post skapades 2008-05-21.
CPL Pubid: 71124

 

Institutioner (Chalmers)

Institutionen för material- och tillverkningsteknik

Ämnesområden

Materialteknik
Funktionella material

Chalmers infrastruktur

Relaterade publikationer

Inkluderade delarbeten:


Characterization and dielectric properties of beta-SiC nanofibres


Spectroscopic ellipsometry and vector network analysis for determination of the electromagnetic response in two wavelength regions


Microwave absorbing properties of ferrite-based nanocomposites


Examination

Datum: 2008-06-12
Tid: 11:00
Lokal: Omega, Hörsalsvägen 7, Chalmers
Opponent: Daniel Sjöberg, Department for Electrical and Information Technology, Lund University, Sweden

Ingår i serie

Technical report - Department of Materials and Manufacturing Technology, Chalmers University of Technology 1652-8891