Thin Film Synthesis and Characterization of New MAX Phase Alloys
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
The objective of this Thesis is synthesis and characterization of new MAX phase alloys (M = early transition metal, A = A-group element, and X = C or N) based on incorporation of M and X elements previously not used in any known MAX phases. This is motivated by a search for optimized and unique materials properties, such as different magnetic states.
Two synthesis routes have been used to attain Ti2AlC1-xOx: deposition of Ti2AlCy under high vacuum conditions with residual gas acting as O source, and solid-state reactions following deposition of understoichiometric TiCy on Al2O3. Detailed local quantification by analytical transmission electron microscopy (TEM) including electron energy loss spectroscopy (EELS) shows up to 13 at.% O within high quality MAX phase structure. According to previous theoretical work, the range of experimentally obtained O content is enough to observe drastic changes in the materials anisotropic electronic properties. Calculations on effect of substitutional O on shear deformation have also been performed.
In a recent theoretical study by Dahlqvist et al., (Cr,Mn)2AlC has been predicted as a new stable magnetic nanoscale laminate. Inspired by this work, thin films of (Cr,Mn)2AlC, as well as of a neighboring system (Cr,Mn)2GeC, have been synthesized by magnetron sputtering. Incorporation of 8 and 12.5 at.% of Mn, respectively, has been detected by analytical TEM including EELS and energy dispersive X-ray spectroscopy (EDX). The total saturation moment of 0.36μB per Mn atom at 50 K has been measured by vibrating sample magnetometry (VSM) for a (Cr,Mn)2GeC sample, providing the first experimental evidence of a magnetic MAX phase.
The experimental results obtained in this Thesis provide a base for expanding the MAX phase definition and materials characteristics into new areas, towards further fundamental understanding and functionalization.
Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. , 37 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1538
IdentifiersURN: urn:nbn:se:liu:diva-77775Local ID: LIU-TEK-LIC-2012:23ISBN: 978-91-7519-868-2OAI: oai:DiVA.org:liu-77775DiVA: diva2:529126
2012-06-14, Jordan-Fermi, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Rosén, Johanna, Dr.Hultman, Lars, Professor
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