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Title: Formation of metallic overlayers on quasicrystal surfaces
Author: Wearing, Lisa Helen
ISNI:       0000 0004 2670 7848
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2008
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The main aim of this study is to explore the fundamentals of aperiodicity through the deposition of a single elemental aperiodic overlayer onto a quasicrystal surface. The main difficulty with understanding the effects of aperiodicity on the quasicrystal structure arises due to the chemical complexity associated with the surface, as such structures are only observed in metallic alloys containing two or more elements. The formation of a single element quasicrystalline structure has been achieved through the deposition of Pb on i-AI-Pd-Mn and d-AI-Ni-Co (results of the latter not included). This includes an initial study of the effects of aperiodicity on the electronic properties of the surface and the conclusion that the formation of a pseudogap at the Fermi level is due to the aperiodicity of the quasicrystalline structure and not the chemical complexity of the system. The effects of aperiodicity on the magnetic properties of such a system are not yet known, in particular for a single magnetic species which is ordered aperiodically. For this reason Fe was deposited onto two different quasicrystalline surfaces. They show the formation of such a quasiperiodic magnetic film was not observed, the Fe was in fact aligned periodically along the high symmetry axes of the substrates. This result, along with other work in the same field provides some guidance as to which atoms have the greatest chance of ordering aperiodically. Most of the research within the field involves thin film deposition in ultra high vacuum. This is a costly technique, and if films on quasicrystal surfaces were one day to be exploited by industry then production would be severely limited. It is for this reason that the electrochemical deposition of Cu onto AI-Pd-Mn has been studied. This work provides the starting point for further study into the electrochemical deposition on to the quasicrystal surface and comparison to those studies in Ultra Right Vacuum (URV).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral