Quasicrystalline Thin Film Materials

Centrum Partners:

• Jens Birch, Lars Hultman and Igor Abrikosov (Linköping)

External Partners:

• Björgvin Hjörvarsson (Uppsala University)
• Sven Lidin and Osamu Terasaki (Stockholm University)

Industry partners

• Sandvik Materials Technology, Sandviken

Scientific Objectives

• Synthesis of amorphous metallic alloys and quasicrystalline material using magnetron sputtering and heat treatment.
• Studies of the evolution of the quasicrystalline phase during heat treatment.

Technology Transfer Objectives

• Patent/IPR
• Demonstrate the feasibility to deposit or thermally process a quasicrystaline thin film sputtered from a quasicrystaline target material
• Establish an associated industry and/or EU-projekt

Research plan:

Quasicrystals are binary or ternary metallic alloys of specific stoichiometry possessing long range order despite a lack of periodicity. Apart from the unusual structure, these materials show many anomalous and unique physical properties, most notably the fact that, unlike their constituent elements, they exhibit high hardness and stiffness and extremely low electrical and thermal conductivity. Furthermore, quasicrystals have stronger magnetic properties and exhibit greater elasticity at higher temperatures than crystals, and they are chemically inert and have a low friction and surface energy.

We will identify potentially significant materials and develop processes to deposit these in a form that optimizes their unique functionality. First quasicrystalline structures will be synthesized from known material systems. Quasicrystals have been found to be common structures in Al-based intermetallic alloys such as e.g. Al-Cu-Fe and Al-Ni-Co, and refractory metal Zr- and Ti-based alloys like Ti-Ni-Zr.

Amorphous binary/ternary metallic alloys (metallic glasses) will be synthesized using magnetron sputtering, either by co-sputtering from the individual elements or by sputtering from a compound target to obtain a stochiometric alloy. Short-period multilayers may also stabilize an amorphous phase with the interfaces. The feasibility to deposit or thermally process a quasicrystalline film sputtered from a quasicrystalline target will be demonstrated.

The films will be controllably annealed, and the process when the amorphous alloy/multilayer is transformed via quasicrystalline phases to the stable crystalline phases will be studied in detail. The evolution of quasicrystalline phases in the films is studied as a function of different related parameters such as the film thickness, annealing temperature and time, etc.

The annealing process will be studied using in-situ high-temperature X-ray diffraction (HT-XRD) in combination with differential scanning calorimetry (DSC) to investigate phase transformations together with TEM and EDX. The magnetic properties of the materials will be investigated. Experimental studies will be complemented in parallel with theoretical calculations to predict quasicrystalline phases, the formation thereof, their stability and physical properties.