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a research group of the department of Solid State Sciences, Ghent University


November 2011 - October 2015

BOF - 2/4 years project D. Depla and W.P. Leroy

MAPCONDUCT : A multi-axis approach to elucidate the conduction mechanism of thin film solid state electrolytes.

The project goal is to modify the composition of the thin film solid state electrolytes (axis 1), to vary the deposition conditions (axis 2) and to measure the ion conductivity of solid state electrolytes (axis 3). The result of this multi-axis approach is a 3D view which allows to pinpoint the parameters influencing the conduction mechanism of thin film solid state electrolytes.

This project is funded by the Special Research Fund (BOF) of Ghent University, as a cooperation between prof. D. Depla (UGent - DRAFT, promotor) and prof. A. Adriaens (UGent - ESA, co-promotor), with prof. A. Hubin (VUB - SURF) as external researcher.
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The conduction mechanism of thin film solid state electrolytes

  January 2012 - December 2015

D. Depla and A. Hubin (VUB)

The materials which play the central role in this project are electrically conductive due to the presence of mobile ions. To reach a high enough conductivity, these materials, so-called solid state electrolytes, are used at high temperature. To reduce the application temperature, the film thickness can be decreased. However, some well-known relationships connecting ion conductivity to crystallinity and composition, derived for bulk and thick film materials, become questionable when reducing the thickness to 1 µm and less. The goal of the research project is to investigate the parameters which influence the ion conductivity of thin films. To deposit these thin films reactive magnetron sputtering will be used. This technique allows to modify the morphology and composition in a flexible way. This opens the possibility to produce thin film samples with a broad spectrum of properties influencing the ion conductivity. The influence of composition and morphology will not only be investigated on the global ion conductivity but also at the nanometer scale. To reach this goal a new AFM based diagnostic tool to measure the local impedance will be developed. This fundamental research will enable to propose new routes to materials with high ion conductivity.
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BIANCO : Biaxially aligned complex oxides

  January 2014 - December 2017

D. Depla and W.P. Leroy

In a single crystal, the atoms are periodically arranged in space. Polycrystalline materials are assemblies of single crystals. The orientation of the constituent crystals in a polycrystalline material can be random, but the crystals can also be aligned according to one or more axes. Within a polycrystalline thin film, the crystals are typically oriented according to the substrate normal, but depending on the deposition conditions biaxial alignment is also possible. In the latter case, the crystals are not only oriented according to the substrate normal, but also have the same in-plane orientation. This research project focuses on the understanding of the mechanisms of biaxial alignment during thin film deposition as this assists in the unravelling of the fundamental aspects of thin film growth. This research goal will be tackled by combining different types of modelling (Molecular Dynamics and Monte Carlo) with experimental work using magnetron sputtering as deposition technique. This versatile deposition technique allows to deposit not only simple materials but also materials with a complex composition. By biaxially aligning the crystals of complex material thin films the project BIANCO can be seen as an important step towards an alternative synthesis route for single crystal thin films.
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QUOTAS : Quantification of target surfaces

  January 2014 - December 2017

D. Depla and B. Partoens (UAntwerpen)

Modelling of plasma based deposition techniques can give an atomistic view on the important driving processes, and in this way assist in steering these processes. This atomistic view however becomes blurred due to the lack of reliable input parameters. For magnetron sputter deposition, a technological relevant plasma based deposition technique, this boils down to knowledge of two parameters at the source level: the yield of sputtered atoms, and the yield of emitted secondary electrons. The values of these parameters are strongly defined by the surface condition of the source material, the so-called target. Currently, there is only limited fundamental research on the target surface condition during magnetron sputtering. This project will build a specific set-up to measure the target condition using X-ray photoelectron spectroscopy, a technique which allows to retrieve chemical information of the first nanometres of the target surface. The information obtained with this technique will be used as starting point to calculate the sputter yield and the electron yield. The sputter yield will be computed using existing Monte Carlo software, while the electron yield will be calculated using first principles techniques. This combination of in-depth characterisation of the target surface and high level calculations is a unique strategy to reach fundamental knowledge about magnetron sputter deposition.
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ENCLOSE : An embedded network of sensors in composites for local sensing

  January 2015 - December 2020

J. Degrieck, I. Vandriessche, P. Smet and D. Depla

The project ENCLOSE focuses on the detection of damage in structural composites by specially developed sensors. Two classes of sensors are envisaged. The first class is based on an electrical output (strain gauge en piezoelectric materials). The second group uses mechanoluminescent materials. The sensors are produced by reactive sputter deposition, inkjet printing and solid state synthesis.
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SPADONA : Sputter and arc deposition of new alloys.

  January 2016 - December 2018

D. Depla, R. Franz

The present project will study the synthesis of high entropy alloy (HEA) thin films by physical vapour deposition (PVD). HEAs are metallic compounds containing 5 or more metallic elements in approximately equimolar ratios, e.g. AlCoCrCuFeNi. Several studies on bulk HEAs were already published, but as thin films they are only scarcely investigated. Using PVD for synthesis offers possibilities to control the microstructure of the HEAs that are not available for common bulk synthesis methods. For the current project, two different PVD techniques will be applied, magnetron sputtering and cathodic arc deposition, offering different synthesis conditions. A combination of high-level thin film and plasma characterisation will provide new insights in the compositional and processing influence on the structure and functional properties such as electrical resistance, hardness and tribological behaviour of HEA thin films. The expected results will contribute to setting-up a three dimensional structure zone model that describes the microstructure as a function of the available energy per arriving atom during thin film growth and the composition, with a link to the functional properties. The use of different PVD techniques will provide a more general picture of the synthesis-structure-property relations than common research approaches applying only a single technique. To ensure a successful execution of the planned investigations, two research groups with profound experience in PVD of thin films and coatings will combine their expertise. The group Design, Research, Applications and Feasibility of Thin films from Ghent University in Belgium will use magnetron sputtering to deposit the HEA thin films, whereas the group Functional Materials and Materials Systems from Montanuniversität Leoben in Austria will apply cathodic arc deposition. Besides specialised expertise in plasma analysis and thin film synthesis and characterization from each group, also common experience will be utilised to ensure a high quality of the results, e.g. by round-robin tests during the cooperative project. In summary, the general objective of the proposed project is well reflected by the meaning of its acronym SPADONA (old Italian word for longsword): cutting edge research on a new type of alloys.