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PhD in New Materials for optical pplications in the mid-infrared (M/F)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : mardi 25 mai 2021

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General information

Reference : UPR3079-MATALL-001
Workplace : ORLEANS
Date of publication : Tuesday, May 04, 2021
Scientific Responsible name : Mathieu ALLIX
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

This PhD is part of the ANR project HEMERALD (High Efficiency of Massive Emitting ceRAmic for the 1.7-2.7 μm LASER winDow) which aims at developing new transparent ceramics (Ga2O3-Nb2O5- RE2O3 systems) for LASER applications in the 1.7-2.7 μm optical window.
An innovative synthesis process, aerodynamic levitation coupled to laser heating, was chosen to explore the phase diagrams and identify new crystal phases and glassy domains. Structural and spectroscopic characterisations will be performed on these new materials. Selected compositions will then be synthesised and shaped. The activities of this thesis will be shared between the CEMHTI (Orléans) and ICMCB (Bordeaux) laboratories.

Scientific context :
The CEMHTI laboratory (CNRS UPR3079) is pioneer in the use of aerodynamic levitation (ADL) coupled with laser heating to synthesize glassy or molten precursors of various compositions that will be crystallized directly upon cooling from the supercooled liquid or at relatively low temperatures in the case of glasses to produce dense oxide ceramics with new compositions, crystal structures and/or microstructures that exhibit optical emissions in the mid-infrared (http://www.cemhti.cnrs-orleans.fr/instruments/levitation.aspx).

Using this approach, we have, for example, recently isolated new luminescent YAG materials with extraordinary non-stoichiometric compositions (European patent application No. 21305159.2; manuscript in preparation). In parallel to ADL, this project will extend the concept of glass/molten liquid crystallisation synthesis by using mechanical activation methods (e.g. high energy ball milling) to produce amorphous precursors at low temperatures, thus providing access to a wider range of compositions. This PhD position is funded by the ANR project "HEMERALD".

Desired profile of the candidate:
The candidate must have a Master's degree in materials science/solid state chemistry. He/she should also have a solid background in solid state chemistry and knowledge (theoretical and/or practical) in characterization techniques (X-ray diffraction, electron microscopy, spectroscopy...). The successful candidate will join a team of international PhD students/post-docs/engineers and may have the opportunity to travel to access specific expertise and facilities. The University of Orléans also offers teaching experience. Start of the thesis desired in October 2021.

Selected recent publications from the team:
"Highly non-stoichiometric garnet ceramics for optical function", European Patent Application N° 21305159.2 (2021)
"La2Ga3O7.5: A metastable ternary melilite with a super-excess of interstitial oxide ions synthesized by direct crystallization of the melt", Chemistry of Materials (2020) doi.org/10.1021/acs.chemmater.0c03441
"Cooperative mechanisms of oxygen vacancy stabilization and migration in the isolated tetrahedral anion Scheelite structure", Nature Communications (2018) doi.org/10.1038/s41467-018-06911-w
"Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics", Nature Communications (2018) doi.org/10.1038/s41467-018-03467-7

Deadline for receipt of applications is 25 May 2021

Work Context

CEMHTI is a CNRS research unit spread over two nearby sites (High Temperature and Cyclotron) and employing about 110 people.

The laboratory develops original expertise and tools on a national and international level to study the physico-chemical properties of materials under extreme conditions.
The PhD student will be based at the high temperature site of the laboratory, will join the team Innovative (Glass-)ceramics: crystallisation, structure and corrosion and will report to the team leader.

The thesis will be carried out between the CEMHTI laboratory in Orléans and the ICMCB laboratory in Bordeaux.

Equipment available:
The CEMHTI laboratory has excellent equipment for the synthesis and structural characterisation of glass-ceramic and ceramic materials. These include:
- Aerodynamic levitation coupled with CO2 laser heating.
- X-ray powder diffraction (in-situ measurements up to 2000°C possible).
- Scanning electron microscopy (FEG SEM coupled with EBSD)
- Ultimate resolution transmission electron microscopy.
- High temperature infrared and Raman spectroscopy.
- High field and high temperature solid state NMR spectroscopy.

Constraints and risks

Travel in France and abroad is to be expected to promote the progress of the thesis or to participate in conferences.

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