PhD position - High-Entropy Alloy Refractory Thin films for Hydrogen storage

13 Feb 2024
Job Information

Organisation/Company

LSPM , CNRS 3407

Research Field

Physics » Condensed matter properties
Engineering » Materials engineering
Physics » Applied physics
Physics » Acoustics
Physics » Solid state physics
Engineering » Microengineering

Researcher Profile

First Stage Researcher (R1)

Country

France

Application Deadline

31 Mar 2024 - 23:00 (Europe/Paris)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

35

Offer Starting Date

1 Oct 2024

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

A fully funded 3 years PhD project is available between the Laboratoire des Sciences des Procédés et des Matériaux (LSPM/USPN) and Institut Pprime (Univ. Poitiers) in collaboration with the Materials and process engineering lab. (IMaP/UCL).

Short description of the thesis project: In the context of greenhouse gas reduction, the safe and compact storage of hydrogen (H) becomes of strategic significance. Compared to conventional methods of H storage in the gas or liquid-form, solid-state H storage in the form of metal hydrides (MH) represents the most compact and safest technology [1], as it avoids the handling at high pressure (up to 700 bar) or at very low temperatures (-253°C). In addition, the solid storage of H offers high volumetric capacity (60 kg/m3) and is a reversible process with adsorption/desorption cycles occurring at low pressures (Pmax = 30 bar) and temperatures (absorption/release T < 400 °C) [1]. Recently, refractory high entropy alloys (RHEAs) with cubic structure (bcc), have gained interest for their great potential as H storage material since they can absorb and release up to 2.7 wt%. of H, which results in one of the highest H/M ratios (up to 2.5) [2,3]. In addition, the vast composition space offered by these new alloys (constituted by ≥4 elements), can be exploited to optimize the performance of H storage, in terms of gravimetric capacity, temperature and sorption/desorption kinetics, reversibility and cyclability.

The studies on RHEAs for H-storage have focused on bulk materials [2,3], with limited focus on thin films (TFs) counterparts. This approach has the advantages to easily explore the large compositional space offered by multicomponent HEA by co-sputtering from individual metal targets, managing to quickly identifying promising composition for H storage. Moreover, TFs offer the possibility to obtain unique microstructures (i.e. with tunable nanoporosity or grain size) capable to comply with volume expansion during H-sorption as well as to play with lattice distortion due to differences in atomic radii of the constitutive metal species, with potential to improve the H uptake capability.

However, the hydrogenation phenomena occurring in TF-HEAs – involving the H absorption/desorption process, the formation of metallic hydrates (MH) – is still to be uncovered in such complex alloys, since it requires the implementation of advanced scale-bridging characterization techniques (from the m down to the nm scale) capable to grasp the intricate interconnection with the atomic/microstructural and hydrogenation process. This is even more challenging in the case of TF-HEAs characterized by small volumes (micrometer scale), requiring the need of advanced techniques sensitive at such small scales and able to monitor the hydrogenation process.

In this context, the proposed PhD project will focus on the deposition and structural characterization of TF-HEAs (Pprime) with a fixed ternary TiZrHf (elements characterized by high H storability) base system, while investigating the addition of Ta, V or Mo with the aim to explore the hydrogenation process, identifying the effect of the single elemental addition (Fig. 1a). The hydrogenation tests (LSPM) will be conducted under diverse conditions, Pmax = 30 bar and T<400 °C and cyclic behavior. Simultaneously, advanced microscale mechanical characterization (LSPM) will be carried out by optoacoustic techniques (Picosecond Ultrasonics and Brillouin Light Scattering) and in situ scanning electron microscope (SEM) nanoindentation (Fig. 1b). This integrated approach aims to elucidate the processes of H absorption and the subsequent formation of metal hydrides (MH). Both techniques can be carried out in situ varying the temperature (~800 °C) unveiling the MH dissolution/desorption process, which will be compared with the results of in situ wafer curvature experiments (Pprime).

The collaboration with IMaP (UCL, Be) will enable to exploit high resolution transmission electron microscopes (HRTEM) in order to explore at the nanoscale the hydrogenation and the formation of MH (Fig. 1c). Finally, upon having optimized the composition, novel TF-RHEAs architectures will be explored (i.e. nanoporous, with high lattice distortion) in order to further improve the gravimetric capacity, while ultimately controlling the conditions of H absorption-release. Overall, the results of the PhD will pave the way to understanding fundamental questions involving the hydrogenation mechanisms in TF-RHEAs, opening new scenarios for the design of new materials with high H storage performances with clear impact for the present green transition.

Your tasks:

• Synthesis and structural characterization of TF-RHEAs (TiZrHf +Ta/V/Mo) by magnetron sputtering with controlled composition and morphology (Pprime).
• Hydrogenation and micromechanical characterization with advanced in situ techniques (LSPM).
• Advanced structural characterization with HRTEM (IMaP).
• Unveiling the interplay among atomic/micro structure ↔ Hydrogenation process ↔ mechanical properties, leading to a new class of materials with potential applications (Pprime/LSPM/IMaP).

The offer:

• Multidisciplinary project covering physics, materials science, mechanics, and nanotechnologies.
• Development of cutting-edge experimental tools for the synthesis of TF-HEAs and advanced scale-bridging characterizations.
• Multicultural and dynamic laboratory environment within two labs in France and a collaborative partner in Belgium. High mobility and competitive salary.
• National and International collaboration network with different institutions in France and Europe.

Your Profile:

• Master’s degree in physics or materials science or similar disciplines.
• For students without a master, a master (M2) internship can also offered with graduation expected before October 2024 followed by the enrollment in the PhD program.

Further information & application: For further information and application please send your CV and your exam scores (Bachelor and Master) to Prof. Gregory Abadias ([email protected] ), Dr. Matteo Ghidelli ([email protected] ), Dr. Martin Robin ([email protected] ).

References: [1] M. Hirscher et al., J. Alloys Compound. 827, 153548 (2020). [2]. F. Marques et al., Energy Environ. Sci. 14, 5191–5227 (2021). [3] L. Kong et al., Frontiers in Materials 10, 1135864 (2023).

Requirements

Research Field

Engineering » Materials engineering

Education Level

Master Degree or equivalent

Research Field

Engineering » Microengineering

Education Level

Master Degree or equivalent

Research Field

Physics » Solid state physics

Education Level

Master Degree or equivalent

Research Field

Physics » Condensed matter properties

Education Level

Master Degree or equivalent

Research Field

Physics » Acoustics

Education Level

Master Degree or equivalent

Research Field

Physics » Applied physics

Education Level

Master Degree or equivalent

Languages

ENGLISH

Level

Good

Languages

FRENCH

Additional Information
Work Location(s)

Number of offers available

1

Company/Institute

Université de Poitiers, Université Sorbonne Paris Nord

Country

France

Geofield

Where to apply

E-mail

[email protected]

Contact

State/Province

Ille de France

City

Villetaneuse

Website

http://www.lspm.cnrs.fr/?lang=fr

Street

99 Avenue JB Clement,

Postal Code

93430

STATUS: EXPIRED