The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

Verma, N.; Delhez, R.; van der Pers, N.M.; Tichelaar, F.D.; Bottger, A.J.

doi:10.1016/j.ijhydene.2020.10.163

The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

Title

The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

Author

Verma, N. (TU Delft Team Amarante Bottger)
Delhez, R. (TU Delft Team Amarante Bottger)
van der Pers, N.M. (TU Delft Team Amarante Bottger)
Tichelaar, F.D. (TU Delft QN/Afdelingsbureau; Kavli institute of nanoscience Delft)
Bottger, A.J. (TU Delft Team Amarante Bottger)

Date

2021

Abstract

In this work, we studied the mechanical and thermal stability of ~100 nm Pd thin films magnetron sputter deposited on a bare oxidized Si(100) wafer, a sputtered Titanium (Ti) intermediate layer, and a spin-coated Polyimide (PI) intermediate layer. The dependence of the film stability on the film morphology and the film-substrate interaction was investigated. It was shown that a columnar morphology with elongated voids at part of the grain boundaries is resistant to embrittlement induced by the hydride formation (α↔β phase transitions). For compact film morphology, depending on the rigidity of the intermediate layer and the adherence to the substrate, complete transformation (Pd-PI-SiO₂/Si) or partly suppression (Pd-Ti-SiO₂/Si) of the α to β-phase was observed. In the case of Pd without intermediate layer (Pd-SiO₂/Si), buckling delamination occurred. The damage and deformation mechanisms could be understood by the analysis of the stresses and dislocation (defects) behavior near grain boundaries and the film-substrate interface. From diffraction line-broadening combined with microscopy analysis, we showed that in Pd thin films, stresses relax at critical stress values via different relaxation pathways depending on film-microstructure and film-substrate interaction. On the basis of the in-situ hydriding experiments, it was concluded that a Pd film on a flexible PI intermediate layer exhibits free-standing film-like behavior besides being strongly clamped on a stiff SiO₂/Si substrate.

Subject

Deformations
Intermediate layer
Microstructure
Pd thin film
Phase transitions
X-ray diffractions

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http://resolver.tudelft.nl/uuid:5c62fe35-f42a-49ee-9bb8-991039426d8f

DOI

https://doi.org/10.1016/j.ijhydene.2020.10.163

ISSN

0360-3199

Source

International Journal of Hydrogen Energy, 46 (5), 4137-4153

Part of collection

Institutional Repository