TY - JOUR
T1 - The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption
AU - Verma, Neha
AU - Delhez, Rob
AU - van der Pers, Niek M.
AU - Tichelaar, Frans D.
AU - Böttger, Amarante J.
PY - 2021
Y1 - 2021
N2 - 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.
AB - 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.
KW - Deformations
KW - Intermediate layer
KW - Microstructure
KW - Pd thin film
KW - Phase transitions
KW - X-ray diffractions
UR - http://www.scopus.com/inward/record.url?scp=85095954848&partnerID=8YFLogxK
U2 - 10.1016/j.ijhydene.2020.10.163
DO - 10.1016/j.ijhydene.2020.10.163
M3 - Article
AN - SCOPUS:85095954848
SN - 0360-3199
VL - 46
SP - 4137
EP - 4153
JO - International Journal of Hydrogen Energy
JF - International Journal of Hydrogen Energy
IS - 5
ER -