Journal
NANO LETTERS
Volume 16, Issue 10, Pages 6207-6212Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.6b02467
Keywords
Thin films; hydrogen; phase transformation; STM; hydride phase; finite size effect
Categories
Funding
- Deutsche Forschungsgemeinschaft DFG [PU131/12-1]
- Heisenberg grant [PU131/9-2]
Ask authors/readers for more resources
Hydrogen uptake in metal hydrogen (M-H) nanosized systems (e.g., thin films, clusters) is both a fundamental and a technologically relevant topic, which is becoming more important due to the recent developments of hydrogen sensors, purification membranes, and hydrogen storage solutions. It was recently shown that hydrogen (H) absorption in nanosized systems adhered to rigid substrates can lead to ultrahigh mechanical stress in the GPa range. About -10 GPa (compressive) stress were reported for hydrogen loaded niobium (Nb) thin films. Such high stresses can be achieved when conventional stress-release channels are closed, e.g., by reducing the system size. In this paper, we demonstrate that the high stress can be used to strongly modify the system's thermodynamics. In particular, a complete suppression of the phase transformation is achieved by reducing the film thickness below a switchover value d(so). Combined in situ scanning tunneling microscopy (STM) and in situ X-ray diffraction (XRD) measurements serve to determine the switchover thickness of epitaxial Nb/Al2O3 films in the thickness range from 55 to 5 rim. A switchover thickness d(so) = 9 +/- 1 nm is found at T = 294 K. This result is supported by complementary methods such as electromotive force (EMF), electrical resistance, and mechanical stress measurements in combination with theoretical modeling.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available