Oxygen diffusion in freestanding body centered cubic tantalum structural thin films in air and in high vacuum

• DOI: 10.1016/j.tsf.2024.140392
• Publication Date: 2024-05-31T07:06:30Z
• Authors: Ryan M. Pocratsky; Md. Shariful Islam; Longchang Ni; Eli J. Fox; Maarten P. de Boer

Sensors and actuators constructed from freestanding tantalum thin films show promise for micromachining applications the study of film mechanical behavior. To assess this promise, it is necessary to gain further understanding performance Ta as a structural material. We first coefficient thermal expansion, αTa, using micromachined bent beams, which amplify displacement compared linear expansion. The value αTa 6.8•10−6 m/m°C, in good agreement with bulk value. This validation enables interstitial oxygen diffusion Ta, literature values activation energy vary widely, 0.60 1.98 eV. Displacement air due becomes measurable after 30 min exposure at 180°C. extract an 0.53 eV/atom. Analysis indicates that lattice rather than grain boundary associated mechanism. inhibit oxidation, we construct stage controls specimen temperature 10−5 Pa vacuum. Then, 24 h hold, oxidation suppressed up 400°C. result discussed terms O dissolution its native oxide, coupled absorption background gases.