Speaker
Description
Medium-temperature baking (Medium-T Baking) has emerged as a key technique for enhancing SRF cavity performance, with multiple studies attributing its efficacy to oxide decomposition and oxygen diffusion. In-situ high-resolution transmission electron microscopy (HRTEM) enables real-time, atomic-scale visualization of dynamic structural changes, providing an ideal platform for probing Nb oxide layer dynamics during baking.
Our previous in-situ HRTEM measurements at 350 °C heating showed emergent 'white dots' and local contrast variations that revealed nanoscale lattice transformations. Recently, we utilized on-site vacuum storage to avoid cross-section sample oxidation post-FIB processing, which enabled us to single out the oxide layer for both HRTEM and energy-dispersive X-ray spectroscopy (EDS) to obtain definitive evidence of its decomposition during heating. We also detected interstitial oxygen diffusion-induced lattice defects via HRTEM.
Preliminary results showed that the observed defects may enhance cavity performance, and further vertical tests are underway to fully elucidate the underlying mechanisms.
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