%0 Journal Article
%A Zaidman, Artem
%A Vonk, Vedran
%A Deyu, Getnet Kacha
%A Zierold, Robert
%A Blick, Robert
%A Wenskat, Marc
%A Hillert, Wolfgang
%A Stierle, Andreas
%T Influence of an Al<sub>2</sub>O<sub>3</sub> Capping Layer on the Thermal Reduction of the NativeNiobium Oxide: An In situ X-ray Reflectivity Study
%J Physical review materials
%V 9
%N 9
%@ 2475-9953
%C College Park, MD
%I APS
%M PUBDB-2025-02182
%P 094806
%D 2025
%X Superconducting radio-frequency cavities, critical components of modern particle accelerators andquantum computing hardware, rely fundamentally on the surface properties of niobium. However,native oxide formation and impurity uptake in the near-surface region can degrade superconductingperformance and increase RF losses during operation. In this study, we present a systematic in situX-ray reflectivity investigation of (110) niobium single crystal surfaces with and without an atomiclayer deposited Al<sub>2</sub>O<sub>3</sub> capping layer under ultra-high vacuum conditions up to 650 °C. Our resultsreveal a temperature-dependent reduction of the native niobium oxide layers in both capped anduncapped samples, with similarities in the overall behavior but clear differences in the reductionpathways. The Al<sub>2</sub>O<sub>3</sub> capping layer modifies the reduction process, prevents oxide regrowth uponair exposure, and protects the niobium surface against impurity uptake during thermal treatment.These findings demonstrate that Al<sub>2</sub>O<sub>3</sub> capping is an effective strategy to suppress native oxideformation during thermal cycling, offering clear benefits for the performance and operational lifetimeof superconducting radio-frequency cavities and related quantum computing technologies.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1103/48mp-wypj
%U https://bib-pubdb1.desy.de/record/632415