Sun, Z. Baraissov, Z. Liepe, M. Muller, D.A. Oseroff, T.E. Thompson, M.O. JACoW Publishing Geneva, Switzerland 2673-5504 978-3-95450-234-9 10.18429/JACoW-SRF2023-TUPTB006 English 401-404 cavity SRF plasma controls niobium Contribution to a conference proceedings 2023 2023-09 https://doi.org/10.18429/JACoW-SRF2023-TUPTB006 https://jacow.org/srf2023/papers/tuptb006.pdf Materials scientists seek to contribute to the development of next-generation superconducting radio-frequency (SRF) accelerating cavities. Here, we summarize our achievements and learnings in designing advanced SRF materials and surfaces, including Nb₃Sn [1¿3], ZrNb(CO) [4, 5], and Au/Nb surface design [6,7]. Our efforts involve electrochemical synthesis, phase transformation, and surface chemistry, which are closely coupled with superconducting properties, SRF performance, and engineering considerations. We develop electrochemical processes for Sn, Zr, and Au on the Nb surface, an essential step in our investigation for producing high-quality Nb₃Sn, ZrNb(CO), and Au/Nb structures. Additionally, we design a custom chemical vapor deposition system to offer additional growth options. Notably, we find the second-phase NbC formation in ZrNb(CO) and in ultra-high-vacuum baked or nitrogen-processed Nb. We also identify low-dielectric-loss ZrO2 on Nb and NbZr(CO) surfaces. These advancements provide materials science approaches dealing with fundamental and technical challenges to build high-performance, multi-scale, robust SRF cavities for particle accelerators and quantum applications.