|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Environmentally Assisted Cracking: Theory and Practice
||Role of Nitrogen on Hydride Nucleation and Stability in Pure Niobium by First-principles Calculations
||Pulkit Garg, Ilaksh Adlakha, Kiran N. Solanki
|On-Site Speaker (Planned)
The formation and growth of niobium hydride degrades the superconducting radio frequency (SRF) properties of niobium cavities and reduces the quality factor. Recently, the addition of nitrogen has been shown to improve the quality factor of SRF niobium but the underlying mechanisms are unclear. Thus, in this work, the role of nitrogen solute addition in niobium on hydride precipitation and stability is probed through first principles calculations. In presence of nitrogen the energetic preference for hydrogen to occupy interstitial sites in the vicinity is reduced. Furthermore, both interstitial octahedral and tetrahedral sites become equally favorable for hydrogen to occupy far away from nitrogen.Also, the thermodynamic stability of beta niobium hydride precipitates decreases in presence of nitrogen in niobium.The quantum insights, calculated using valence charge transfer and density of states, reveal a strong tendency for nitrogen to accumulate charge, thereby decreasing the bond strength of neighboring niobium and hydrogen atoms.
||Planned: Supplemental Proceedings volume