Analysis of Interstitial Elements in Niobium with Secondary Ion Mass Spectrometry (SIMS)

Journal Article · Thu Mar 31 00:00:00 EDT 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3580641· OSTI ID:21516670

Maheshwari, P; Griffis, D P ^[1]; Stevie, F A ^[1]; Myeneni, G; Ciovati, G ^[2]; Rigsbee, J M ^[3]

---

1. Analytical Instrumentation Facility, North Carolina State University, Raleigh, NC 27607 (United States)
2. Jefferson Laboratory, Newport News, VA 23606 (United States)
3. Materials Science and Engineering, North Carolina State University, Raleigh, NC 27607 (United States)

Superconducting Radio Frequency (SRF) cavities provide enhanced efficiency and reduced energy utilization in present day particle accelerators. Niobium (Nb) is the material of choice for these cavities due to its high critical temperature and critical magnetic field. In order to understand why certain treatments, especially a low temperature bake, improve performance, it is important to study Nb surface characteristics and identify elemental contamination that can affect the performance of the cavity. H, C, O, and N are of interest because they are interstitial impurities in Nb. In earlier work, SIMS analysis using a CAMECA IMS-6F with Cs{sup +} primary beam showed that C and N were probably not significant factors impacting performance but there was a very high level of H in the Nb. Ion implants of C, N, O, and D into Nb provided quantification of C, N, O and indicated that D is very mobile in the Nb. Further analyses showed that heat treated Nb has lower levels of surface H than non heat treated Nb and subsequent removal of surface oxide by etching causes intake of H in a heat treated Nb sample. This result helps confirm the role of surface oxide as a hydrogen barrier. To further understand the oxide, Nb samples were anodized to obtain a thicker surface oxide and H and D were implanted into this oxide to check for the appearance of implant peaks. SIMS depth profile analyses were carried out and confirmed the presence of the implant shape for these elements in the oxide. Relative Sensitivity Factor (RSFs) could then be calculated for quantification of H in the oxide. Since the Nb matrix signal showed little change from the oxide to the substrate, the same RSF was used to estimate the H concentration in the Nb at 2x10{sup 22} atoms/cm{sup 3}(approximately 40% mole fraction H).

• OSTI ID: 21516670
• Journal Information: AIP Conference Proceedings, Vol. 1352, Issue 1; Conference: 1. international symposium on the superconducting science and technology of ingot niobium, Newport News, VA (United States), 22-24 Sep 2010; Other Information: DOI: 10.1063/1.3580641; (c) 2011 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAVITIES
CESIUM IONS
CONTAMINATION
CRITICAL TEMPERATURE
ENERGY CONSUMPTION
ETCHING
HEAT TREATMENTS
INTERSTITIALS
ION MICROPROBE ANALYSIS
MAGNETIC FIELDS
MASS SPECTRA
MASS SPECTROSCOPY
NIOBIUM
NIOBIUM IONS
RADIOWAVE RADIATION
SENSITIVITY
SUBSTRATES
SURFACES
CHARGED PARTICLES
CHEMICAL ANALYSIS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
ELEMENTS
IONS
METALS
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
PHYSICAL PROPERTIES
POINT DEFECTS
RADIATIONS
REFRACTORY METALS
SPECTRA
SPECTROSCOPY
SURFACE FINISHING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE