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Title Oxygen-Free Titanium Thin Film as a New Nonevaporable Getter with an Activation Temperature as Low as 185 °C
  • M. Ono, I. Yoshikawa, K. Yoshioka
    University of Tokyo, Kashiwa, Japan
  • T. Kikuchi, K. Masepresenter
    KEK, Tsukuba, Japan
  • K. Masepresenter
    Sokendai, The Graduate University for Advanced Studies, Tsukuba, Japan
  • Y. Masuda, Y. Nakayama
    Tokyo University of Science, Noda, Japan
  • S. Ohno
    Yokohama National University, Yokohama, Japan
  • K. Ozawa
    TIT, Tokyo, Japan
  • Y. Sato
    Yokohama National University, Graduate School of Engineering Science, Yokohama, Japan
Abstract Although nonevaporable getter (NEG) pumps are widely used in synchrotron radiation facilities, pure metal Titanium (Ti) has not been used as a NEG because the activation temperature of a Ti thin film deposited by DC magnetron sputtering was reported to be 350-400 °C*. Recently Miyazawa et al. found that high-purity Ti deposited under ultra-high vacuum (UHV) followed by N₂ introduction works as a NEG with an activation temperature of 185 °C**,***. Since the concentration of impurities such as O, C, and N in the Ti thin film prepared by this method is 0.05% or less, we named this as oxygen-free Ti. In this study, we evaluated the pumping properties of oxygen-free Ti thin films after high-purity N₂ introduction by total and partial pressure measurements. A vacuum vessel with oxygen-free Ti deposited on the inner walls was found to pump H₂, H₂O, O₂, CO and CO₂ even after 30 cycles of high purity N₂ introduction, air exposure, pumping, and baking at 185 °C. Furthermore, we analyzed the oxygen-free Ti thin films after high-purity N₂ or air introduction by synchrotron radiation X-ray photoelectron spectroscopy. The results show that more TiN was formed when high-purity N₂ was introduced after oxygen-free Ti deposition. High purity of the Ti thin film and TiN formation on the surface seem to be responsible for the reduced activation temperature as low as 185 °C.
Footnotes & References *C. Benvenuti et al., J. Vac. Sci. Technol. A 16, 148 (1998).
**T. Miyazawa et al., Vac. Surf. Sci. 61, 227 (2018).
***KEK, patent pending, WO2018097325 (Nov. 28, 2017).
Funding This work was partly supported by JSPS KAKENHI (17K05067, 19K05280) and TIA-Kakehashi (TK19-035, TK20-026). The XPS measurements were performed under the Photon Factory proposal (2018S2-005).
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Conference MEDSI2020
Series Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation (11th)
Location Chicago, IL, USA
Date 24-29 July 2021
Publisher JACoW Publishing, Geneva, Switzerland
Editorial Board Yifei Jaski (ANL, Lemont, IL, USA); Patric Den Hartog (ANL, Lemont, IL, USA); Kelly Jaje (ANL, Lemont, IL, USA); Volker R.W. Schaa (GSI, Darmstadt, Germany)
Online ISBN 978-3-95450-229-5
Online ISSN 2673-5520
Received 30 July 2021
Accepted 14 October 2021
Issue Date 01 November 2021
DOI doi:10.18429/JACoW-MEDSI2020-TUPA01
Pages 119-122
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