Composition change of the near-surface layer of Li2TiO3 after CO2 absorption observed with accelerator analyses

• Published in: Journal of nuclear materials 2013-11, Vol.442 (1-3), p.S442-S446
• Main Authors: Furuyama, Yuichi, Sasaki, Yuki, Gotoh, Yuji, Taniike, Akira, Kitamura, Akira
• Format: Article
• Language: English
• Subjects: Accelerators; Atomic beam spectroscopy; Backscattering; Carbon dioxide; Cross sections; Proton beams; Scattering; Spectroscopy
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2013.04.034

•The prepared Li2TiO3 samples were exposed to CO2 at room temperature.•NRBS analysis suggested composition change to Li2CO3 and TiO2 after the CO2 exposure.•Samples recovered the original composition of Li2TiO3 to emit CO2 by heating at 973K.•Physical expansion (10%) introduced by CO2 absorption remained after the recovery. Non-Rutherford backscattering spectroscopy (NRBS), which allows for a greatly enhanced cross section for scattering, was used to analyze the atomic composition of Li-containing blanket material, 2.6-MeV proton beams were used as the probe beam to profile the atomic composition in the near-surface region down to about 2μm. Li2TiO3 ceramics samples of various densities were exposed to CO2 gas at a pressure of 1atm at room temperature in a glove box. The absorption of CO2 was observed to result in the formation of Li2CO3 on these samples in the NRBS spectra. In low and medium density samples, the density ratio of the absorbed CO2 to Li2TiO3 reached 0.5 after 1800h and CO2 absorption showed a saturation tendency of about 1400h. Li2TiO3 structures without CO2 were recovered by heating samples to 973K, with a residual positive volume change of 10%. The structure appeared to have increased capacity for CO2 absorption with an expanded near-surface layer. This characteristic could present a problem in the process of tritium recovery from the blanket materials.