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

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 2 mu m. Li2TiO3 ceramics samples of various densities were exposed to CO2 gas at a pressure of 1 atm 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 1800 h and CO2 absorption showed a saturation tendency of about 1400 h. Li2TiO3 structures without CO2 were recovered by heating samples to 973 K, 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. (C) 2013 Elsevier B.V. All rights reserved.