Surficial chemical states of LiN synthesized on lithium target for boron neutron capture therapy

Ishiyama, Shintaro; Baba, Yuji  ; Fujii, Ryo*; Nakamura, Masaru*; Imahori, Yoshio*

To remove high level of contaminants by O and C from LiN surface for BNCT target, high temperature thermal desorption was conducted up to 1123 K in ultra high vacuum and the following results were derived; (1) During thermal desorption up to 1023 K, typical three peaks of vacuum pressure disturbance due to vaporization of contaminants were observed in vacuum pressure-temperature curve. (2) Over-layered contaminants with high melting temperature below 1023 K on LiN surface is completely removed by high temperature thermal desorption up to 1123 K in ultra high vacuum. (3) From these desorption results, it is suggested that these contaminants corresponding to these vaporization peaks are HO and Li compounds with high melting temperature below 1023 K, of which LiOH and LiCO were synthesized by decomposition process of LiN with residual HO and CO in low temperature.