Synthesis of lithium nitride for neutron production target of BNCT by lithium deposition and ion implantation

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

To achieve high performance of BNCT (Boron Neutron Capture Therapy) device, lithium nitride target for neutron production was synthesized by in-situ vacuum deposition and nitridation techniques. Following conclusions were derived; (1) Uniform lithium layer of a few hundreds nanometer was formed on Pd/Cu multilayer surface by vacuum deposition technique using metallic lithium as a source material. (2) Lithium nitrides were formed by nitridation by the implantation of low-energy nitrogen ions on the deposited lithium layer surface. The chemical states of the nitridated zone were close to the stoichiometric lithium nitride, LiN. (3) This nitridated zone formed on surface of four layered lithium target is stable for three months in air condition. The nitridation is effective to protect lithium target from degradation by unfavourable reactions.