Low temperature synthesis of lithium-nitride compound was conducted on the lithium target for BNCT by N2/H2O mixing gas squirt in the ultra high vacuum chamber, and the following results were derived; (1) Lithium-nitride compound was synthesized on the lithium target under 101.3 Pa N2 gas squirt at room temperature and in the ultra high vacuum chamber under the pressure of 1×10−8 Pa. (2)Remarkable contamination by O and C was observed on the lithium-nitride compound synthesized under the squirt pressure of 13.3~80 Pa/1.33~4.7 Pa N2/H2O mixing gas. (3) No contamination and synthesis of Li-N compound was observed under the squirt pressure of 0.013~0.027 Pa/0~0.005 Pa N2/H2O mixing gas. (4) Contamination by O and C was enhanced with excessive addition of H2O at the pressure of over 1.33 Pa.
