Negative ion formation from a low-work-function nanoporous inorganic electride surface

As one of candidate materials for a low work function plasma grid, a new inorganic material, C12A7 electride having the low work function and high electrical conductance, was studied experimentally. The photoelectric current from the material under irradiations with 325 nm He-Cd laser and 405 nm, 450 nm, 532 nm diode lasers was measured. The measured work function was less than 2.7 eV. Exposure to the C12A7 electride to an atomic hydrogen (H0) flux has produced electric current corresponding to negative hydrogen ion (H-) current from the surface. Similar characteristics were obtained for a low-work-function bi-alkali material covered molybdenum surface (∼2.3 eV). Nearly the same negative current signals were observed under the same exposure condition of atomic hydrogen flux.