Thermal emission of alkaline ions from solid electrolyte: evidence of nonstoichiometric reaction

The emission of alkaline ions from zeolite 4A has been studied for elucidating the mechanism of thermionic emission from solid electrolytes. The zeolite heated on an inert ceramic holder with infrared light does not emit neutral and charged species except for alkaline metal ions R+, which indicates that the thermionic emission is a nonstoichiometric chemical reaction, as RAlO2SiO2→δR++δe−+R1−δAlO2SiO2. The parallelism between the intensity of the thermionic emission and the ionic conductivity of the zeolite suggests that the ionic conduction of alkaline ions is necessary for reducing the energy of the thermionic emission.