Field emission of electron anions clathrated in subnanometer-sized cages in [Ca24Al28O64]4+(4e-)

[Ca24Al28O64](4+) (4e(-)) is a new inorganic electride, which is air-stable even at similar to 300 degreesC. Its electron field-emission properties originate from electron anions encaged in subnanometer-sized cages embedded in its crystal structure, and the emission current is controlled by Fowler-Nordheim field emission at high electric fields (see Figure). Field-emission display devices demonstrate bright light emission clearly visible under ambient light (inset).