Single-Crystalline CeB_6 Nanowires

摘要

Single-crystalline rare-earth hexaborides,especially lanthanum hexaboride (LaB_6) and cerium hexaboride (CeB_6),are thermionic cathode materials widely used in a broad range of electron beam applications where a high brightness electron source with long service life is required.The advantage of using rare-earth hexaboride originated from its crystal structure,which is composed of rare-earth metal atoms embedded inside a stable boron octahedron network.This arrangement allows a unique combination of all the desired properties for an excellent cathode material,such as low work function,low volatility,low electrical resistivity,high mechanical strength,and high chemical resistance,while these properties seldom coexist in any other materials.Compared to LaB_6,CeB_6 is believed to have even lower work function (approx2.5 eV) and lower volatility,which mean lower operation temperature and longer service life when used as a thermionic electron emitter.