Field emission characteristics of polycrystalline LaB6 single tip and surface electric field distribution

Lanthanum hexaboride (LaB6) as an excellent thermionic electron emitter was characterized by high brightness, thermal stability, low volatility and high mechanical strength ^[1]. The advantages are originated from its low work function (2.4 eV∼2.6 eV), high melting point (2715°C) and covalent bond of B-B atom in crystal structure. Recently, many researchers focused their attention on the excellent field emission properties of LaB6 one-dimensional nanoelectronics as well as nanomachine applications ^[2]. Late et al. ^[3] have reported the LaB6 tips and foils grown on tungsten and rhenium substrate by Pulsed laser deposition (PLD) at temperature 700°C with average grain size ∼ 125nm. However, there are some disadvantages of above-mentioned methods. The BCl3 as the boron source is easy to absorb water and convert into boric acid, which resist the reaction. The stoichiometry of the products was hard to control by gaseous starting materials. For thin films, there have some intrinsic disadvantages, including poor adhesion to the substrate and oxide contained in the emitter. Compared to the nanowires and nanofilms, the bulk materials can provide large size, low cost, simple preparation. Therefore, there are great research prospects for polycrystalline LaB6 Field emission properties.