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　LaB　6　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.　©　2010　IEEE.