The controlled synthesis of lanthanum hexaboride nanostructures with efficient field emission properties was described. Synthesis was mediated by a nanostructured lanthanum hydroxide precursor, which was controlled by varying the capping agent and pH using a hydrothermal route. The effect of charge upon the capping agent (surfactant) strongly affected the shape and size of the precursor (neutral surfactants led to the formation of nanorods while a cationic surfactant resulted in the formation of particles). This precursor-mediated route led to lanthanum hexaboride nanostructures at temperatures that were ∼500C lower than that for the conventional solid state route and allowed for variation of the morphology of nanostructured films. Vertically aligned nanorods (30nm x 200-400nm), nanoparticles (25nm) and sub-micron particles (0.2-0.25 microns) could be precisely obtained. Field emission studies of the vertically aligned nanorods indicated a very high field enhancement factor (4191).

Manipulating the Anisotropy and Field Emission of Lanthanum Hexaboride Nanorods. Menaka, P.R., Ghosh, S., Ganguli, A.K.: RSC Advances, 2012, 2[20], 7875-85