Detailed analysis of microcrystalline and nanocrystalline CeB6 phase formation, morphology and their electron emission performance

Abstract

Micro and Nano sized cerium hexaboride (CeB₆) were synthesized using high temperature processes viz. Self-propagation High temperature Synthesis (SHS) and arc plasma gas phase condensation route respectively. Economically viable oxide precursors of cerium and boron were used to obtain microcrystalline CeB₆ by SHS process. Further, these powders were used to obtained nanocrystalline thin sheets of cerium hexaboride by arc plasma gas phase condensation process. Novelty of these high temperature processes lies in the formation of single phase of CeB₆ without metastable states such as CeB₄ within a short interval of time. Optical emission spectroscopy was extensively used to observe evaporated species during arc plasma synthesis. Microcrystalline and nanocrystalline CeB₆ powders were characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. In view of electron emission applications, field emission measurements were carried out. Field emission measurements depicted maximum current density of 56 µA/cm² for microcrystalline CeB₆ and 96 µA/cm² and 222 µA/cm² respectively for nanocrystalline powders obtained using nitrogen and argon thermal plasma.