Morphology tuning and electron emission properties of a carbonaceous LaB6 system obtained using a thermal plasma route

In the present study, we report the morphological tuning of carbonaceous nanocrystalline lanthanum hexaboride (LaB6) using an arc plasma route. It was possible to obtain different morphologies, namely: pebbles, rods and sheets, on a nano-scale by means of plasma assisted vapour phase growth and by varying the plasma current. At elevated plasma currents, as a consequence of graphite electrodes being used in the arc geometry, the synthesized product was obtained in the form of carbonaceous LaB6 having a high degree of crystallinity. Detailed morphological analysis using electron microscopy has revealed that nanorods and nanosheets of carbonaceous LaB6 can be grown by elevating the plasma currents. The field emission (FE) current was found to be enhanced from 200 A cm(-2) to 660 A cm(-2) for the hierarchical structure of nanosheets as compared to that of nanopebbles at a much reduced turn-on potential. A stable FE current is an important feature exhibited by all these LaB6 nanostructures.