LaBe6.0-6.14 crystals were prepared by using the floating zone method. The thermionic emission properties were examined at 1100 to 1500C. Increasing the boron content hardly influenced the emission characteristics, but decreased the evaporation rate which governed the lifetime of the cathode.

Crystal Growth and Thermionic Emission Properties of Boron-Rich LaB6 and CeB6. Otani, S., Souda, R., Ishizawa, Y.: Journal of the Ceramic Society of Japan, 1996, 104[11], 1088-90