Synthesis of LaB6 from BN and lanthanum-citrate-hydrate

Lanthanum hexaboride was synthesized by reacting a powdered mixture of hexagonal boron nitride and lanthanum-citrate-hydrate carbonized substance which had been prepared by heating lanthanum-citrate-hydrate at 1000° C in a nitrogen atmosphere. The optimum conditions for the synthesis were a ratio of boron to lanthanum in the starting mixture between 5.0 and 6.0 with heating in the temperature range 1480 and 1600° C in an evacuated atmosphere.