Catalytic effect of potassium carbonate on carbothermic production of hexagonal boron nitride

Abstract

Abstract Effect of potassium carbonate addition on the carbothermic formation of hexagonal boron nitride (hBN) was investigated by keeping the K 2 CO 3 added B 2 O 3 +C mixtures in nitrogen atmosphere at 1400 °C for 40–160 min. K 2 CO 3 amount was varied in the range of 10–60 wt% of the B 2 O 3 +C mixture. Products were subjected to XRD and quantitative analyses, SEM and TEM observations, and particle size measurement. Amount of hBN increased considerably with K 2 CO 3 addition; also particle size and crystallinity improved. Catalytic role of K 2 CO 3 was suggested as forming a potassium borate melt in which hBN particles form, in addition to carbothermic formation reaction. Effect of K 2 CO 3 on increasing the hBN amount decreased when it was used over 40%. This was attributed to the rapid evaporation of the formed potassium borate liquid.