Abstract
NbB2 (AlB2-type, hexagonal) powder was synthesized by ball milling of Nb-B (1 : 2) mixture using planetary ball mill with balls of 5 mm, 9 mm or 16 mm diameter, and the effect of the ball sizes on the preparation of NbB2 was examined. When milled with balls of 5 mm, 9 mm and 16 mm diameters, the starting time of the NbB2 formation was 20 hrs, 10 hrs and 5 hrs, respectively, and the single phase of NbB2 was obtained in 50 hrs, 30 hrs and 20 hrs, respectively. The time required for the formation of the NbB2 single phase decreased with the increase in the ball size. The lattice parameters of the NbB2 obtained were a = 0.3112 nm, c = 0.3276 nm. The specific surface area of the NbB2 powder decreased with increase in the ball size. The average particle size of the NbB2 powder obtained by milling with the 5 mm diameter balls for 50 hrs was approximately 370 nm. The contaminant in NbB2 powder from the vial and balls decreased with decrease in the ball size.
