SYNTHESIS OF THE B1-TYPE TANTALUM NITRIDE BY SHOCK COMPRESSION

B1-type tantalum nitride (polycrystalline bulk state) was synthesized by shock compression. Shock-compression recovery experiments of the po rous sample of tantalum nitride with a hexagonal structure (CoSn-type) were performed in the impact-velocity range up to 1.5 km s-1. The ins trumental chemical analysis, X-ray and electron diffraction experiment s were carried out on the recovered tantalum nitride sample and the co mbustion-synthesized B1-type sample for comparison. The recovery rate of the B1-type phase increased with increasing porosity, impact veloci ty and impactor thickness; among these above all the effect of porosit y was most remarkable. Almost 100% recovery rate was achieved for the powder of 70% porosity impacted by a 2 mm thick tungsten plate with ve locities above 1.4 km s-1. It was confirmed by chemical analysis that the nitrogen content did not change by shock compression. The chemical formulae of the shock-synthesized and combustioned-synthesized B1-typ e phases were estimated to be TaN0.96-0.99 and TaN1.13-1.16, 1.27-1.30 , respectively. The lattice parameter of the shock-synthesized B1-type (Fm3m) phase was a0 = 0.433 63- + (1) nm. The results of X-ray and el ectron diffraction experiments also supported that the shock-synthesiz ed B1-type tantalum nitride has a good stoichiometry compared with the combustion-synthesized ones.