Synthesis and characterization of the ternary metal diboride solid‐solution nanopowders

Abstract The synthesis of the multi‐component transition‐metal diboride (MeB 2 ) solid‐solution powders has been recently attracting considerable attentions. However, the synthesis of the ternary or more component MeB 2 solid‐solution powders has rarely been reported until now. To fabricate the ternary MeB 2 solid‐solution powders, herein we utilized two kinds of the ternary MeB 2 solid solutions as prototypes, namely (Hf 1/3 Zr 1/3 Ti 1/3 )B 2 (HZTB) and (Ta 1/3 Nb 1/3 Ti 1/3 )B 2 (TNTB). The formation possibility of HZTB and TNTB was first analyzed by the first‐principles calculations and then we attempted of fabricated them by a simple molten salt synthesis technique. The first‐principles calculations results showed that the mixing Gibbs free energy at room temperature and lattice size difference at 0 K of HZTB and TNTB were (1.666 kJ/mol and 3.146%) and (−3.030 kJ/mol and 1.254%), respectively. This suggested that TNTB solid solution was more prone to being fabricated than HZTB solid solution. The experimental results showed the high purity TNTB solid‐solution nanopowders were successfully synthesized by the molten salt synthesis technique at 1373 K with 30% excessive B as precursors while the HZTB solid solution was not able to be synthesized by the molten salt synthesis technique. The as‐synthesized TNTB solid‐solution nanopowders exhibited the distinguished nanorod morphology with the diameters of 20‐40 nm and lengths of 100‐200 nm. Meanwhile, they possessed the good single‐crystal hexagonal structure and high compositional uniformity from nanoscale to microscale. In addition, their formation mechanism associated to the possible chemical reactions was well interpreted by the thermodynamics analysis.