Crucible‐Free Preparation of Transition‐Metal Borides: HfB2

This study gives an account of an innovative, crucible‐free technique for the synthesis of single‐phase borides at relatively moderate temperatures. A metal wire heated by an electrical current reacts with a chosen gaseous boron halide in a gas/solid reaction yielding a single‐phase, oxygen‐ and carbon‐free product, as evidenced by X‐ray powder diffraction and chemical analysis. This method is demonstrated using the example of hafnium reacting with boron tribromide. Preliminary thermodynamic considerations show that this kind of crucible‐free synthesis specifically enables the preparation of borides of transition metals and similar elements. Boride on the wire: A metal wire heated by an electrical current reacts with a chosen gaseous boron halide in a gas–solid reaction yielding a single‐phase, oxygen‐ and carbon‐free product. This innovative, crucible‐free technique for the synthesis of single‐phase borides at relatively moderate temperatures specifically enables preparation of borides of transition metals and similar elements.