Tantalum arsenide is a compound of tantalum and arsenic with the formula TaAs. It is notable as being the first topological Weyl semimetal that was identified and characterized by ARPES. It exhibits an analogue of quantum vortices in momentum space.
Tantalum arsenide crystallizes in a body-centered tetragonal unit cell with lattice parameters a = 3.44 ÃÂ and c = 11.65 ÃÂ . It belongs to the space group I4<sub>1</sub>md.
TaAs has been prepared by decomposing TaAs<sub>2</sub> at 900 ðC. A more recent preparation yielded large, single crystals of TaAs by chemical vapor transport with elemental precursors and iodine as the transport agent: