An X-Ray Study of the Tantalum-Nitrogen System.

In situ observation of the reaction of tantalum with nitrogen in a laser heated diamond anvil cell

“…Hence, the activation energy for this reaction seems to be small at elevated pressure. TaN x has been reported in a range of non-stoichiometric compositions up to x = 0.15 with a cell parameter of 3.369 Å for x ≈ 0.05 [41]. The cell parameter refined at ambient conditions from the sample of experiment 3 (Table 2), which was recovered after CO 2 -laser heating at 9(1) GPa, is slightly larger with a = 3.39(1) Å, which is supposed to be related to a higher nitrogen content (0.05 < x < 0.15) from nitridation at high pressure and temperature.…”

“…This can be attributed to the incorporation of small amounts of nitrogen into tantalum. Already Schönberg [41] has reported the incorporation of nitrogen in tantalum forming non-stoichiometric TaN 0.05 with an expanded lattice parameter of 3.369 Å compared to that of pure tantalum with 3.311 Å [41]. This was confirmed by the nitrogen-tantalum phase diagram showing the formation of TaN x with x up to 0.15 at high temperatures (<3200 K) and of Ta 2 N and TaN on successive nitridation ( [42,43] cited in [1]).…”

Ordered CoSn-type ternary phases in Co3Sn3−xGex

“…The Co atoms are surrounded by an octahedron of Sn atoms, but because the in-plane CoACo distances are the same as the CoASn bond distances, the Co atoms are actually 10 coordinate. The B35 structure has only been observed for intermetallic compounds with 12 or 13 valence electrons per transition metal (excluding ionic anti-CoSn type compounds such as Ti 2 O 1Àx and e-TaN [1,2]). That is, it includes a late transition metal element (Fe, Co, Ni, Rh, or Pt), and an early main group metal from either group 13 or 14 (Ga, In, Tl, Ge, Sn, or Pb).…”

Electronic properties of cubic TaCxN1−x: A comparative study using self-consistent cluster and ab initio band-structure calculations and X-ray spectroscopy

“…Tantalum monocarbide, TaC x , being the highest melting point material known so far (3983 • C [2]), crystallizes in the composition range 0.7 ≤ x ≤ 1.0 with the cubic B1 (NaCl-type) structure, while tantalum mononitride crystallizes in the hexagonal B35 (CoSn-type) structure at the stoichiometric composition TaN [9]. Probably, the mentioned difference in the crystal structures of tantalum monocarbide and mononitride is the main reason of the fact that conventional powder metallurgy methods do not allow to synthesize a continuous single-phase TaC x N 1 − x solid solution using as precursors the hexagonal close-packed (hcp) -TaN (structure of CoSn-type) and face-centred cubic (fcc) TaC (structure of NaCl-type) compounds: a phase transition from the fcc to hcp structure occurs in the TaC x N 1 − x system at x = 0.4 [10].…”