Query

Steve et al.

I am interested to simulate TiAlN deformation. Literature suggest that the stoichiometry is strictly 1:1 between (Ti+Al) and N meaning thereby that Ti2Al2N is the material which is a real world material. Thermodynamically on the other hand, Ti4AlN3, Ti2AlN and Ti3AlN are stable in that order:

My first question is:

(1) where can I find the crystal structure of this complex material?

(2) Which potential function may be used. Literature is available to simulate TiN alone (MEAM 2NN) or TiAl (EAM alloy) but I could not find a reliable (single) potential to simulate TiAlN?

Advice will be sincerely appreciated.

SG.

Steve et al.

I am interested to simulate TiAlN deformation. Literature suggest that the
stoichiometry is strictly 1:1 between (Ti+Al) and N meaning thereby that
Ti2Al2N is the material which is a real world material. Thermodynamically
on the other hand, Ti4AlN3, Ti2AlN and Ti3AlN are stable in that order:

My first question is:

(1) where can I find the crystal structure of this complex material?

If the structure has been resolved experimentally an initial guess may be
available in crystallographic databases.

(2) Which potential function may be used. Literature is available to
simulate TiN alone (MEAM 2NN) or TiAl (EAM alloy) but I could not find a
reliable (single) potential to simulate TiAlN?

Are you sure you cannot conduct your study using QM simulations? If you
need classical potentials you need to make sure you exhaust all available
literature looking for answers. If the structure is not known
experimentally that may well be your first answer as to why you cannot find
works on the material. If the unit cell is not too big one can employ a
combination of evolutionary algorithms and QM simulations to find guesses
to the low enthalpy polymorphous.
Carlos

All three structures are readily available in crystallographic databases and in the literature:

For Ti3AlN you might look at Schuster, J.C. and Bauer, J., The ternary system titanium-aluminum-nitrogen, Journal of Solid State Chemistry 53, 260 - 265 (1984).

For Ti4AlN3, Rawn, C.J., Barsoum, M.W., El-Raghy, T., Procipio, A., Hoffmann, C.M. and Hubbard, C.R., Structure of Ti4 Al N3 - a layered Mn+1 A Xn nitride, Materials Research Bulletin 35, 1785 - 1796 (2000).

And for Ti2AlN, Bouhemadou, A., Khenata, R. and Chegaar, M., Structural and elastic properties of Zr2 Al X and Ti2 Al X (X = C and N) under pressure effect, The European Physical Journal B 56, 209 - 215 (2007) might be helpful.

As Carlos suggests, you might look into using DFT, particularly if you are interested in other stoichiometries — I am not sure what you mean by “deformation” — since forcefields will probably not handle such a complicated system. Ti4AlN3 is the largest system, with 16 atoms per unit cell, which is quite tractable by DFT using a code like VASP.

Paul