Mechanical Properties of Metal Nitrides for Radiation Resistant Coating Applications: A DFT Study

Metal nitrides compounds like aluminum nitride (AlN), titanium nitride (TiN), tantalum nitride (TaN), hafnium nitride (HfN) and zirconium nitride (ZrN) are of great interesting because of their chemical and physical properties such as: high melting point, resistivity, thermal conductivity and extremely high hardness. They are the materials of choice for various applications like protective coating for tools, diffusion barriers or metal gate contact in microelectronics, and lately their potential applications as radiation-resistive shields. In order to assess their use for radiation tolerance we have studied the structural, mechanical and electronic properties. We have evaluated the anisotropic elastic constants and their pressure dependence for three different crystalline phases: B1-NaCl, B2-CsCl, and B3-ZnS crystal structures. In addition to these cubic polymorphs, we also have studied potential hexagonal structures of some of the same metal nitrides. All computations are carried out using first principles Density Functional Theory (DFT) approach.