Abstract
We have investigated various physical properties including phonon dispersion, thermodynamic parameters, optical constants, Fermi surface, Mulliken bond population, theoretical Vickers hardness, and damage tolerance of anti-perovskite A3BX phases for the first time by employing density functional theory methodology based on the first principles method. Initially, we assessed nine A3BX phases in total and found that only three phases (Ti3TlN, Ni3SnN, and Co3AlC) are mechanically and dynamically stable based on the analysis of computed elastic constants and phonon dispersion along with phonon density of states. We revisited the structural, elastic, and electronic properties of the compounds to judge the reliability of our calculations. The absence of bandgap at the Fermi level characterizes the phases under consideration as metallic in nature. The values of Pugh ratio, Poisson’s ratio, and Cauchy factor have predicted the ductile nature associated with strong metallic bonding in these compounds. A high temperature feasibility study of the phases has also been performed using the thermodynamic properties, such as the free energy, enthalpy, entropy, heat capacity, and Debye temperature. The Vickers hardness of the compounds is estimated to be ∼4 GPa, which is comparable to many well-known MAX phases, indicating their reasonable hardness and easily machinable nature. The static refractive index n(0) has been found around ∼8.0 for the phases under study that appeals as a potential candidate to design optoelectronics appliances. The reflectivity is found above 44% for the Ti3TlN compound in the energy range of 0 eV–14.8 eV, demonstrating that this material holds significant promise as a coating agent to avoid solar heating.
Highlights
One of the biggest challenges in designing the structural materials is that it should have high stiffness associated with damage tolerant behavior
We have investigated various physical properties including phonon dispersion, thermodynamic parameters, optical constants, Fermi surface, Mulliken bond population, theoretical Vickers hardness, and damage tolerance of anti-perovskite A3BX phases for the first time by employing density functional theory methodology based on the first principles method
First principles calculations based on the density functional theory (DFT) have been employed to study thermodynamic parameters, optical properties, Fermi surface topology, Mulliken bond overlap population, and Vickers hardness of the recently reported damage tolerant Ti3TlN (TTN), Ni3SnN (NSN), and high stiffness Co3AlC (CAC) anti-perovskite materials for the first time
Summary
One of the biggest challenges in designing the structural materials is that it should have high stiffness (i.e., should be reasonably hard materials) associated with damage tolerant behavior. Ductility assessment is one of the ways to define a material as damage tolerant. Some binary carbides and nitrides are known to have high elastic moduli and brittleness.[4,5,6,7,8] Their damage tolerant behavior can be improved by incorporating a weak layer to form a laminated structure with alternative strong and weak stacking layers
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