DFT study of the crystal structure, elastic and electronic properties of the phases: Ti2InC(1-x)Nx superconductor.

A systematic study was conducted to investigate the effect of substituting C by N on the crystal structure and elastic electronic properties in the Ti 2 InC (1-x) N x phases using the DFT framework implemented in the CASTEP code. Initially, the crystalline structure was stabilized by geometric optimization of the Ti 2 InC (1-x) N x phases. The structural properties showed that the lattice parameters a and c and, consequently, the volume decreased because of the difference between the ionic radius of C and N. According to Born's structural stability criterion, the phases with a hexagonal structure are stable for all the ranges of N content studied. Analysis of mechanical moduli shows an increase between 0.00 < x < 0.25 and a decrease for x > 0.50 in Young's modulus. At the same time, the Pugh and Poisson ratios show the phases are brittle between 0.00 < x < 0.75, ductile for x = 1.00, and all metallic, respectively. Electronic band structure calculations confirm this metallic behavior, supported by the DOS analysis. Finally, as expected, the PDOS shows an increase in the electronic states of the 2 p -C (N) orbitals because of the substitution of C for N. Consequently, the density of states at the Fermi level N(E F = 0) increases as the N content rises. Finally, using the Frolich model, we observe an increase in T c as the N content increases; as a result, the electron-phonon coupling constant values increase from 0.51 to 0.62; these values imply the phases are moderately coupled superconductors. • A systematic study was conducted to investigate the effect of substituting C by N on the crystal structure and elastic electronic properties in the Ti 2 InC (1-x) N x phases using the DFT. • Using the Frolich model, we observe an increase in Tc as the N content increases; as a result, the electron-phonon coupling constant values increase from 0.51 to 0.62; these values imply the phases are moderately coupled superconductors. • Analysis of the electronic band structure and DOS shows that all phases exhibit metallic behavior. • In accordance with the results obtained in this work, the increase of states in DOS (at N(E F)) is due to the 3 d -Ti orbital (due to this contribution, the metallic behavior is obtained), which may be responsible for increasing the superconducting transition temperature. [ABSTRACT FROM AUTHOR]