M. Roknuzzaman, A. K. M. A. Islam
The structural parameters, elastic, electronic, thermodynamic and optical properties of superconducting MAX phases Ti2InX (X = C, N) are investigated by the plane wave psedudopotential method based on density functional theory (DFT). The results obtained from the least studied nitride phase are discussed in comparison with those of carbide phase having Tc-value half as that of the former. The analysis of the band structure, density of states shows that these compounds are electrical conductors, with contribution predominantly from the Ti 3d states. The temperature and pressure dependence of bulk modulus, Debye temperature, specific heats, thermal expansion coefficient of the nanolaminates are all obtained for the first time through the quasi-harmonic Debye model with phononic effects for T = 0-1500K and P = 0-50GPa. The estimated values of electron-phonon coupling constants imply that Ti2InC and Ti2InN are moderately coupled superconductors. The thermal expansion coefficients for both the phases are calculated, and the calculation is in fair agreement with the only available measured value for Ti2InC. Further the first time analysis of all optical functions reveals that the reflectivity is high in the IR-visible-UV region up to ~ 10 eV and 13 eV for Ti2InC and Ti2InN, respectively showing promise as good coating materials. Keywords: Ti2InX superconductors; First-principles; Mechanical properties; Band structure; Quasi-harmonic Debye model; Thermodynamic properties; Optical properties
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http://arxiv.org/abs/1206.4514
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