Debache, L., Medkour, Y., Djeghloul, F., Haddadi, K., Berri, S., Kharoubi, M., Bouarissa, N., Guechi, N., and Roumili, A.
In order to expand the scope of application of ternary nitrides and explore more thoroughly their potential as novel materials, ab initio calculations founded on density functional theory are executed to examine the mechanical, electronic, optical and transport properties of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 nitrides. These compounds are thermodynamically stable established on coherent energy and enthalpy of formation, with Ca 5 Si 2 N 6 having the best stability. The estimated values of elastic constants and their derived properties suggest that the items under examination are mechanically stable, ductile and elastically anisotropic. Electronic properties have been evaluated using the GGA and TB-mBJ exchange-correlation potentials. The band structure calculated via TB-mBJ reveals that these nitrides are semiconductors, where Ca 5 Si 2 N 6 has a direct energy gap of 3.55 eV and Sr 5 Ge 2 N 6 an indirect band-gap of 3.15 eV. By combining Debye temperature and band-gap values, it was concluded that the nitridosilicate compound can be used as phosphor material. According to the optical response, which was examined in terms of dielectric function, complex refractive index, absorption, reflectivity and energy damage function, the potential applications of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 have been discussed. Further, thermoelectric properties are computed utilizing the semi-classical Boltzmann transport notion. The obtained results show a large strength operator and depressed thermal conductivity driving to rising figure of merit values, particularly at 300 K (0.978–0.986), signifying that the studied ternary nitrides are favorable nominees for thermoelectric employments at both low and room temperatures. • The calculated elastic constants suggest that Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 nitrides are mechanically stable, ductile and elastically anisotropic. • The calculated band structure shows that Ca 5 Si 2 N 6 has a direct gap of 3.55 eV whereas Sr 5 Ge 2 N 6 is an indirect gap of 3.15 eV. • The combination of Debye temperature and band-gap values, showed that the nitridosilicate compound can be used as phosphor material. • The optical response has permitted the discussion on the potential applications of Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 materials. • The nitrides Ca 5 Si 2 N 6 and Sr 5 Ge 2 N 6 are found to be favorable nominees for thermoelectric employments at both low and room temperatures. [ABSTRACT FROM AUTHOR]