Structural, Elastic, Electronic and Optical Properties of a New Layered-Ternary Ta4SiC3 Compound

We propose a new layered-ternary Ta4SiC3 with two different stacking sequences ({\alpha}- and {\beta}-phases) of the metal atoms along c axis and study their structural stability. The mechanical, electronic and optical properties are then calculated and compared with those of other compounds M4AX3 (M = V, Nb, Ta; A = Al, Si and X = C). The predicted compound in the {\alpha}-phase is found to possess higher hardness than any of these compounds. The independent elastic constants of the two phases are also evaluated and the results discussed. The electronic band structures for {\alpha}- and {\beta}-Ta4SiC3 show metallic conductivity. Ta 5d electrons are mainly contributing to the total density of states (DOS). We see that the hybridization peak of Ta 5d and C 2p lies lower in energy and the Ta 5d-C 2p bond is stronger than Ta 5d-Si 3p bond. Further an analysis of the different optical properties shows the compound to possess improved behavior compared to similar types of compounds.