First-principles insights on mechanical and electronic properties of TiX (X=C,N) in β-Si3N4 based ceramics

The mechanical and electronic properties of ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics are investigated using density functional theory implemented with GGA/PBE functional. The pristine ?-Si3N4 exhibits fracture for a strain of 10%. However, TiC-Si3N4 and TiN-Si3N4 ceramics exhibits fracture for a strain of 20%. The Young?s modulus, shear modulus and bulk modulus of the pristine ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics are reported. TiN-Si3N4 ceramic is found to be the least compressible and hard. The band gap is found to decrease for TiC-Si3N4 and TiN-Si3N4 ceramics comparedwith the pristine ?-Si3N4. The density of states spectrumshows more peak maxima for TiC-Si3N4 and TiN-Si3N4 ceramics rather than ?-Si3N4. The finding of the present work gives a clear insight on the mechanical and electronic properties of ?-Si3N4, TiC-Si3N4 and TiN-Si3N4 ceramics at the atomistic level.