Exploring the electronic, elastic, optical, thermal, and structural characteristics of silicon nitride (Si3N4) ceramic by employing the FP-LAPW method

This paper presents a comprehensive firstــprinciples investigation into the structural, electronic, elastic, optical, thermal, and mechanical characteristics of the polymorphic ceramic β−Si3N4. The analysis employs the highly reliable fullــpotential linearized augmented plane wave (FP-LAPW) approach, executed within the robust context of density functional theory (DFT) using the WIEN2k package. Structural optimization utilizes the PerdewــBurkeــErnzerhof (PBE) version of the generalized gradient approximation (GGA). Notably, the electronic band gap is accurately determined using the superior modified Becke–Johnson (mBJ) functional, which offers enhanced predictive power over conventional approximations. The six independent elastic constants are derived directly from the stress–strain responses under minute deformations, which subsequently informs the prediction of the overall mechanical behavior of β−Si3N4. Band structure analysis confirms the intrinsic semiconducting nature of the compound. Optical behavior is explored by calculating the complex dielectric function ϵ(ω) and its related parameters, including the refractive index, extinction coefficient k(ω), absorption coefficient α(ω), reflectivity R(ω), and the electron energy-loss function L(ω). Furthermore, thermal features are meticulously examined through the quasi-harmonic Debye model, enabling the determination of critical thermodynamic properties such as the equilibrium volume, bulk modulus, and specific heat capacity as a function of temperature and pressure. The computed results demonstrate excellent consistency with established theoretical and experimental data, thereby validating the methodological rigor. These findings establish the critical reliability of β−Si3N4and underscore its immense potential for advanced technological and scientific applications, offering a valuable benchmark for future research in materials science.