Hardness and electronic properties of Si-C-N structures

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Exploration of novel materials with tailored electronic and mechanical properties is crucial for technological advancement.
• Silicon carbon nitride (Si-C-N) compounds offer a promising avenue due to the diverse bonding possibilities between Si, C, and N.
• Understanding the fundamental properties of new Si-C-N structures is essential for predicting their potential applications.

Purpose of the Study:

• To computationally design and characterize novel hexagonal Si-C-N structures.
• To investigate the stability, electronic conductivity, and mechanical hardness of these new materials.
• To identify potential applications based on their predicted properties.

Main Methods:

• Construction of three novel hexagonal Si-C-N structures (SiC3N3, SiC7N6, SiC13N14) based on the α-Si3N4 crystal structure.
• Analysis of elastic constants and phonon dispersion spectra for stability assessment.
• Calculation of formation energies, band structures, partial densities of states, and electron orbital analyses.
• Estimation of Vickers hardness using two hardness models and indentation shear stress calculations.

Main Results:

• SiC3N3 and SiC7N6 structures exhibit hole conductivity, with 3D and 1D conductivity respectively.
• SiC13N14 is identified as a semiconductor with a wide bandgap of 4.39 eV.
• Estimated Vickers hardness values indicate SiC3N3 and SiC7N6 as conductive hard materials, and SiC13N14 as a quasi-superhard material.

Conclusions:

• The newly designed Si-C-N structures demonstrate a range of promising properties.
• SiC3N3 and SiC7N6 are suitable for applications requiring both electrical conductivity and hardness.
• SiC13N14 presents potential for applications demanding extreme hardness and semiconducting behavior.