Theoretical Study on the Relationship Between Crystal Chemistry and Properties of Quaternary Y–Si–O–N Oxynitrides |
| |
| Authors: | Luchao Sun Bin Liu Jiemin Wang Zhen Li Jingyang Wang |
| |
| Affiliation: | 1. High‐performance Ceramics Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China;2. School of Materials Science and Engineering, Shanghai University, Shanghai, China |
| |
| Abstract: | Y–Si–O–N quaternary oxynitrides (Y5Si3O12N, Y4Si2O7N2, YSiO2N, Y2Si3O3N4, and Y3Si5ON9) are recognized as important secondary grain‐boundary phases in silicon nitride and believed to have important impacts on the high‐temperature mechanical properties and thermal conductivity of Si3N4 ceramic. In this work, equilibrium crystal structures, theoretical mechanical properties (second‐order elastic constants, polycrystalline bulk modulus, shear modulus, Young's modulus, and Vickers hardness) of the five quaternary phases are calculated using first‐principle total energy calculations. Meanwhile, temperature dependence of thermal conductivities of all five compounds is obtained based on Debye–Clarke model and Slack equation. On the basis of theoretical prediction, we establish the relationship between the componential (cation/anion or cation/cation ratios) and structural characteristics (bonding configurations) and mechanical/thermal properties. Our results are expected to provide helpful guidelines to improve the performances of Y–Si–O–N ceramics, and further guide the optimization of mechanical and thermal properties of Si3N4 by properly tailoring the secondary grain‐boundary phases. |
| |
| Keywords: | Oxynitride first‐principles calculation mechanical property thermal conductivity |
|
|
