Synergistic regulation of color and mechanical properties of silicon nitride ceramics via engineering hollow structures of Eu-enriched secondary phases

Si3N4 ceramics, renowned for their superior mechanical properties, are widely regarded as the most promising materials for electronic device casing. This is particularly evident in the context of 5th generation mobile networks, where they outperform both glass and zirconia. However, achieving a synergetic balance between color and mechanical properties remains a significant challenge. In this study, we propose the use of phase separation in liquid phases, supported by a novel Eu2O3-YAG-MgO system, to engineer hollow structures. This approach aims to achieve high-toughness colored Si3N4 ceramics. The resulting hollow structure not only acts as a reinforcing phase in response to the stress field caused by lattice mismatch but also serves as one of the dominant chromophores. This is achieved through the 5d→4f transition of Eu2+ coupled with the 5D0→7FJ transition of Eu3+ under photon excitation. These findings offer new insights into the development of high-performance Si3N4 ceramics with well-controlled color.