Realizing mechanical property improvement and coloration in Si3N4 ceramics by rare earth-doping

Si3N4 ceramics, due to their exceptional comprehensive performance, have potential applications in electronic products under the 5th generation mobile communication technology. However, their development is hindered by a lack of color variety and inherent brittleness. To address these issues, we propose the use of an appropriate colorant-sintering additive to enhance densification, promote the growth of β grains and facilitate the formation of a chromogenic phase. This approach aims to simultaneously adjust the color and mechanical properties of Si3N4 ceramics. STEM-EDS results indicate the presence of Re-enriched hollow structures within the Si3N4 matrix. These hollow structures may serve as one of the color centers of silicon nitride. The combined effects of the stress field surrounding the hollow structure, elongated β-Si3N4 grains and intensive dislocations result in strong mechanical properties of Si3N4 ceramics, in which the flexural strength is 852.7 ± 55.8 MPa and the fracture toughness is 11.7 ± 1.0 MPa m1/2.