Fabrication of high‐performance colored silicon nitride ceramics using Er ₂ O ₃ –MgO additives

This work aimed at investigating the effect of different Er 2 O 3 content on the mechanical properties and coloration of silicon nitride ceramics. All samples were prepared by gas pressure sintering at 1800°C for 2 h. The addition of Er 2 O 3 led to a denser microstructure consisting of distinctive rod‐like Si 3 N 4 grains with higher aspect ratio, with the fracture toughness and flexure strengths as 10.77 ± 0.08 MPam 1/2 and 970 ± 27 MPa, respectively. The chromaticity of sintered samples was measured by spectrophotometer. With the increase of Er 2 O 3 content, the color of pink‐orange Si 3 N 4 ceramics was gradually getting darker. Scanning transmission electron microscope (STEM) results showed that core–shell structures existed in the β‐Si 3 N 4 matrix, and the core and shell were pore and Er‐rich liquid phase, respectively, which served as the chromogenic center in Si 3 N 4 ceramics. Results showed that the combination of Er 2 O 3 with MgO was effective for the development of Si 3 N 4 ceramics with pink‐orange color and high mechanical properties.