Revealing correlation of core‒rim structures, defects and stacking-faults in SiC ceramics by integrated scanning electron microscopy. Issue 1 (January 2021) - Zhao, Ting-Ting
Abstract: Dopant distribution is key to understand sintering behavior and microstructure‒property relationship of silicon carbide (SiC) ceramics. Using high-angle secondary-electron (SE) imaging in scanning electron microscope combining elemental and cathodoluminescence (CL) analysis, core‒rim structures were found as common microstructural features in SiC ceramics sintered with rare-earth oxides. Characteristic emission by donor-accepter-pairs (DAP) could reveal co-solution of Al‒N in α- and β-SiC phases in hot-pressed and gas-pressure sintered ceramics, with or without AlN co-dopant. Stacking-faults (SFs) were found in β-SiC grains to emit characteristic photons by local twin-structures, which confine the luminous transition by DAP into a quantum effect and suppress fully the luminescence when SF density reaches a limit by sintering with two rare-earth oxides. Systematic correlation between the development of microstructures, solution and defect luminescence, and phase transformation can lead to hierarchical microstructure‒property relationship to study synergetic mechanical, thermal and opto-electrical performance of SiC ceramics as well as electronic materials.