Effect of ZnO on absorptivity and emissivity of corundum‐spinel composite ceramics for solar thermal power generation

Abstract In solar thermal power generation (STPG) systems, materials with high absorptivity and low emissivity are essential for efficient solar radiation capture and minimal thermal energy loss. This study explores the impact of ZnO on the optical properties of corundum‐spinel composite ceramics. A material with high absorptance (92.60%) and low emittance (80.72%) was developed, showing excellent thermal shock resistance. The ZnAl 2 O 4 formed from ZnO and Al 2 O 3 enhances light absorption through electron transitions. Additionally, ZnAl 2 O 4 suppresses grain growth, reducing grain size and increasing phase boundaries, promoting light scattering and extending photon transport paths. These structural changes, along with defect sites, further boost absorptivity. ZnAl 2 O 4 also reduces mid‐infrared emissivity, lowering overall infrared radiation. The material's combination of high absorptivity, low emissivity, and thermal stability makes it a strong candidate for STPG applications.