Solid loading-dependent mechanical and thermal insulation properties of 3D-printed high-entropy fluorite (Ce0.2Zr0.2Ti0.2Sn0.2Ca0.2)O2-δ ceramic

Fabricating high-performance high-entropy ceramics (HECs) with complex geometries remains a challenge. Here, high-entropy fluorite (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Ca 0.2 )O 2-δ ceramics were fabricated by digital light processing (DLP). The effects of slurry solid loading (76–80 wt%) on sintering behavior, microstructure, mechanical properties, and thermal transport were systematically investigated and compared with pressureless sintering. Increasing the solid loading to 80 wt% increased the green-body density, reduced linear shrinkage, and produced ceramics with a bulk density exceeding 5.0 g/cm³ (>88% theoretical density). EDS analyses revealed compositionally homogeneous microstructures without detectable micron-scale elemental segregation within the spatial resolution of the present measurements. DLP-80 HEFO exhibited the highest flexural and compressive strengths among the printed samples while maintaining low thermal conductivity values of 1.7–2.2 W·m⁻¹ ·K⁻¹ from 25 to 1000 °C. This work demonstrates that optimizing slurry solid loading provides an effective strategy for fabricating high-entropy fluorite ceramics with balanced densification, mechanical performance, and thermal-insulation capability.