Composition regulation and property enhancement of (LaxY1-x)2Zr2O7 thermal insulation materials

Thermal insulation materials with low thermal conductivity and high near-infrared (NIR) reflectance are required for high-temperature environments above 1000°C to enhance energy efficiency. Recently, rare-earth zirconates have attracted significant attention due to their high-temperature stability, low thermal conductivity and good corrosion resistance. However, research on the near-infrared reflection performance of Y 2 Zr 2 O 7 -La 2 Zr 2 O 7 solid solution systems for high-temperature energy-saving applications remains limited, and a systematic study on composition regulation and performance as high-temperature thermal insulation materials is needed. In this work, (La x Y 1-x ) 2 Zr 2 O 7 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) nano-powders were synthesized using a low-temperature solid-state reaction method, and the effects of cation substitution on the microstructure, NIR reflectance, and thermal conductivity were investigated. The results showed a phase transition from fluorite to pyrochlore as x increased. The biphasic coexisting structure inhibited grain growth, which enhanced NIR reflectance and reduced thermal conductivity. When x = 0.7, the combined effects of biphasic coexisting, lattice distortion, and defects resulted in materials with a high NIR reflectance of 91.73% and low thermal conductivity of 1.4 W/m·K, demonstrating promise for high-temperature energy-saving applications.