High-entropy (YErYbLu)2SiO5 ceramic aerogel: A potential ceramic insulator with low thermal conductivity

• Published in: Ceramics international 2024-01, Vol.50 (1), p.1795-1806
• Main Authors: Wang, Jie, Wang, Wei, Liu, Xuening, Shang, Sisi, Chen, Yuting, Shi, Lingyan, Cui, Sheng
• Format: Article
• Language: English
• Subjects: Aerogel; High-entropy ceramic; Rare earth mono silicate; Thermal expansion; Thermal insulation
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2023.10.279

Conventional oxide aerogels have limitations in terms of structural damage and phase transformation at high temperatures. A novel high-entropy (YErYbLu)2SiO5 ceramic aerogel was synthesized by a combination of the sol-gel process, supercritical drying, and high-temperature calcination. The successful synthesis of a high-entropy (YErYbLu)2SiO5 ceramic aerogel in a single phase after calcination at 1250 °C was confirmed by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The high-entropy ceramic aerogel (YErYbLu)2SiO5 still shows excellent structural and phase stability after annealing at 1400 °C. The structurally reconstructed samples (RSO) exhibit low densities ranging from 1.79 to 3.28 g cm−3, room-temperature thermal conductivities between 0.109 and 0.253 W·m-1 K-1, and fracture toughness values ranging from 0.61 to 9.70 MPa. Notably, the lowest thermal conductivity is less than 1/10 of that of the corresponding dense crystalline ceramics. Furthermore, the RSO has a low coefficient of thermal expansion within the temperature range of 360–1200 °C (ranging from 5.84 × 10−6 °C−1 to 7.36 × 10−6 °C−1). The RSO exhibits high residual strength retention after thermal shock testing. These properties position the high-entropy (YErYbLu)2SiO5 ceramic aerogel as a promising candidate for nano-thermal insulation as a porous ceramic material that undergoes structural reconstruction.