A strategy for low thermal conductivity of lutetium oxyorthosilicate ceramics fabricated via texture engineering

Submicrometer lutetium-gadolinium oxyorthosilicate ((Lu0.95Gd0.05)2SiO5, LGSO) powder with a magnetic susceptibility of 4.19 x 10-6 (5.4 times that of lutetium oxyorthosilicate) was synthesized via a sol-gel method. Slip casting with a 6 T assisted magnetic field and pressureless sintering at 1600 degrees C for 16 h in the air effectively produced the textured LGSO ceramics with an orientation factor f of 0.96. The grains of textured LGSO ceramics grow with the preferred orientation along the b-axis. The thermal conductivity of the textured LGSO ceramics reaches only 2.05 W center dot m-1 center dot K-1 at 300 K, which is 34.5% lower than that of untextured LGSO ceramics. Textured LGSO ceramics provide increased fracture toughness. This work presents a microstructural design method for RE2SiO5 ceramics to regulate thermal and mechanical properties through texture engineering, as well as advice for the selection or optimization of RE2SiO5 ceramics as a Thermal Barrier Coatings (TBCs) material.