Thermal Property of Y_4.67(SiO₄)₃O Ceramic Sintered from Hydrothermally Synthesized Spindle-like Y_4.67(SiO₄)₃O Apatite Crystallites

Spindle-like Y 4.67 (SiO 4 ) 3 O apatite crystallites composed of numerous nanoparticles with a mean diameter of about 50 nm were synthesized via a facile hydrothermal method at 503 K for 12 h.To the best of our knowedge, the thermal properties of the spindle-like Y 4.67 (SiO 4 ) 3 O apatite crystallites was firstly reported.Their phase composition, microstructure, formation mechanism were investigated.Results show that hydrothermal temperature greatly influences the crystal phase composition and the crystal morphology.In addition, the obtained Y 4.67 (SiO 4 ) 3 O ceramics possess low thermal conductivity and a relatively high thermal expansion coefficient, which make them a promising candidate material for environmental/thermal barrier coatings.