Synthesis of Sc₂W₃O₁₂/ZrO₂ composites with controllable thermal expansion

Sc₂W₃O₁₂, which exhibits excellent anisotropic negative thermal expansion was synthesized using solid-state reaction. Sc₂W₃O₁₂/ZrO₂ composites were prepared by mixing ZrO₂ and Sc₂W₃O₁₂ at different volume ratios and sintered at 1200 ℃ for 10 h. The crystal structure, fracture surface morphology and thermal expansion properties of the synthesized samples were characterized by XRD, SEM, EDS and dilatometer. The results indicate that the obtained samples contain only orthorhombic Sc₂W₃O₁₂ and monoclinic ZrO₂ phase. All the thermal expansion properties of Sc₂W₃O₁₂/ZrO₂ composites are linear from 30 ℃ to 600 ℃, and their thermal expansion coefficients can be controlled as positive, negative or even zero by adjusting the volume fraction of Sc₂W₃O₁₂. 60%Sc₂W₃O₁₂/ZrO₂ composite shows almost zero thermal expansion, and its average thermal expansion coefficient is 0.026×10^-6 ℃^-1 from 30 ℃ to 600 ℃.