Thermophysical properties of Yb(Ta Nb1−)O4 ceramics with different crystal structures

Monoclinic (m) and monoclinic-prime (m′) phases of Yb(TaxNb1−x)O4 ceramics were synthesized successfully, and the relationships between the crystal structures and the thermophysical properties were investigated by various methods. A ferroelastic domain existed in the m-Yb(TaxNb1-x)O4 ceramics, as observed by a scanning electron microscopy, which suggests that a ferroelastic phase transition occurred. The minimum thermal conductivity of the Yb(TaxNb1−x)O4 ceramics was 1.49 W m−1·K−1, whereas the maximum thermal expansion coefficient (TEC) was 10.6 × 10−6 K−1 (1200 °C). The m-phase had a lower Young's modulus (110–132 GPa) than the m′-phase (133–140 GPa). In view of the low thermal conductivity and high TEC, Yb(TaxNb1−x)O4 ceramics have the potential to be high-temperature structural ceramics.