Synthesis and thermophysics properties of ferroelastic SmNb1-XTaXO4 ceramics

Monoclinic phase SmNb 1-X Ta X O 4 ceramics are synthesized via solid-state reaction. X-ray diffraction and Raman spectra are applied to characterize the crystal structure. The ferroelasticity of SmNb 1-X Ta X O 4 ceramics is confirmed by the domain structure observed via scanning electron microscopy. The band gap of SmNb 1-X Ta X O 4 ceramics ranges from 4.3 to 5.0 eV and they exhibit excellent absorption for UV light. Thermophysics properties including specific heat, thermal diffusivity , thermal conductivity and thermal expansion coefficients of SmNb 1-X Ta X O 4 ceramics are investigated systematically. The result shows that the thermal conductivity of SmNb 1-X Ta X O 4 ceramics is as low as 1.33 W m −1 K −1 (900 °C) and the thermal expansion coefficients are as high as 11.7 × 10 −6 K −1 (1200 °C). The unique ferroelasticity and outstanding thermophysics properties indicate that SmNb 1-X Ta X O 4 ceramics are promising thermal barrier coating materials.