Synthesis and thermophysics properties of ferroelastic SmNb1-XTaXO4 ceramics

Monoclinic phase SmNb1-XTaXO4 ceramics are synthesized via solid-state reaction. X-ray diffraction and Raman spectra are applied to characterize the crystal structure. The ferroelasticity of SmNb1-XTaXO4 ceramics is confirmed by the domain structure observed via scanning electron microscopy. The band gap of SmNb1-XTaXO4 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 SmNb1-XTaXO4 ceramics are investigated systematically. The result shows that the thermal conductivity of SmNb1-XTaXO4 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 SmNb1-XTaXO4 ceramics are promising thermal barrier coating materials.