Synthesis, crystal structure and thermophysical properties of (La1-XEuX)3TaO7 ceramics

Rare earth tantalates (La1-XEuX)3TaO7 ceramics are synthesized via solid-state reaction in this work. The phase structure is characterized via X-ray diffraction and Raman spectrum, when the microstructure and element distribution are detected by scanning electron microscopy and energy dispersive spectroscopy. As for various properties, (La1-XEuX)3TaO7 ceramics own excellent absorption for the UV light and the band gap ranges from 4.0 to 4.7 eV. The highest thermal expansion coefficients reach 10.8 × 10−6 K−1 (1200 ℃) and the entire series of (La1-XEuX)3TaO7 ceramics exhibit excellent high-temperature phase stability. The minimum thermal conductivity reaches 1.04 W m−1 K−1 (500 ℃) ascribed to various phonon scattering mechanisms. The thermal radiation resistance relates to the crystal structure, which relies on the mean RE3+ ionic radius. The results reveal that (La1-XEuX)3TaO7 ceramics are candidate thermal insulation materials.