Influence of TiO₂ doping on thermo-optical properties of pyrochlore Sm₂(Zr_1–xTi_x)₂O₇ (0≤x≤0.15) ceramics

Sm₂(Zr_1–xTi_x)₂O₇ (0≤x≤0.15) ceramics have been fabricated by pressureless-sintering method at 1973 K for 10 h in air. The influence of TiO₂ doping on microstructure and thermo-optical properties of Sm₂(Zr_1–xTi_x)₂O₇ ceramics is investigated by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. The partial substitution of Ti⁴⁺ for Zr⁴⁺ results in a significant increase in emissivity at low wavelengths contrasted with undoped Sm₂Zr₂O₇. Sm₂(Zr_0.85Ti_0.15)₂O₇ ceramic exhibits a high emissivity of above 0.70 at 1073 K in a wavelength range of 3–16 µm, where the highest value at this temperature is more than 0.90 especially in the wavelength range of 9–14 µm. FT-IR spectra and optical absorption spectra unveil the mechanisms of enhanced emissivity in Sm₂(Zr_1–xTi_x)₂O₇ (0.05≤x≤0.15) ceramics in the intermediate infrared range, especially at the wavelengths of 3–8 µm, due to Ti⁴⁺ ion substitution for Zr⁴⁺ ion.