A first principles study on optical transparency mechanism in Dy doped α-SiAlON ceramics

Dy doped α-SiAlON ceramics prepared by the hot-pressing method show a high optical transmittance value, >70%, in the infrared region of 1.5–4.5 μm. First principles calculations have been carried out to reveal the underlying transparency mechanism. It is found that the valence shell of doped Dy atoms interacts strongly with the doping states of α-SiAlON, resulting in the increase in the optical gap from 0.4 to 1.1 eV, which suppresses the photoabsorption in the wavelength region longer than 1.0 μm and leads to the good transparency property. The calculated optical transmission spectra are in good agreement with the corresponding experiments.