Electronic and dielectric properties of rare‐earth oxides in visible and near‐infrared range: A first‐principles study

Abstract The widespread application of laser technology has increased the demand for laser‐protective materials, and rare‐earth oxides are potential materials in laser protection research due to their unique physical and optical properties. This study investigates the electronic structure, dielectric, and optical properties of a series of cubic rare‐earth sesquioxides (RE 2 O 3 , RE = Gd, Dy, Er, Yb, Lu, Sc, and Y) using first‐principles calculations. The dielectric and optical properties of RE 2 O 3 materials in the visible‐to‐near‐infrared (VIS‒NIR) wavelength range are clarified to be governed by electronic transitions. Despite similar spectral characteristics, the peaks in the spectra of dielectric function, complex refractive index, reflectance, and absorption coefficient systematically exhibit blue shifts with increasing RE 3+ cationic radius in the same group, or decreasing RE 3+ cationic radius in the same period, which is inherited from the variation in band gap size. And, a guideline to search for RE 2 O 3 materials with high reflectance in the NIR wavelength range is proposed to be correlated with high refractive index and low band gap. These findings elucidate the fundamental mechanisms governing the dielectric and optical properties of rare‐earth oxides within the VIS‒NIR range, and provide useful guidelines for the screening and optimizing RE 2 O 3 ‐based materials for laser‐protective applications.