Y2O3 is widely used in IR windows and optoelectronics, but its vibrational and spectral properties under La3+ substitutions remain unclear. This work investigates xLa2O3-(1−x)Y2O3 with x = 0–0.2 via XRD, SEM, Raman, and IR spectroscopy to address the lack of comprehensive data on structure–property correlations. The solid solution (Y1−xLax)2O3 with 0 ≤ x 0. The Raman modes and IR modes of (Y1−xLax)2O3 show red shift and obvious peak broadening as x increases, which is caused by the expansion of unit cell and local distortions of the crystal structure. As Y3+ is substituted by La3+, the extinction coefficient κ decreases significantly, which can lead to a lower IR absorption and should be beneficial for the IR window applications.
Zhang et al. (Fri,) studied this question.