Boson peak and structural heterogeneity in ternary SiO ₂ ‐Al ₂ O ₃ ‐B ₂ O ₃ glasses

Abstract

Abstract We use low‐temperature heat capacity, low‐frequency Raman scattering, and THz time domain spectroscopy in order to scale the vibrational density of states and the Boson peak in SiO 2 ‐Al 2 O 3 ‐B 2 O 3 Yb‐laser host glasses. When substituting B 2 O 3 for SiO 2 at constant Al 2 O 3 dopant level, we find an optimal value for the ratio of B/Al in terms of mixture stability, at which the excess in the electron donor capability of Al 2 O 3 (relative to the SiO 2 backbone) is compensated by the more acidic B 2 O 3 . At this composition, Al 2 O 3 plays a mediating role in the structure of aluminoborosilicate glasses, facilitating dissolution of Yb 2 O 3 and admixture of B 2 O 3 into the SiO 2 network.