Cross Relaxation in rare-earth-doped oxyfluoride glasses

► Tb3+, Sm3+, and Eu3+ were doped into a LaF3-rich oxyfluoride glass. ► The 5D3 cross relaxation rate of Tb3+ can be tuned via concentration. ► The 5D3/5D4 emission intensity ratio was used as a probe for Tb3+ ion aggregation. ► Cross relaxation dominates the decay of the 4G5/2 excited state of Sm3+. ► Multiple Eu3+ sites yield a non-exponential 5D0 decay via 5D0→7F2 hypersensitivity.