The effect of melt-homogenization and heat-treatment on the optical properties of the rare earth doped oxyfluoride glass-ceramics

•Four precusor Er-Yb doped oxyfluoride glasses were prepared via melt-quenching.•These glasses were obtained at different melt-homogenization temperatures (Thomo).•Melt heterogenity increases by lowering Thomo, and crystal formation gets easier.•Light transmittance (LT) drops with lowering Thomo but UC luminescence is enhanced.•Heat-treatment enhances the UC luminescence, but shows a nonmonotonic LT change.