UV-sensitized Sm³⁺ visible and near-IR photoluminescence in phosphate glass melted with multi-wall carbon nanotubes

Phosphate glass doped with Sm³⁺ ions was prepared by melting in ambient atmosphere with multi-wall carbon nanotubes (MWCNTs) added to batch materials to evaluate their impact on material optical properties. An enhanced UV transparency occurs similar to that of a glass melted just with MWCNTs. However, the glass melted only with MWCNT shows evidence of carbon-related luminescent defects, whereas the luminescence of these becomes suppressed in the Sm³⁺-doped glass melted with the MWCNTs. A comparison with the photoluminescence (PL) of a Sm³⁺-doped reference (i.e., not melted with MWCNTs) shows that addition of MWCNTs produces an improvement in Sm³⁺ PL in the visible and near-IR regions. The enhanced PL is observed for resonant excitation in the UV and non-resonantly under 300 nm excitation. It is suggested that the reduced host absorption contributes to the improved PL for resonant excitation of Sm³⁺ in the UV, while the non-resonant pathway may be related to an energy transfer from the luminescent defects produced in the host. It is the first time to our knowledge that this type of sensitized emission is reported.