Excitation-dependent photoluminescent properties in geopolymers with addition of Eu2+ Dy3+ co-doped strontium silicoaluminate

Optical properties of blast furnace slag based geopolymers synthesized at 60 degrees C with additions of 4, 12 and 20% of Sr2.9Eu0.03DY0.07Al4SiO11 (SEDASO) are studied. In the photoluminescence spectra, the geopolymers exhibit two broad emission bands: in the blue region (persistence at 490 nm) due to 4f(6) 5d(1) -> 4f(7) transitions of Eu2+ and in the red region (at 634 nm), produced by the Mn2+ and Fe3+ present in the geopolymer matrix, generating excitation-wavelength dependent emissions. The quantum yield of emission is enhanced 80% when SEDASO additions are increased from 4% to 20%, with maximum times of light persistence of 233 s. The formation of a micro-interface between the geopolymer matrix and SEDASO is established by means of SEM analysis, which favors stability in the paste, and simultaneously allows greater interaction between incident light and SEDASO. It is envisioned that these emission properties in geopolymers could be used for application in the construction industry, i.e., as luminescent pavement. (C) 2019 Elsevier B.V. All rights reserved.