In-situ Insights into trap attributions in Fe3+-activated long persistent phosphors

Here, a novel NIR afterglow center of Fe3+ is proposed, and a long persistent phosphor of SrAl12O19: Fe3+ is successfully fabricated. Some in-situ characterizations, including temperature-dependent electron paramagnetic resonance (EPR) spectra and thermoluminescence (TL) spectra of Al2O3 and SrCO3 raw materials, support the fact that the substitution of Fe3+ to Al3+ creates a trap with the negative effective charge by binding an electron around [AlFe]. Further, the existence of isoelectronic trap-cluster (AlFe-VO) endows a bright emission band that appeared in the range of 750–1000 nm with an afterglow duration of >2 h. Notably, these analyses in the aspect from the influence of raw materials on afterglow properties are very rarely found in the searchable reports. This top-down investigation route reveals the possibility of perfecting the research skills on the afterglow mechanism from the fountainhead and may offer a wide-range understanding of the trapping and de-trapping process of long persistent phosphors.