Tb-doped YPO4 phosphors: Polyacrylamide gel synthesis and optical properties

Abstract

Single phase of Tb-doped YPO4 phosphors with xenotime structure were successfully synthesized via a polyacrylamide gel at different annealing temperatures (650–1050 °C). The crystal structure, thermal behavior and optical properties of the as-synthesized samples were investigated by XRD, TG-DTA, FT-IR, PL, and XPS. The effects of heat treatment on the structure and luminescence properties of samples were discussed. The PL spectra results reveal that the annealing temperature plays a key role in the luminescence properties of products. The samples obtained under 650–850 °C exhibit a strong green emission at 546 nm, attributing to the 5D4-7F5 transition of Tb3+, while the samples produced above 850 °C emit dominating blue lines at 381 and 415 nm, corresponding to the 5D3-7F6 and 5D3-7F5 transitions, respectively. The XPS results imply that a part of doping Tb3+ ions may be oxidized to Tb4+ on the high-temperature thermal treatment process, which could be the reason for the bluish color of Tb-doped YPO4 phosphors.