Luminescence-switching behaviors of CePO4:Tb3+ upon redox reactions were examined using KMnO4 and l(+)-ascorbic acid as an oxidant and a reductant, respectively. Powdery nanorod-like CePO 4:Tb3+ particles were synthesized by liquid-phase reactions of rare-earth ions and phosphate ions in aqueous solutions at low temperatures. According to X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy, the oxidizing treatment of CePO4:Tb3+ was found to bring about partial oxidation of Ce3+ to Ce4+ and a small degree of structural damage in the particle surface, which could be recovered by the subsequent reducing treatment. Photoluminescence (PL) intensity of CePO4:Tb3+ due to 5D4 → 7FJ (J = 3-6) electronic transitions of Tb3+ was decreased with increasing KMnO4 concentration in an exponential manner, resulting from excitation cutoff by an intervalence Ce3+ → Ce4+ charge transfer and emission cutoff by a Ce3+ absorption red-shifted to the visible region. Reversely, PL intensity was increased also in the exponential manner by increasing the l(+)-ascorbic acid concentration in reducing the previously oxidized CePO4:Tb3+, thereby achieving the quantitative, repetitive luminescence switching. Our results demonstrate that the luminescence switching is regarded as a surface phenomenon without a whole change of structure and valence in the CePO4:Tb 3+ material.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films