Preparation of LiTaO3:Tb3+ bulk nanoceramics and persistent luminescence revealed by thermal- and electric-driven hopping of defects

Bulk ceramics of afterglow phosphors are preferred for real applications with applied external stimuli like electric field, force and heat. However, sintering powdered afterglow phosphors with high-temperature-volatile components to bulk form normally leads to deterioration or even loss of persistent luminescence (PersL), such as the case of LiTaO 3 :Tb 3+ . This study adopted a strategy of using nanosized precursors prepared by exfoliation and molten salts methods for the subsequent sintering procedure to form LiTaO 3 :1 mol% Tb 3+ bulk nanoceramics, which show outstanding PersL compared to bulk microceramics with absence of PersL. The dynamics of carriers, including electrons, holes and non-static V Li defects were detailedly investigated in the charging process of the bulk nanoceramics at elevated temperatures. It is found that defects not only act as traps storing and releasing electron-hole carriers, but also function as carriers themselves in the LiTaO 3 :1%Tb 3+ bulk nanoceramics. Temperature-dependent electricity and luminescence verify the hopping process of Li + / V Li above 225 °C . The hopping leads to accelerated release of holes initially captured by V Li and the subsequent non-radiative recombination with electrons from V O . It features an apparent and significant intensity decline during the charging process compared to low temperatures or cases without PersL. The bulk nanoceramics possess a temperature-triggered capability for anti-counterfeiting and information storage. These findings contribute to a strategy to fabricate bulk ceramics which are sensitive to sintering procedure, and provide valuable insights into the underlying mechanisms and the rational design of PersL materials.