Wydział Chemii

Joanna Trojan-Piegza

J. Niittykoski

J. Hölsä

Eugeniusz Zych

2008

Chemistry of Materials

20

2252-2261

10.1021/cm703060c

Naukowa

Angielski

Artykuł

The properties of green thermoluminescence (TL) and persistent luminescence of Lu₂O₃:Tb³⁺ and Lu₂O₃:Tb³⁺,Ca²⁺ materials sintered in vacuum at 1700 °C were investigated. The concentration of Tb varied in the range 0.1–3 mol %, and the Ca content was 1 mol %. Ca²⁺ codoping enhanced the room temperature persistent luminescence intensity and its duration as well as reduced the number of TL bands for lightly doped materials from four components covering about 50–400 °C range of temperatures to only one peaking around 100 °C. The Tb³⁺,Ca²⁺ (0.1 and 1 mol %, respectively) codoped material showed the most efficient persistent luminescence and TL, originating mainly from the ⁵D₄ → ⁷F₅ transition at around 545 nm, among all the compositions investigated. For this material the persistent luminescence could be observed in the dark for about 15 h. There are indications that the efficient persistent luminescence of the codoped system is governed by tunneling mechanism, and the trapping centers are postulated to be [Tb_Lu^×−V_O^••−2Ca_Lu^ˈ] aggregates. Oxygen vacancies are supposed to serve as traps for free electrons giving F⁺ (e_O^••) or F (V_O^×) centers while holes are temporarily immobilized in the vicinity of Tb_Lu^× giving [Tb_Lu^×−h^•] entities. Alternatively, hole can be trapped in the Ca_Lu^ˈ site due to its negative net charge, giving [Ca_Lu^ˈ−h^•]. Air-sintered specimens did not show any significant persistent luminescence or TL, although they produce quite significant photoluminescence. Also, vacuum sintering at lower temperatures—1600 °C and below—was not sufficient to get efficient persistent luminescence.

luminescence, Defects, materials, irradiation, Ions

https://doi.org/10.1021/cm703060c

https://www.acs.org/content/acs/en.html