Ceramics-Silikáty 49 (1) 58-62 (2005)

Luminescence properties of Eu²⁺ doped dibarium magnesium disilicate, Ba₂MgSi₂O₇:Eu²⁺

T. Aitasalo, J. Hölsä, T. Laamanen, M. Lastusaari, L. Lehto, J. Niittykoski, F. Pellé

A new persistent luminescence material, monoclinic Ba₂MgSi₂O₇:Eu²⁺, was prepared by a solid state reaction. Both the UV excited and persistent luminescence are observed at the green region centred at 505 nm. Both luminescence phenomena are due to the same Eu²⁺ ion occupying the single Ba²⁺ site in the lattice. The R³⁺ co-doping (R is rare earth) usually enhances the persistent luminescence of Ba₂MgSi₂O₇:Eu²⁺. Especially, the Tm³⁺ ion has a very strong effect. Two thermoluminescence peaks at 90 and 130°C are observed in the glow curve of Ba₂MgSi₂O₇:Eu²⁺, which is nearly ideal for a persistent luminescence material. The persistent luminescence is probably due to lattice defects i.e. oxygen (cation) vacancies, which create trapping levels for electrons (holes). Recombination of the electron-hole pair and energy transfer to the Eu²⁺ ion complete the probable persistent luminescence mechanism. The details of the mechanism(s) need, however, more experimental work to be carried out. The stable disilicate materials are very good candidates for the persistent luminescence materials as alternatives to the Eu²⁺ doped alkaline earth aluminates.

Keywords: Dibarium magnesium disilicate, Europium, Persistent luminescence