Laser-Activated Luminescence of BaAl 2 O 4 :Eu

Abstract

In this article the laser-activated (LA) luminescence of BaAl 2 O 4 doped with 3 mol% Eu 2+ and SrAl 2 O 4 doped with 700 ppm Eu 2+ is described. The LA spectrum of BaAl 2 O 4 :Eu did not show any emission from Eu 2+ , but rather luminescence from the Eu 3+ ion. This surprising result is explained in terms of ionization of the excited Eu 2+ ions (photo-ionization), while the freed electrons are trapped in an excited state of the F-centre: this is considered to be a deep trap. The temperature of the ferroelectric-paraelectric phase transition in BaAl 2 O 4 has been determined at ≈180 °C from the Raman spectra recorded at various temperatures.