Eu2+ doped calcium aluminates prepared by alternative low temperature routes

Abstract

Eu 2+ doped calcium aluminates, CaAl 2 O 4 :Eu 2+ , were prepared by the Pechini and combustion methods. Very pure monoclinic CaAl 2 O 4 :Eu 2+ was obtained by Pechini method when annealed at 1250 °C. The reaction time was shortened but the annealing temperature was the same as that of the conventional solid state method. By using the combustion method, an additional annealing at 900-1100 °C was needed to crystallize the initially amorphous material. An unusual hexagonal polymorph was then obtained. The luminescence band of the Pechini prepared CaAl 2 O 4 :Eu 2+ peaking at 440 nm corresponded to that of the solid state prepared material. Persistent luminescence spectrum was the same as that of the UV excited one. The thermoluminescence glow curve position, i.e. the nature of lattice defects was not observed to depend significantly on the preparation method.