Effect of flux on the properties of CaAl2O4:Eu2+, Nd3+ long afterglow phosphor

The long afterglow phosphor CaAl2O4:Eu2+, Nd3+ was prepared by high temperature solid-state reaction method under reducing atmosphere. The effect of flux H3BO3 on the crystal structure and luminescent properties of the phosphor was studied. Results of XRD indicate that the volume of unit cell becomes smaller, and then the crystal field is changed, which results in the easier transition of 4f-5d. On the other hand, H3BO3 addition is in favor of the formation of pure phase CaAl2O4. Both behaviors enhance the emission intensity of the obtained phosphor to some extent. But its emission peak does not shift evidently because the energy level difference of 4f-5d does not be changed obviously. Moreover, H3BO3 also affects the afterglow properties of this phosphor. The optimized content of H3BO3 is 0.06 mol/mol for the obtained phosphor with excellent properties. (C) 2007 Elsevier B.V. All rights reserved.