Photoluminescent behavior of SrB4O7:RE2+ (RE=Sm and Eu) prepared by Pechini, combustion and ceramic methods

This work reports the preparation of system containing RE2+ ions (RE=Sm and Eu)-doped in SrB4O7 matrix by ceramic, Pechini and combustion methods. These compounds were prepared by reduction of RE3+ to RE2+ in air, which exhibit some different features according to the preparation method. Photoluminescent properties of these systems were investigated based on the emission and excitation spectral data. The emission spectra of SrB4O7:Eu2+ system prepared by combustion and Pechini methods are characterized by a broad band assigned to interconfigurational 4f65d→4f7 transition, while SrB4O7:Sm2+ compound exhibit narrow emission bands arising from intraconfigurational-4f6 also shows 4G5/2→6HJ′ transitions (image and image) arising from Sm3+ ion, transitions. SrB4O7:RE system prepared by combustion method presents emission bands from RE3+ ions as intense as that arising from RE2+, suggesting that the preparation route is not efficient for the reduction RE3+→RE2+ process. Emission quantum efficiency and radiative emission rates of Sm2+ ion are determined and discussed.