On the Quenching of Bi3+ Luminescence in the Pyrochlore Gd2GaSbO7

The luminescence of Bi3+ in the pyrochlore Gd2GaSbO7 is evaluated in the 15 to 300 K temperature range. The rapid thermal quenching of Bi3+ luminescence, despite the small Stokes shift, is postulated to involve a photoionization process arising from the interaction between the Bi3+3P0, 1 excited states and the host lattice conduction band. The blue emission of the host lattice is attributed to the octahedral gallate groups of Gd2GaSbO7. The Bi3+ luminescence Gd2GaSbO7, La2Zr2O7 (pyrochlore structure), Y2O3 (fluorite structure), and materials with the perovskite structure are compared to gain insight into structurephotoionization issues.