Electron traps in Tb3+-doped CaAl2O4

Tb3+-doped CaAl2O4 samples were prepared and studied. The 5D3,4 to 7FJ (J=6, 5, 4,…) afterglow emissions of Tb3+ with a persistence time of 1 h are observed. Photoconductivity experiment determined that the ground state of Tb3+ is 0.4 eV above the top of the CaAl2O4 valence band. Two thermoluminescence peaks (−3 and 114 °C) and two thermal stimulated current peaks (−5 and 119 °C) were also detected. The results indicated that the traps at −3 °C (1.08 eV) are close to Tb3+ emission centers, while the traps at 114 °C (0.66 eV) are far away from the centers.