EPR study of Ce3+ ions in lutetium silicate scintillators Lu2Si2O7Lu2SiO5

Two Ce3+-doped scintillatorcrystals, LSO (Lu2SiO5:Ce) and LPS (Lu2Si2O7:Ce), are studied by EPR spectroscopy. The analysis indicates that Ce3+ substitutes for Lu3+ ion in a C-2-symmetry site for LPS and in two C-1-symmetry sites for LSO, with a preference for the largest one, with 6+ 1 oxygen neighbors. Angular dependence of the EPR spectrum shows that the electronic ground state of Ce3+ is different in these two matrices. It is mainly composed of vertical bar M-J vertical bar = 5/2 state in LPS and vertical bar M-J vertical bar = 3/2 state in LSO. The temperature dependence of the linewidth shows a noticeably long spin lattice relaxation time, especially in LPS, which is the result of a stronger crystal field in LPS than in LSO. (c) 2005 Published by Elsevier Ltd.