Phase transition and elastic and optical properties of Lu2SiO5

Cerium-doped lutetium silicate (LSO:Ce) crystal is a well-known scintillator. However, there are two different structures reported for LSO crystal at ambient conditions in experiments. The structural, elastic, electronic and optical properties of the C2/c and P2(1)/c phases of LSO crystal have been investigated using first-principles method. The C2/c phase is found to be stable at ambient conditions. The phase transition from C2/c phase to P2(1)/c phase is predicted to occur at 6.3 GPa, together with a volume contraction of 3.7%. The bulk modulus of the C2/c phase is larger than the P2(1)/c phase. The hybridization of O-2p and Si-3p is found in the upper valence band of LSO crystal. The C2/c and P2(1)/c phases are predicted to be insulators with calculated gaps of 4.67 and 4.80 eV, respectively. The refractive index of LSO crystal is found to be about 1.9 for both phases. (C) 2013 Elsevier B.V. All rights reserved.