Phase transition and elastic and optical properties of Lu2SiO5

Abstract 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 C 2/c and P 2 1 /c phases of LSO crystal have been investigated using first-principles method. The C 2/c phase is found to be stable at ambient conditions. The phase transition from C 2/c phase to P 2 1 /c phase is predicted to occur at 6.3 GPa, together with a volume contraction of 3.7%. The bulk modulus of the C 2/c phase is larger than the P 2 1 /c phase. The hybridization of O-2p and Si-3p is found in the upper valence band of LSO crystal. The C 2/c and P 2 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.