We calculate the crystal-field energy levels for Fe3+, Fe4+, and Fe2+ ions in BaTiO3 by diagonalizing the complete matrices for the electrostatic term, the Trees correction, and the crystal-field interaction. We use the superposition model to determine the crystal-field parameters for Fe3+, Fe4+, and Fe2+ ions in each of the three phases, i.e., cubic, tetragonal, and orthorhombic, of BaTiO3. We use a recently developed computer package to diagonalize the full Hamiltonian within the whole configuration 3d4(Fe4+), 3d5(Fe3+), and 3d6(Fe2+). The absorption spectra and the charge-transfer process of deep Fe centers in BaTiO3 are investigated, and possible mechanisms for the photorefractive effects in BaTiO3 are discussed.
© 1995 Optical Society of America
Y. M. Chang, H. F. Wang, and C. Rudowicz, "Crystal-field energy levels for deep Fe centers at orthorhombic and higher symmetry sites in BaTiO3," J. Opt. Soc. Am. B 12, 544-552 (1995)