Study of local structures and optical spectra for octahedral Fe3+ centers in a series of garnet crystals A3B2C3O12 (A = Cd, Ca; B = Al, Ga, Sc, In; C = Ge, Si)

Using the unified ligand-field coupling scheme, the local structures and optical spectra of octahedral Fe3+ centers in a series of garnet crystals have been investigated systematically with two different values of parameter A4. Our results show that the local structures of octahedral Fe3+ centers in doped systems are similar to one another if there are the same external environments around B ions in the host crystals. Being independent of the sign of the spin Hamiltonian parameter b 2 0 , it is increasingly close to zero along with structure parameter R increasing. Moreover, b 2 0 is almost linear with the change of structure parameter θ.