EPR theoretical study of local molecular structure for tetrahedral Fe3+ centers in zinc oxide

A theoretical method for studying the inter-relation between electronic and molecular structure has been proposed by diagonalizing the complete energy matrices for a d5 configuration ion in a trigonal ligand field. As for ZnO:Fe3+system, the local lattice distortion for the tetrahedral Fe3+ centers in zinc oxide has been investigated by considering the second-order and fourth-order EPR parameters D and (a − F) simultaneously. The results indicate that the local lattice structure around tetrahedral Fe3+ centers exhibits a compression distortion, i.e., the (FeO4)5− entity in ZnO:Fe3+ system is smaller than the (ZnO)6− entity in ZnO crystal. The local lattice structure distortion parameters ΔR = −0.119 A and Δθ = 0.339° for Fe3+ ion in ZnO:Fe3+ system are determined. Furthermore, the displacements ΔZ1 = −0.050 A for transition-metal ion along the C3 axis, and ΔZ2 = −0.169 A for the distance variation between the O2− along the C3 axis and the lower oxygen plane are obtained.