CHARGE-TRANSFER TRANSITIONS OF 4D-TRANSITION AND 5D-TRANSITION ELEMENTS IN GARNETS

Electronic state calculations of the (M4+O62-)(8-) octahedral cluster (M = 4d- and 5d-transition elements) were performed by an unrestricted SCF SW-X alpha method. In order to verify the calculations, single cr ystalline films of (Gd,Ca2+)(3)(Ga,M4+)(5)O-12 were prepared by a liqu id-phase epitaxy (LPE) method onto (1 1 1)-oriented Gd3Ga5O12 (GGG) su bstrates, and their optical absorption spectra were measured in the ra nge 0.2-0.9 mu m. The absorption spectra are assigned to the charge-tr ansfer transitions from O2- 2p to M4+ d-orbitals or t(1u)(2p)-->t(2g) (d) and t(2u)(2p)-->t(2g)(d) transitions. (C) 1998 Elsevier Science B .V. All rights reserved.