Theoretical calculation for the multiplet structure of the tetrahedrally coordinated Cr4+ in Y3Al5O12

Abstract

The multiplet structure of the tetrahedrally coordinated Cr 4ϩ in Y 3 Al 5 O 12 ͓yttrium aluminum garnet ͑YAG͔͒ was calculated by the ab initio electronic-structure calculation method. The authors examined the dependence of the multiplet structures on the size of cluster models, with the use of (CrO 4 ) 4Ϫ ͑without point charges͒, (CrO 4 ) 4Ϫ ͑with point charges͒, (CrY 6 Al 4 O 44 ) 54Ϫ , and (CrY 18 Al 42 O 148 ) 112Ϫ models. The covalency of the impurity-level molecular orbitals was analyzed, and it was revealed that the wave functions of the atoms outside the CrO 4 tetrahedron should not be neglected. The validity of the assignment of the peaks in the absorption spectrum written in the literature was evaluated by the calculated magnitude of the spin-orbit splittings and the oscillator strengths of the transitions, which were obtained by the fully relativistic many-electron calculation. The effect of the codopant on the transition probability was also estimated by (CrCaY 5 Al 4 O 44 ) 55Ϫ models. It was indicated that the nearest Cr-Ca pairs would reduce the symmetry, and could produce some satellite peaks. The mixing of the wave functions of the triplet states was numerically analyzed, and the results were correlated with the transition probability. The traditional nephelauxetic parameter was estimated, and the value 0.51 was obtained. It was confirmed from first principles that the magnitude of the nephelauxetic parameter in some literature was appropriate.

Calculation of X-ray absorption near edge structure of CeO2 using a model cluster

“…Ogasawara and co-workers independently developed the relativistic DV-Xa method. On the basis of this approach, they calculated the multiplet structure of transition-metal L II III edge and achieved an excellent agreement with the experiments [21][22][23][24][25][26].…”

First-principles analysis method for the f–d transitions of heavy metal ions

“…The details of the present method were written in the applications to the analyses of the X-ray absorption near-edge structures in oxide compounds [6], and the 3d-3d transitions in solid-state laser materials [7,8].…”

First principles analysis of the MgAl2O4:Ni2+ absorption spectrum

“…To emphasize the wide applicability of the method employed in the present paper, we mention that it has been successfully applied to the analysis of the Cr 4+ absorption spectrum in Y 3 Al 5 O 12 [11] and silicate crystals [12], 4f-4f absorption spectrum of LiYF 4 :Dy 3+ [13], 4f-5d absorption spectra of various trivalent lanthanides in LiYF 4 [14,15], high lying 4f and 5d energy states of free trivalent lanthanides [16,17], calculations of the X-ray absorption near edge structure (XANES) spectra of transition metal ions [18][19][20].…”