Calculation of the electronic structure of AmO₂ and Pr₆O₁₁ for XANES analysis with redox property

Abstract

ABSTRACT:We calculated X-ray absorption near-edge structure (XANES) of Am L III of AmO 2 and Pr L III of Pr 6 O 11 using the relativistic discrete-variational (DV)-X␣ method based on the Dirac-Slater method, and compared it with the experimental spectra. These spectra were calculated on a model of ). In spite of using small cluster models, the calculated spectra were in good agreement with the experiment ones. Besides, we calculated the electronic structure of AmO 2 and Pr 6 O 11 to analyze the peak structures of XANES. From this calculation, it was found that O s, p, and f components had influence on the specific peak structures but that O d component had influence on various peak structures for AmO 2 and Pr 6 O 11 . From this result, it was suggested that the change of the electronic structure of actinide 6d and O d or f was important for actinide L III XANES corresponding to oxygen to metal ratio in the oxide nuclear fuel. On the basis of these results, we calculated the fine structures of densities of states and the transition energy from the HOMO to the white line of AmO 2 , UO 2 , and Pr 6 O 11 and investigated redox properties of Am and U in the oxide nuclear fuel with the evaluation of validity of Pr as simulant materials of Am.

XPS Study of Ion Irradiated and Unirradiated UO2 Thin Films

“…Adsorption energies of water on differently oriented uranium dioxide planes were calculated. 14, 15,16 The work on the study of the electronic structure of uranium and its alloys [17][18][19][20][21] and oxides UO 2+x (x≤0 and x≥0) employed theoretical calculation results, [22][23][24][25][26][27][28][29][30][31][32][33][34] photoelectron spectroscopy (PES) [35][36][37][38][39][40][41] and X-ray photoelectron spectroscopy (XPS) widely. 38,[42][43][44][45][46][47][48][49][50][51][52][53][54][55] These techniques were used to study films on various substrates.…”

“…The work on the study of the electronic structure of uranium and its alloys − and oxides UO 2+ x ( x ≤ 0 and x ≥ 0) employed theoretical calculation results, − photoelectron spectroscopy (PES), − and X-ray photoelectron spectroscopy (XPS) widely. ,− These techniques were used to study films on various substrates. − ,− …”

X-ray photoelectron spectra structure and chemical bonding in AmO2

“…The ex per i men tal [2][3][4][5][6][7][8][9][10][11][12] and the o ret i cal [13][14][15][16][17] studies of me tal lic am er i cium and Pu-Am al loys [11] have been con ducted. Also the ex per i men tal [1,2,8,[18][19][20][21][22][23][24][25] and the o ret i cal [21,[26][27][28][29][30][31][32][33][34] data on the elec tronic structure of am er i cium ox ides have been ob tained. The X-ray ab sorp tion near-edge spec tros copy (XANES) and ex tended X-ray ab sorp tion fine struc ture spec troscopy (EXAFS) struc tures of Am 2 O 3 and AmO 2 [20,23,28,31] and am er i cium-con tain ing com plex ox ides [1,18,21,24,25,35] have also b...…”

“…Also the ex per i men tal [1,2,8,[18][19][20][21][22][23][24][25] and the o ret i cal [21,[26][27][28][29][30][31][32][33][34] data on the elec tronic structure of am er i cium ox ides have been ob tained. The X-ray ab sorp tion near-edge spec tros copy (XANES) and ex tended X-ray ab sorp tion fine struc ture spec troscopy (EXAFS) struc tures of Am 2 O 3 and AmO 2 [20,23,28,31] and am er i cium-con tain ing com plex ox ides [1,18,21,24,25,35] have also been stud ied. The XPS spec tra of Am(NO 3 ) 3 ´ nH 2 O [36], as well as the elec -tron en ergy loss spec tros copy (EELS) of Am at the Am (O 4,5 ) [12] and Am (N 4,5 ) [10,37] ab sorp tion edges were mea sured.…”

“…It al lowed only a qual ita tive in ter pre ta tion of the low BE XPS from AmO 2 . Un for tu nately, the cal cu la tion re sults for AmO 2 [27][28][29][30][31][32][33] for the BE range 0-~15 eV did not take into account the over lap ping of the in ner va lence Am 6p and the O 2s atomic orbitals and, there fore, did not al low a cor rect va lence (~15 eV-~35 eV) XPS struc ture in terpre ta tion.…”