Trivalent lanthanide ions (Ln3+) doped in hexagonal (β)-NaYF4 nanocrystals (Na24Y23Ln 1F96, Ln = La, Ce, Pr, Nd, Pm, Sm, Eu, Gd) were systematically studied by density functional theory (DFT) with a perturbative account for spin-orbit coupling. The simulated results, including the optimised molecular structures, electronic and magnetic properties, are compared to previous spin-polarised DFT studies in the same system. The spin-orbit coupling effects become significant with the increase in the number of unpaired 4f electrons in the doped lanthanide ions, particularly for the Sm3+-, Eu3+- and Gd3+-doped nanocrystals. Abnormal behaviour of Eu3+-doped nanocrystals was observed due to the Wybourne-Downer mechanism. A sandwich-like 2p-4f-4d,5d electronic structure for Na 24Y23Ln1F96 and the energies of the highest occupied 4f electrons from Ce3+ to Gd3+ are consistent with Dorenbos's relationship. The energy difference between the first and second Russell-Saunders terms (2S+1L) of the lanthanide dopant is consistent with Carnall's experimental results and with earlier spin-polarised DFT calculations.
Bibliographical noteFunding Information:
This research was supported by South Dakota Governor’s Office of Economic Development, NSF award EPS0903804, and by the DOE, BES – Chemical Sciences, NERSC Contract No. DE-AC02-05CH11231, allocation Award 85213, 86185, 86898 ‘Computational Modeling of Photo-catalysis and Photoinduced Charge Transfer Dynamics on Surfaces’. P.S. May and D.S. Kilin acknowledge support from NASA (Cooperative agreement number: NNX10AN34A). The USD High Performance Computing facilities operated by Douglas Jennewein are gratefully acknowledged.
- Dorenbos's relationship
- Russell-Saunders terms
- Spin-orbit coupling
- Wybourne-Downer mechanism