C. K. Duan | Searcharxiv

arXiv2010

Extraction of crystal-field parameters for lanthanide ions from quantum-chemical calculations

A simple method for constructing effective Hamiltonians for the 4fN and 4fN-15d energy levels of lanthanide ions in crystals from quantum-chemical calculations is presented. The method is demonstrated by deriving crystal-field and spin-orbit parameters for Ce3+ ions doped in LiYF4, Cs2NaYCl6, CaF2, KY3F10 and YAG host crystals from quantum chemical calculations based on the DV-Xα method. Good agreement between calculated and fitted values of the crystal-field parameters is obtained. The method can be used to calculate parameters even for low-symmetry sites where there are more parameters than energy levels.

cond-mat.mtrl-sci↗

arXiv2005

The unusual temperature dependence of the Eu$^{2+}$ fluorescence lifetime in CaF$_2$ crystals

Fluorescence lifetimes of Eu$^{2+}$ doped in CaF$_2$ are measured at various temperatures between 4K and 450K. The lifetime increases with between 100K and 300K, in contrast to the usual lifetime-temperature dependence. At higher or lower temperatures the lifetime decreases with increasing temperature. The phenomenon is explained by simulation of the energy levels and lifetimes of low-lying $4f^65d$ states involved in the fluorescence.

cond-mat.mtrl-sci↗