Wydział Chemii

Mirosław Karbowiak

A. Mech

Janusz Drożdżyński

Norman M. Edelstein

2003

Physical Review B

67

195108/1-195108/17

10.1103/PhysRevB.67.195108

Naukowa

Angielski

Artykuł

Single crystals of (U4+,U3+):Ba2YCl7 were grown by the Bridgman-Stockbarger technique. The U4+ and U3+ ions substitute for Y3+ and have C1 site symmetry in Ba2YCl7. Sixty energy levels of U4+ were assigned to 40000cm−1 from absorption, excitation, and luminescence spectra, which encompasses all but the 1S0 multiplet. A crystal-field analysis was performed by fitting 8 atomic and 19 crystal-field parameters to the experimental Stark levels. The values obtained from the fit had a standard deviation of 36.6cm−1 and agreed with those calculated from the angular overlap model. Efficient luminescence was observed at 7 K from the4G7/2 and 4F9/2 levels of the U3+ ions and from the 1D2 and 1I6 of the U4+ ions with decay times of 0.5, 0.55, 9.2, and 4.3 μs, respectively. For the U4+ ions, a very strong anti-Stokes emission was observed due to energy-transfer processes. The emission of the U3+ ions is strongly quenched by temperature in contrast to that of the U4+ ions for which emission was observed even at room temperature. Energy transfer between the U3+ and U4+ ions has been shown to occur in the (U4+,U3+) doped Ba2YCl7.

https://doi.org/10.1103/PhysRevB.67.195108