Luminescence and vibrational spectra of Ba5Li2W3O15

Abstract

The infrared and Raman spectra of Ba5Li2W3O15 are reported down to 200 cm−1. From the internal stretching modes of the tungstate octahedra the crystallographic order between lithium and tungsten in the face-sharing octahedra can be derived. The green tungstate luminescence shows a low quenching temperature that is described with the Dexter-Klick-Russell model. The U6+ ion shows a yellow emission in Ba5Li2W3O15. There is ample evidence for two different U6+ centers with different decay times (10 and 80 μsec) and different emission and excitation spectra. One of these is located in a single layer of tungstate octahedra, the other in a double layer of octahedra.