title: Effects of postannealing on the photoluminescence properties of coprecipitated nanocrystalline BaFCl:Sm3+.
abstract: Nanocrystalline BaFCl:Sm(3+), as prepared by coprecipitation from aqueous solutions, is an efficient photoluminescent X-ray storage phosphor. In the present study, we report effects on its photoluminescence properties resulting from postannealing treatment in air in the temperature range between 100 to 900 °C. Interestingly, upon annealing at temperatures from 200 to 600 °C in air, a small fraction of the Sm(3+) ions in nanocrystalline BaFCl can be reduced to Sm(2+) ions. In addition to the creation of Sm(2+) ions, two different sites of Sm(3+) ions, denoted as sites A and B, are observed when the nanocrystalline BaFCl:Sm(3+) is annealed between 500 to 900 °C. The temperature dependence of photoluminescence properties of the two different sites in the 500 °C annealed sample reveals that the Sm(3+) ions at site A are possibly located at or near the crystallite surface, whereas site B is situated in a very ordered environment. To the best of our knowledge, this is the first report on the reduction of Sm(3+) ions doped in alkaline-earth fluorohalides to Sm(2+) ions by annealing in air.
authors: School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, UNSW Canberra (ADFA), Canberra, ACT 2600, Australia.
authors: Zhiqiang
authors: Z
authors: Liu
authors: Marion A
authors: MA
authors: Stevens-Kalceff
authors: Hans
authors: H
authors: Riesen