title: Cathodoluminescence microanalysis of irradiated microcrystalline and nanocrystalline samarium doped BaFCl.
abstract: BaFCl:Sm3+ is an efficient photoluminescent storage phosphor for ionizing radiation. Cathodoluminescence (CL) microanalysis enables the Sm2+ and Sm3+ oxidation states of samarium doped BaFCl to be easily identified, provides information about electron-beam and X-ray induced modification of BaFCl:Sm, and enables the synthesis dependent spatial distribution of samarium dopants of <100 ppm concentration to be determined with sub-100 nm resolution at 295 K. CL spectroscopy of BaFCl:Sm particles reveals broad CL emissions at ≈ 360 and ≈500 nm associated with V k (Cl-) and oxygen-vacancy defects in the BaFCl host lattice and fine structure CL emissions associated with major 4GJ → 6HJ (Sm3+) and 5DJ → 7FJ (Sm2+) transitions. CL microanalysis shows samarium dopants are uniformly distributed in conventional sintered microcrystalline BaFCl:Sm. In contrast, CL investigations reveal that for BaFCl:Sm nanoparticles, which have been prepared using a co-precipitation method, with greatly improved Sm3+ → Sm2+ conversion efficiency, the samarium dopants are concentrated near the particle surface resulting in a BaFCl:Sm3+ shell surrounding the BaFCl core, which is stable to energetic irradiation.
authors.affiliation: School of Physics, University of New South Wales, Sydney NSW 2052, Australia. Marion.Stevens-Kalceff@unsw.edu.au
authors.forename: Marion A
authors.initials: MA
authors.lastname: Stevens-Kalceff
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Liu
authors.forename: Hans
authors.initials: H
authors.lastname: Riesen