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.

On the origins of the green luminescence in the “zero-dimensional perovskite” Cs4PbBr6: conclusive results from cathodoluminescence imaging

“…The present article also strongly corroborates the power of cathodoluminescence imaging for the elucidation of the nature of luminescent nanostructures. 40 In particular, CL imaging and spectroscopy appear to be a very powerful tool to analyse the spatial distribution and correlation of luminescence in lead halide nanosystems.…”

Nanotubes from the Misfit Layered Compound (SmS)1.19TaS2: Atomic Structure, Charge Transfer, and Electrical Properties

“…The CL spectra revealed f – f luminescence with a peak at 695 nm (see Figure S14), which was absent in the background. The 695 nm luminescence peak has been previously assigned to Sm 2+ and is attributed to the local reduction of Sm 3+ by the electron beam …”

“…The 695 nm luminescence peak has been previously assigned to Sm 2+ and is attributed to the local reduction of Sm 3+ by the electron beam. 80 …”

Effects of Postannealing on the Photoluminescence Properties of Coprecipitated Nanocrystalline BaFCl:Sm3+

“…It follows that, at higher temperatures, the Sm 3+ ions in site A are subject to significantly stronger electron–phonon coupling, which is frozen out at 2 K, than the ions in site B. Our previous photoluminescence spectroscopy and cathodoluminescence microanalysis investigations , indicated that the Sm 3+ ions at site A are located at or near the crystallite surface; the electron–phonon coupling is therefore governed by the interactions between the f-electrons and pronounced surface modes. In contrast, the emission line at 605 nm from Sm 3+ ions in site B is much less dependent on the temperature, which may indicate that the ions are more embedded within the host lattice; this observation may also indicate that there is a mismatch of lattice modes and the local vibrational modes of the Sm 3+ ion, i.e., a different coordination environment that does not allow coupling to lattice or surface modes.…”