Towards a new group of olivine-type afterglow phosphors: the case of Ca_2GeO_4:Dy~(3+)

摘要

Powder XRD confirms that Ca2-3xDy2xGeO4 (x = 0.00, 0.01, 0.025, 0.04) synthesized by ceramic route crystallize with the olivine-type unit cell (space group Pnma, Z = 4). The trivalent dysprosium ions occupy two crystallographically nonequivalent sites (4a) and (4c) with the C-i and C-s symmetry, respectively. Raman spectroscopy corroborates the crystal structure features of orthorhombic Dy3+-doped Ca2GeO4 with the maximum phonon energy of 760 cm(-1). The phosphors with optimal dopant concentration of 1 at% exhibit yellow emission under 349 nm excitation and white afterglow for more than 1 h after 240 nm excitation for 5 min. (C) 2018 Elsevier B.V. All rights reserved.