title: EPR, ENDOR and HYSCORE study of X-ray induced centres in K2YF5 thermoluminescent phosphors.
abstract: X-Ray irradiation at room temperature produces several paramagnetic centres in rare-earth activated K2YF5 crystals, whose thermal annealing behaviour can be linked with the occurrence of thermoluminescence (TL) glow peaks. In this paper, continuous wave (CW) and pulsed paramagnetic resonance techniques are used to study the structure of a very stable radiation-induced centre, which may be involved in the TL peak at approximately 390 degrees C reported for Ce- and Tb-activated crystals. From the spectra the centre's g tensor and hyperfine (nuclear quadrupole) tensors for several 19F and 39K neighbouring nuclei are extracted, but no self-hyperfine interaction could be detected. Based on the analysis of the interaction tensors, a model is constructed consisting of an oxygen-related radical (e.g. O(-) or O2(-)) on a substitutional F(-) position in the mirror plane of the YF7 polyhedra. Such a centre most probably corresponds to a trapped-hole state.
authors: Ghent University, Dept. of Solid State Sciences, Krijgslaan 281-S1, B-9000, Ghent, Belgium.
authors: Dmitry
authors: D
authors: Zverev
authors: Henk
authors: H
authors: Vrielinck
authors: Freddy
authors: F
authors: Callens
authors: Paul
authors: P
authors: Matthys
authors: Sabine
authors: S
authors: Van Doorslaer
authors: Nicholas M
authors: NM
authors: Khaidukov
mesh_terms: D002627:Chemistry, Physical / Q000379:methods; D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005459:Fluorides / Q000737:chemistry; D007726:Krypton / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D017382:Reactive Oxygen Species; D013696:Temperature; D014965:X-Rays; D015019:Yttrium / Q000737:chemistry*
chemical_list: D017382:Reactive Oxygen Species; D015019:Yttrium; D007726:Krypton; D005459:Fluorides; D011188:Potassium