Comment on “the role of sulphur-oxyradicals in thermoluminescence and exoelectron emission of CaSO4 phosphors by R. Huzimura and K. Atarashi”

Thermoluminescence of thulium sensitized by terbium in β-phase Ca3(PO4)2

“…It is considered that by the existence of Tb3' ions, the emission efficiencies of the 345 nm (3P, + 3H,) and 355 nm (ID2 -+ 3H,) bands are increased and their emission efficiencies increase in proportion to the number of luminescence centers. The process leading to TL emission in the present samples may be a change of the valence state of Tm3+ ions to Tm2+ by trapping an electron under X-ray irradiation [9], and the holes freed simultaneously with the electrons might be trapped by the P-phase Ca,(PO,), lattice by forming colour centers or by making some radicals derived from (PO4),- [lo]. The increase of the number of luminescence centers due to the existence of Tb3' ions and the emission from the excited state of Tm3+ ions can be given schematically as follows:…”