Abstract: The mechanisms for the optically and thermally stimulated luminescence of BaFCl_tTb crystal are proposed. As being X-irradiated the doped trivalent terbium ion may trap a hole and be oxidized to the tetravalent state. Meanwhile the existing chloride vacancy V(Cl) in the crystal may trap an electron and is converted into a F-center. In the processes of optically and thermally stimulated luminescence the tetravalent terbium ion may capture an electron ionized from the F-(tenter and then may be reduced to the excited state of Tb³⁺, from which the characteristic emission of Tb^{3+ 5}D₄^-7F, transition takes place.

Key words: Thermoluminescence, Photostimulated luminescence, Terbium, Barium fluochloride