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When co-doped with La3+, Ba3(PO4)2:Eu2+ shows an intense thermally stimulated luminescence after X-ray irradiation. The phosphor is also optically stimulable. The stimulated emission is due to the Eu2+ ion. In the absence of Eu2+ a broad emission band is observed which is tentatively ascribed to a phosphate group close to the La3+ ion. EPR reveals the presence of H0 after irradiation. It is concluded that the substitution of La3+ on a Ba2+ site is accompanied by the introduction of H+ into the lattice. The latter ion acts as an electron trap; detrapping yields the stimulated luminescence.

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