Radiation-Induced Effects and Valence Changes of Samarium Ions in Sr[sub 3]Sm(PO[sub 4])[sub 3]

Abstract

Ternary orthophosphate [Sr3Sm(PO4)3] with a stoichiometric component of Sm3+ ion was prepared by a solid-state reaction. The phase formation of the sample was investigated by X-ray powder diffraction measurement. Samarium ions can be incorporated into two forms, divalent and trivalent. Exposure to X-ray irradiation can cause Sm3+→Sm2+ conversion in this host. The samples were investigated by photoluminescence and lifetime measurements. After excitation into the 4normalf55normald1 levels, the Sm2+ ions showed normalD50→normalF7J (J=0,1,2) emission together with the broad band of 5d→4f transition. The luminescence of Sm2+ ions was sensitive to the temperature. With increasing temperature, the luminescence intensity of 5d→4f emission band of Sm2+ ions appeared and got stronger. The stability of an Sm2+ ions created by X-ray irradiation was investigated by photobleaching under excitation at 488 nm of Ar+ laser. The defects created by X-ray irradiation were briefly discussed. These results would be helpful to understand the reduction mechanism of Sm2+ ion in the Sm3+ concentrated host.

The Irradiation Induced Valence Changes and the Luminescence Properties of Samarium Ions in Ba[sub 2]SiO[sub 4]

“…The similar broad emission bands after the X-ray irradiation were also reported in SrO-BaO-P 2 O 5 -B 2 O 3 glass, 40 KSrPO 4 ͑Ref. 41͒ and Sr 3 Sm͑PO 4 ͒ 3 crystals, 42 and sol-gel derived Al 2 O 3 -SiO 2 glasses, 43 which were assigned to the 5d-4f radiative transition of Sm 2+ .…”