The compound Na3SO4Cl X (X = Ce(3+), Eu(3+) or Dy(3+)) prepared by the wet chemical method was studied for its photoluminescence (PL) and energy transfer characteristics. The PL from Na3 SO4 Cl:Ce(3+) shows strong emission at 322 nm at an excitation of 272 nm. Therefore, an efficient Ce(3+) → Dy(3+), Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer had taken place in this host. The Dy(3+) emission caused by Ce(3+) → Dy(3+) energy transfer under ultraviolet (UV) wavelengths peaked at around 477 nm and 572 nm due to (4) F9/2 → (6) H15/2 and (6) H13/2 transitions with yellow-orange emission in the Na3 SO4 Cl lattice. An intense Dy(3+) emission was observed at 482 and 576 nm caused by the Eu(2+) → Dy(3+) energy transfer process and due to (4) F9/2 → (6) H15/2 and (4) F9/2 → (6) H13/2 transitions respectively. The Eu(3+) blue to red light emission caused by the Eu(2+) → Eu(3+) energy transfer peaked at 593 nm and 617 nm due to (5) D0 → (5) D3 transitions. The presence of trivalent Eu in Na3 SO4 Cl suggested the presence of Eu(3+) in the host compound that occupied two different lattice sites and that peaked at 593 and 617 nm due to (5) D0 → (7) F1 and (5) D0 → (7) F2 transitions respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems due to its non-degenerate emitting (5) D0 state. The present paper discusses the photoluminescence characteristics of Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer. This compound may be useful as a lamp phosphor.

Mn phosphors were studied for 5 Gy γ -ray dose. In TL glow curve, two peaks have been observed at 129 • C and 224 • C for different concentrations of Ce and Dy, whereas Mn peaks at 212 • C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248 • C). A significant single peak is observed in the case of Na 3 SO 4 Cl:Mn and Na 3 SO 4 Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h −1 for 5 Gy γ -rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO 4 : Dy for the same γ -rays dose. The paper discuses the preliminary TL characteristics and effect of γ -rays

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