Lead emission from the cadmium Suzuki phase in NaCl:CdCl2:Pb2+

Abstract

The system NaCl:CdCl2:Pb2+ has been studied by the photoluminescence technique. The results for quenched crystals consist of the usual emission bands of Pb2+ in a NaCl matrix: at room temperature, one intense band centred at 314 nm; at liquid-nitrogen temperature, two bands, one peaking at 312 nm and one weak band at 380 nm. The aging of these crystals at 355 K produces a cadmium Suzuki phase precipitate in which the minor impurity Pb2+ ions are incorporated. The emission of these incorporated lead ions into the Suzuki phase consist of two emission bands. These are centred at 388 and 460 nm; the latter is very intense even at room temperature. The temperature behaviour of these bands suggests that the former can be assigned to the AX band, while the latter to the AT emission band. This might be the result of a large coupling to the T2g vibrational modes of the Cd2+ Suzuki phase. In crystals annealed at higher temperatures the cadmium ions precipitate into the CdCl2 phase. For this case the lead emission consists of the usual high-energy AT band (390 nm) and the low-energy AX band (458 nm).