Review of Cholorosilicates as Phosphor Hosts

Abstract Silicates and halides have been known to be good luminescent materials for long. These two types of hosts have some positive aspects and certain drawbacks, for example, though silicates are stable, they require relatively higher synthesis temperatures. Halide lattices are better suited for several applications like optically stimulated luminescence, thermoluminescence, scintillation, etc. and defects/color center/exciton formation is important. Halides have lower melting points as well. On the other hand, except for fluorides, other halides are quite hygroscopic. Stability in the ambient can pose some problems in applications and some measures for protection have to be taken. To enjoy the benefits of both silicates and halides, chlorosilicate lattices can be suitable. Chlorosilicates can be synthesized at significantly lower temperatures as compared to silicates. They are also less hygroscopic than the constituent chlorides. Research work on chlorosilicates is not as extensive as that on silicates and halides. These are promising luminescent materials whose potential remains still unexploited. A review of various chlorosilicate phases, i.e., of the studies on synthesis, crystal structures, luminescence etc. already carried out, is presented here with the objective of providing impetus to research work on chlorosilicates.