OPTICAL STUDIES OF LAYERED INORGANIC SOLIDS: A NOVEL PHASE TRANSITION AND ENERGY TRANSFER STUDIES

The optical properties of a group of dicyanoargentates(1) and dicyanoau-rates(1) have been studied. The samples include K2Na[Ag(CN)2I3, Tb[Ag(CN)2]3, Tb[Au(CN)2I3 and a series of compounds of the form Tb,Lal-,[Ag(CN)2]3 with x=0.001, 0.01 and 0.1. Additionally, a novel type of silver-gold mixed- metal sample ( L ~ [ A ~ , A u ~-, ( C N) ~ ] ~ with x=0.9 and 0.5) was synthesized and characterized. The compound K2Na[Ag(CN)2I3 has earlier been shown to exhibit a phenomenon known as luminescence thermochromism, whereby only one emission band is present a t very low temperatures and very high temperatures, but a second, lower energy band is also present a t intermediate temperatures. This prompted further investigation to explain this behavior. This investigation revealed the existence of an interesting struc-tural change which is postulated to be an example of a novel type of phase transition, but did not explain the luminescence thermochromism. Further study, including lu-minescence lifetime results, was necessary to form a model involving energy transfer a t lower temperatures and back-energy transfer a t higher temperatures. These dicyanoaurates(1) and dicyanoargentates(1) were also studied in the contex