Luminescence properties of Ag2S and Ag4S2 in zeolite A

Abstract

Silver sulfide particles of different size are synthesized in the cavities of zeolites A and ZK-4 by exposing the Ag⁺-exchanged dehydrated zeolites to H₂S. The two smallest stable particles synthesized by this method are the Ag₂S molecule and the Ag₄S₂ cluster. Both show photoluminescence in the visible region. The luminescence properties of the samples are studied as a function of temperature, of the silver sulfide content, and of the co-cations. By using the Ca²⁺-exchanged form of zeolite A it is possible to synthesize silver sulfide–zeolite systems which contain Ag₂S and Ag₄S₂ in the same zeolite crystal. After excitation with UV light energy transfer from the excited Ag₂S to Ag₄S₂ most probably occurs. These systems are potential materials for thermometry because their luminescence properties strongly depend on the temperature.