STUDY OF THE OPTICAL-PROPERTIES OF EU3-DOPED ZNS NANOCRYSTALS()

Absorption and photoluminescence excitation spectra are presented for ZnS:Eu nanocrystals. The average size of the ZnS:Eu nanocrystals was a bout 3.6 nm deduced from the absorption spectra and was independent of the doping concentration of Eu3+. The characteristic luminescence fro m the D-5(0)-F-7(J) (J=0, 1, 2) transition of Eu3+ was observed. This is attributed to the electrons and holes being localized around Eu3+, and the possibility of energy transfer from band to band excitation in ZnS to trivalent rare earth Eu3+ is increased. The location of Eu3+ i s different for different doping concentrations deduced from the relat ive luminescence intensity. Three main types of Eu3+ ion exist in the colloid. The samples undergo growth and aging processes according to t he variation of the luminescence intensity after preparation. A tentat ive explanation is given that the location of the Eu3+ ions and the su rface states may play important roles. (C) 1998 Elsevier Science S.A.