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Abstract:
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In this paper, materials of ZnS:Cu, ZnS:Mn and ZnO:Co were prepared by ceramic
method and co-precipitated method. The presence of transition metals such as Cu2+(3d9),
Mn2+(3d5) in ZnS and Co2+(3d7) in ZnO make blue bands at around 476 nm, 486 nm and green
band at around 514 nm disappeared. Simultaneously, there are luminescence bands at around 533
nm, 582 nm, 693 nm for bulk samples of ZnS:Cu, ZnS:Mn, ZnO:Co and 603 nm for
nanocrystalline sample of ZnS:Mn. These bands are characterized by Cu2+ ions, Mn2+ ions:
[4T1-6A1] and Co2+ ions: [4T1-4A2] in ZnS:Cu, ZnS:Mn and ZnO:Co, respectively. Time-resolved
luminescence spectra of these samples show that lifetime of electrons at excited states is 1.90 ms,
0.79 ms and 8.60μs corresponding to bulk sample ZnS:Mn, nanocrystalline sample ZnS:Mn and
bulk sample ZnS:Cu. The luminescence material of ZnS:Cu has been tested in off-set print for
anti-imitated stamps. |