Luminescence of ZnS:Dy,Cu,ZnS:Pr,Cu and ZnS:Ho,Cu phosphors depending on the activator and coactivator concentration

摘要: The study of rare-earth activated ZnS phosphors is considerable interest in view the theoretical interpretation lanthanide (Ln) ion spectra crystals as well connection with possible application these luminescent materials practice, especially electroluminescent devices. In many papers are studied where only Ln ions incorporated activators. some (e.g. [1-6]) Li + , Cu or F also introduced charge-compensating coactivators. However, sufficiently complete information, particularly about influence activator and coactivator concentrations on properties, under same conditions phosphor preparation, has not yet been obtained. This letter deals dependence photoand electroluminescence intensity spectrum doped dysprosium, praseodymium holmium coactivated copper concentrations. Results for other rare earth will be reported elsewhere. All samples were obtained by firing polycrystalline Ln(NO3)3 CuSO4 added at 1100 ° C 1 h an H2S flow. luminescent-grade used was precipitated HzS from a purified ZnSO4 solution deoxidated heating 500°C before introduction coactivator. absence changes emission photoexcited : Dy increasing concentration given Table I Fig. l a. Spectral measurements higher resolution show that broad band appears 515 nm addition to lines due f-f transitions (Fig. lb). A similar spectral position ascribed oxygen-containing dysprosium centres [7], whereas [1] broadband 440 445nm observed radiative electron DyznVzn associates assumed. When amount raised 8 x 10 2mo1% became strongly predominant: 486 573 line groups superimposed them low around 668 753 vanished la, curve 2). Introduction 2 led enhancement photoluminescence efficiency more than order magnitude (Table I); this probably -* energy transfer [3] decrease Vzn result charge compensation through cuprous ions. Supposing first quantum yield f Dyzn-V(,'. compared Dyz. Dyz,-Cuzn, secondly created donor-acceptor Dyzn-Vzn associates, one may explain increase established strong relative rise concentration, Ccu. diminution luminescence Ccu > .-2 4 10-2mol % I) could caused quenching interaction between strongest registered presence n d t o 10-2mo1% dysprosium. effect seen la (curves 3 4); lb clearly appearance new 482 well-expressed intensities lines: long-wave shift group occurs redistribution do disappear even high CDy when present.