Different phosphors used in CRO screens:

 Phosphors:


    The luminescent crystal which exhibits phosphorescence are called phosphors. There are different kinds of luminescent crystals which exhibit the phosphorescence.

  •     Zns and CdS activated with Cu, Mn, Ag, Au etc.,

  •     Alkali halides activated with thalium.

  •     Compounds with luminescence in the pure form such as gadolinium sulphate, manganous halides, molybdates etc.,
  •     Oxide phosphors such as self activated ZnO and  activated with transition metals.
  •     Silicate phosphors such as Zinc ortho silicate activated with divalent manganese.
  •     Organic crystals such as anthrascence activated with naphthalene.

Among these various phosphors, the phosphors used for CRO screens are

  •     Zinc-ortho silicate for green will be used in CRO tubes for general purpose.
  •     Calcium-tungstate for blue will be used in CRO tubes for fast photography.
  •     Zinc-cadmium sulphate for white will be used TV receiver tubes.
  •     Zinc-sulphate activated with Ag is used in colour television for Blue colour.
  •     Zinc-cadmium sulphide activated with copper is used in colour television for green colour.
  •     Yttrium oxysulphide activated with Europium and terbium is used in colour televisions for red colour.


Applications of phosphors:

  •     Fluorescent.
  •     Cathode ray oscilloscope.
  •     Television
  •     Radar
  •     Nuclear and radiation detectors
  •     Scintillation counters.

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