Possibility of RGB emission by Eu2+ ion doped MIIMIIIMVI phosphors for color inorganic electro- luminescent displays

Full text: Eu2+ ion give broad-band emission due to f-d transitions. The 5d orbital are not shelled from the host lattice by any occupied orbital. Therefore the wavelength positions of the emission bands depend on host and change from hear UV to red. With increasing crystal field strength, the emission bands shift to longer wavelength. The broad band absorption and luminescence of Eu2+ is parity-and spin-allowed and lifetime is sub-microseconds. In resent years, many efforts have been devoted to luminescence studies of thio gallates and thio-aluminates doped with rare-earth ions because of their chemical stability in ambient environments. In ternary compounds both the ligand field at the divalent cation site and the nephelauxetic effect are reduced by the presence of trivalent or tetravalent ions. This effect is more pronounced with Al than with Ga. In a same family of compounds, the emission band generally shifts to shorter wavelengths with increasing MII/MIV or MVI/MIII ratio. In this paper we revisited the luminescence of the phosphors CaGa2S4, BaGa2S4, BaAl2S4 activated by Eu2+ ion. Influence of temperature and Eu2+ concentration on the luminescence characteristics of these phosphors are studied. These dates will be useful to evaluate the quality oi the powder or thin films prepared for devices