| Several phosphors of importance for alternating-current thin-film electroluminescent (ACTFEL) device applications have been synthesized and studied. Particular attention was paid to synthesis of a bright and efficient green ACTFEL phosphor by using codopants, solid-solution, and ceramic processing techniques.; Emission from SrS:Cu has been studied. The specific emission color depends strongly on the local environment surrounding the Cu+ ion in the SrS lattice. Both blue and green emissions have been reported previously, and there remains considerable debate as to the origins of these emissions. A new model emphasizing the structural environment of the Cu atom in its ground state is used to account for new and previously reported data on the SrS:Cu system. The model is described, extended to emission colors in other Cu-doped alkaline-earth sulfides, and used to account for the performance characteristics of EL devices.; The differences in ACTFEL performance of ZnS and SrS were studied by comparing the EL emission spectra of each with a series of lanthanide dopants. On the basis of these spectra and the electrical characteristics of the device, it was confirmed that the electron distribution for ZnS is not hot enough at higher energies to efficiently excite luminescent impurities in the blue region of the spectrum and this results in inefficient blue EL emission as compared to SrS.; Hydrothermal dehydration, a simple method for preparing refractory silicates at low temperatures and pressures, is introduced. The method involves precipitation of a hydroxylated silicate, followed by dehydration under equilibrium conditions. Three silicates were synthesized using this method: Zn2SiO 4, SnSiO3, and Mg2SiO4. |
