LUMINESCENT PROPERTIES OF CAS-CD PHOSPHORS

Fluorescence emission and excitation spectra in Ca(1-x)Cd(x)S have been investigated with the aim of elucidating the electronic processes determining the previously observed strongly enhanced ultraviolet emission levels for x < 0.04. In fluorescence emission studies at 77 K, the optimum excitation wavelength for ultraviolet emission at 370 nm was observed to shift from 270 to 300 nm as x increased to 0.035, whilst the blue-green emission at 485 nm was largely suppressed with increasing x. At 295 K, the fluorescence emission at 380 nm shifted to 405 nm and that at 485 nm to 450 nm as x increased from 0.00016 to 0.035. The role of cadmium on cationic lattice sites and its relationship with adjacent anionic sites is discussed.