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Raman spectra of ZnS:Cu,Cl powders show a structural transition from hexagonal to cubic and a crystal growth with increasing Cu addition (>400ppm), which is supposed to result from Cu incorporation or CuxS precipitation. The redshift of longitudinal optical mode in ZnS:Cu,Cl with increased amounts of Cu suggests that the excess Cu ions were located interstitially in the lattice and created a tensile strain. Under an electric field (3.75×106V∕m), a broad emission spectrum superposing of green, self-activated blue, and blue bands can be observed in the powders (Cu⩾400ppm), which agrees with the luminescence centers of CuZn+, vacancies, and Cui+, respectively.

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The luminescent properties of the Ce3+ or Dy3+ singly doped and Ce3+/Dy3+ codoped in Ca3Y2Si3O12 novel phosphors were investigated, which are prepared by a sol-gel method. Ce3+ doped phosphor showed a brighter and broader violet-blue color emission band with a maximum peak centered at 389 nm, which is attributed to the parity and spin allowed 5d–4f transition. Photoluminescence spectra reveals that the white color emission is originated from the mixtures of two characteristic emission bands of Dy3+ ion, viz., the 473 nm blue emission (F49/2-H615/2) and the 580 nm yellow emission (F49/2-H613/2). codoping of Ce3+ has enhanced the luminescence of Dy3+ quite significantly upon the UV excitation wavelength (242 nm) and the optimized codopant concentration of Ce3+ is found to be 3 mol %. The mechanism involved in the energy transfer between Ce3+ and Dy3+ has been elucidated by an energy level diagram. The structure and morphology of the prepared samples have been analyzed by x-ray diffraction and transmission electron microscope.

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