Raman scattering and electroluminescence of ZnS:Cu,Cl phosphor powder

Abstract

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.

Synthesis and characterization of Zn1−xCdxS:Cu, Cl red electroluminescent phosphor powders

“…(1) found in samples A and B was proposed to result from the tensile strain (ε > 0) induced by the interstitial incorporation of Cu ions in the lattice [11]. Therefore, Zn 1−x Cd x S alloys with a specific x can be prepared successfully using this method due to the better atomic diffusion between ZnS and CdS during the solid state reaction at higher temperatures as compared to the chemical methods such as coprecipitation, which suffers from the problem of the different solubility-product constants (K sp ) of CdS (10 −27 ) and ZnS (2 × 10 −25 ) [12].…”

Luminescence of ZnS:Cu,Cl Phosphor Powder Excited by Photons, an Electric Field and Cathode Rays

“…2, the average size of the phosphor powder was approximately 5µm, indicating that the whole powder particle can be excited by photons with a wavelength of 343nm. However, according to the bipolar field emission model proposed by Fischer [16] and our previous studies [7][8][9], conductive Cu x S precipitates are necessary for luminescent ZnS particles to intensify the electric field and to allow tunneling electrons to recombine with radiation in luminescent centers. This is shown per the dependence of emission intensity on the electric field shown in Fig.…”

“…[18] Moreover, the solubility of Cu in ZnS was limited to a constant value, which was less than 400ppm (indicated by the dashed line in Fig. 2) [7][8][9]. Therefore, the Cu near the powder surface beyond the solubility limit was supposed to enter the lattice interstitially (Cu i ), and some will precipitate as Cu x S for the EL.…”

The pronounced role of impurity phases in the optical properties of Mn catalyzed ZnS nanostructures

“…Excess incorporation of Cu in ZnS has been reported to shift the Raman longitudinal optical (LO) phonon modes. 26 In this case, Cu was incorporated interstitially in the ZnS lattice and induced the tensile stress and structural transformation. 26 Zhang et al, reported a new line at 338 cm −1 identified as the surface optical (SO) phonon mode in ZnS nanowires, which was confirmed by using the dielectric continuum model.…”

“…26 In this case, Cu was incorporated interstitially in the ZnS lattice and induced the tensile stress and structural transformation. 26 Zhang et al, reported a new line at 338 cm −1 identified as the surface optical (SO) phonon mode in ZnS nanowires, which was confirmed by using the dielectric continuum model. 27 Self-doping of different catalysts (Au, Sn and Mn) in VLS grown ZnS nanostructures have also resulted in a systematic shift in the LO and surface optical (SO) phonon modes.…”