... of the ZnS samples at x = 0, 0.25, 0.5, 0.75, and 1 were measured, and the energy gap was calculated from Tauc plots. A clear gradient in E_g was observed from 3.95 eV for the pure ZnS sample to 3.11 eV at x = 0.25, with an average value for the Bi-rich sample, BiS, of 3.59 eV...

... reserved 2020 energy gap optical properties refractive index B Tauc’s constant, a characteristic parameter of the material independent of the photon energy d_X-ray average crystallite size estimated from X-ray diffraction (XRD) analysis...