Compositional dependence of refractive index and oscillator parameters in TlGaS2xSe2(1−x) layered mixed crystals (0 ≤ x ≤ 1)

Optical characterization of TlGaS2xSe2(1−x) mixed crystals have been carried out at room temperature using the transmission and reflection measurements in the wavelength range of 400–1100 nm. The spectral dependence of the refractive index for all compositions of studied crystals were obtained. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single-effective-oscillator model. The compositional dependencies of refractive index dispersion parameters: oscillator energy, dispersion energy and zero-frequency refractive index were revealed.