Structural characterization and compositional dependence of the optical properties of Ge–Ga–La–S chalcohalide glass system

Abstract In this paper, chalcogenide glasses of 80GeS2 (20 x)Ga2S3 xLa2S3 (x = 0, 1, 3, 5 mol%) were synthesized through the traditional melt-quenching technique. The effects of La2S3 addition on the thermal, optical, and structural properties of Ge Ga S glasses were investigated. Results showed that the synthesized glasses possessed considerably high glass transition temperature, improved glass forming ability, high refractive index, and excellent infrared transmittance. A redshift at the visible absorbing cut-off edge lower than 500 nm was observed with increasing of La2S3 content. Direct and indirect optical band gap values were calculated. SEM result suggested that this glass system owned better glass forming ability and uniformity. Raman spectral analysis indicated that the introduction of La2S3 induced the dissociation of Ge Ge metal bonds and transformed the [S3Ge GeS3] structure to GeS4 tetrahedrons. Consequently, the connectivity between tetrahedrons of the vitreous network was enhanced. This work suggests that La2S3 modified Ge–Ga La S glass is a promising material for infrared optical research.