Structural analysis of Tm3+ doped As–S–Ga glasses by Raman and EXAFS spectroscopy

Abstract

Structural properties of Tm 3+ doped AsS -Ga glasses were investigated using Raman spectroscopy and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at As Kedge, Ga K-edge and Tm L 3-edge. The Raman spectra are interpreted on the basis of comparison with the well-known Raman spectra of As 2 S 3 glasses the structure of which mainly consists of pyramidal [AsS 3/2 ] units interconnected by S-S chains. Incorporation of Ga 2 S 3 in As 2 S 3 glass matrix induced the dissociation of S-S chains in behalf of the formation of tetrahedra [GaS 4 ]. Moreover, introduction of Tm into AsS -Ga glasses forms Tm-S bonds through the further dissociation of [AsS 3/2 ] pyramidal units. The deficiency of S in the glasses is compensated with the formation of As 4 S 4 structural units. The EXAFS results indicate that GaS bond distance in the tetrahedra [GaS 4 ] decreases from 2.29Å to 2.26Å with the increase of Tm concentration in the glass. Meanwhile, Tm-S bond distance increases from 2.66Å to 2.71Å approaching to that of crystalline Tm 2 S 3 and simultaneously, the coordination number of Tm gradually decreases from 7 to 4.

Effect of gallium environment on infrared emission in Er3+-doped gallium– antimony– sulfur glasses

“…The incorporation of Ga provides a compensation for the negative charge of free S 2− ions by forming the chemical bonds with RE ions. The expecting compositions, including Ga–La–S17, Ga–As–S18, Ga–Na–S19, and Ga–Ge–S glasses20 et al . have been developed as host materials for RE dopants because a large amount of RE ions could be dissolved and dispersed in low phonon energy hosts homogeneously, making the doped glasses be promising for IR amplifiers or lasers.…”