Raman spectroscopy and DFT modelling of Tl2S-GeS2 crystals and glasses
Résumé
Thallium thiogermanate glasses and crystals were studied by Raman spectroscopy accompanied by DFT modelling. The experimental Raman spectra of the known crystalline compounds in the Tl2S-GeS2 system are consistent with the crystal structure and DFT modelling of the respective Tl-Ge-S clusters, representing structural motifs in c-Tl4Ge4S10, c-Tl4Ge2S6, and c-Tl4GeS4. The Raman spectra of the (Tl2S)x(GeS2)1-x glasses can be divided into two groups: (1) semiconducting glasses at x ≤ 0.3, and (2) ion-conducting vitreous alloys at x > 0.3. At x ≤ 0.3, the continuous g-GeS2 network is transformed into a fragmented structure consisting of adamantane-like units Ge4S10 held together by thallium species. In the ion-conducting composition domain at x > 0.3 takes place further fragmentation of tetrahedral tetramers Ge4S10 into edge-sharing ES-Ge2S6 dimers and small corner-sharing CS-oligomers, i.e., CS-Ge2S7 dimers or CS-Ge3S10 trimers.
Domaines
Physique [physics]
Origine : Fichiers produits par l'(les) auteur(s)
Licence : CC BY - Paternité
Licence : CC BY - Paternité