Mercury Thiogermanate Glasses HgS-GeS: Vibrational, Macroscopic, and Electric Properties.

Glasses in the pseudo-binary system (HgS) (GeS) were synthesized over the concentration range of 0.0 ≤ ≤ 0.5. The fundamental glass properties (macroscopic, electric, and vibrational) were studied using differential scanning calorimetry (DSC), direct current (dc) electrical measurements, Raman spectroscopy supported by DFT modeling, and X-ray diffraction. Mercury species in thiogermanate glasses essentially form chain-like (HgS) fragments substituting bridging sulfur between corner- and edge-sharing GeS tetrahedra. This structural evolution results in a significant monotonic decrease of the glass transition temperatures from 480 to 270 °C. The room-temperature dc conductivity changes non-monotonically with increasing HgS content over a limited range of 4 × 10 to 7 × 10 S cm. The electronic transport in insulating HgS-GeS glasses occurs via extended electronic states. Tetrahedral HgS fragments also appear in the glass network with increasing . Their exact population needs further advanced structural studies using diffraction techniques.