The synthesis, single-crystal structure, optical absorption, and resistivity of Th2GeSe5

• The new compound Th2GeSe5 was synthesized from the elements and recrystallized from Sb2Se3.
• Th2GeSe5 crystallizes in the Ba5Si3 structure type.
• The band gap of Th2GeSe5 is1.92 eV and its resistivity shows it to be a wide gap semiconductor.

The compound Th2GeSe5 has been synthesized by the reaction of the elements at 1273 K. From a single-crystal study Th2GeSe5 crystallizes in the Ba5Si3 structure type with four formula units in the space group D84h−P4/ncc of the tetragonal system in a cell with dimensions a=7.4968(4) Å and c=13.6302(9) Å at 100(2) K. From optical absorption measurements Th2GeSe5 is found to have an optical band gap of 1.92 eV (indirect) or 1.98 eV (direct), consistent with its red color. Th2GeSe5 is a wide gap semiconductor, as indicated by its electrical resistivity at 298 K of 4.37(2)×109 Ω cm measured on a single crystal.

The structure of Th2GeSe5.Figure optionsDownload as PowerPoint slide