T-x phase diagram of the TlGaS2-TlFeS2 system and band gap of TlGa1 − xFexS2 (0 ≤ x ≤ 0.01) single crystals

We have constructed the T - x phase diagram of the TlGaS 2 -TlFeS 2 system (simple eutectic system, eutectic at 80 mol % TlFeS 2 with a melting point of 953 K). The system contains limited series of monoclinic solid solutions based on the ternary end-members. At an annealing temperature of 933 K, the TlGaS 2 -based solid solution extends to 5 mol % TlFeS 2 and the TlFeS 2 -based solid solution extends to ≅10 mol % TlGaS 2 . We have examined the effect of partial iron substitution for gallium on the optical properties of melt-grown single crystals of the TlGaS 2 -based solid solutions and determined their band gap as a function of temperature and Fe concentration.