The study of phase formation processes in GeSx:Bi (1 < x < 2) chalcogenide glasses

GeSx:Bi glasses have been found to be promising materials for production of new broadband fiber amplifiers and the fiber lasers. However, these glasses were instable to crystallization that hinders drawing out the optical fibers. The processes of the phase formation and interphase distribution of bismuth between different phases used as an activation ion have been studied by means of XRD, DTA and EDX techniques under varying of temperature and composition of GeSx:Bi (1 < x < 2) glasses. The limits of glass stability for the synthesis technique used were established to correspond to 1.3 < x < 1.6 concentration range. The dopant (Bi) was shown not to be incorporated into germanium sulfide crystals lattice. A reversible process of metallic bismuth formation and its subsequent dissolution was observed during thermal treatment of the glasses under 'heating-cooling-heating' mode. The crystallization of GeS, α-GeS2, β-GeS2 within 1.25 ≤ x ≤ 1.9 ranges at 25 to 550 °С has been described.