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5Glass-forming tendency in fiber optics Ge-As-Se-S chalcogenide
glass materials
R.I. Alekberov, S.I. Mekhtiyeva, S.M. Mammadov*
Republic of Azerbaijan Ministry of Science and Education Institute of Physics named after Academician Hasan Abdullayev, G. Javid ave 131, AZ1143 Baku
The results of scientific research show that chalcogenide glasses containing germanium (Ge) and arsenic (As) have a wide range of optical transparency, low optical loss, high stability and non-linear optical properties, which can be effectively used in solving numerous application problems arising mainly in the field of fiber optics [1]. It is necessary choosing a mode that excludes crystallization and liquefaction during the synthesis process, as well as being resistant to crystallization and humidity when preparing fiber optic transmitters, fiber lasers and amplifiers with high performance indicators from chalcogenide glass materials containing germanium (Ge) and arsenic (As) with high chemical and phase purity. The analysis of various scientific articles shows that the addition of a certain atomic percentage of Ge to Ge-As-Se-S system with complex components will increase their mechanical strength and the operating temperature range of fiber transmissions [2].
The aim of the article is to study the local structure, the glass forming ability, the thermal stability, the glass and crystallization regions of substances corresponding to different topological glass states (isostatic, rigid, elastic) depending on the atomic percentage of chalcogenous (Se, S) and non-chalcogenous (Ge, As) constituent elements in Ge-As-Se-S glassy systems according to the idea of layered structure and chemically ordered network models.
X-ray diffraction results shows that, the values of d and L increase proportionally with the increase in the atomic percentage of Ge (except for Ge25AsioS25Se4o content). For the composition (Ge25AsioS25Se4o) according to the chemical regularity (R=1 and <r>=2.6) violates the above mentioned proportional dependence. That is, the ratio of the sum of (S+Se) with small atomic radius to the amount of As in the mentioned composition has a maximum value. As a result, it ensures that Ge25AsioS25Se4o composition is formed only from pyramidal and tetrahedral structural elements. The obtained results prove that the composition of Ge25AsioS25Se4o, which corresponds to the state of chemical order (R=1) and is close to the topological order (f~0, N~3), is more resistant to crystallization (ATg.c ~87 K), and also are characterized by relatively high the ability of glass formation and high values of thermal stability (Hr =0.469; H'=0.159). The glass formation ability (Hr), thermal stability parameters (H', S), decrease significantly in Ge33AsnS35Sei5 with high atomic percentage of Ge, S, and relatively low amount of Se.
[1] J.L. Adam and X. Zhang, Chalcogenide Glasses, Preparation, Properties and Applications, Cambridge: Woodhead Publishing Limited (20i4), p. 703.
[2] I. Inagawa, R. Iizuka, T. Yamagishi, R. Yokota, Optical and thermal properties of chalcogenide Ge-As-Se-Te glasses for IR fibers, J. Non-Crystal. Solids (i987) pp. 95-96, 80i-808.
