Effects of nitrides on the IR transmitting properties of chalcogenide glasses

Nitrides, besides their role as a source of introducing nitrogen into chalcogenide glasses to form a new family of chalconitride glasses, can also exert an effect on IR transmitting property of a glass. In the present study Si3N4 and BN were doped in a base chalcogenide glass and changes in the IR transmission spectra were measured. We observed that a series of bands in the mid-IR spectrum of the base glass disappeared. We describe the process in terms of a chemical reactivity among melt constituents and the relative redox reactions existing in the glass liquid. The Ellingham diagram tabulated with many relevant thermodynamic data for oxides was adapted by adding plots for oxidations of different nitrides in the diagram to explain the possible redox reaction between an oxide and a nitride. The ability of previously used oxygen getters, such as Al, Mg and Zr, to remove oxygen bands present in chalcogenide glasses can be substantiated in the same way.