Optical absorption and Raman scattering spectra of Zn-S bonds in silicate glasses

Abstract

The non-linear optical properties of microcrystalline semiconductor-doped glasses have received much attention in recent years [1]. In semiconductordoped glasses, the requirement for detailed information on particle size, size distributions and chemical compositions of microcrystalline semiconductors such as CdS or CdSl_xSex is inevitable to clarify the quantum confinement effect in semiconductors. Borrelli et al. [2] proposed from X-ray diffraction analyses that in some Corning sharp cut filter borositicate glasses containing ZnO, a solid solution Cd0.65Zn0.35S was formed during annealing. Very recently, Komatsu et al. [3] examined the Raman scattering spectra of CdS microcrystallites in Zn-free and Zn-added sodium silicate glasses and found that Cdl_,ZnxS solid solutions such as Cd08Zn0.2S were formed in the Zn-added glasses. Since the amount of soluble CdS in silicate glasses depends strongly on the amount of ZnO present in glasses [3], the role of zinc in silicate glasses is of much interest and it is important to clarify the effect of zinc on the state of sulphur in glasses and also in heat-treated samples. In this study we prepared sodium silicate glasses containing sulphur or ZnS and measured the optical absorption and Raman scattering spectra of the glasses and heat-treated samples in order to clarify the state of zinc and sulphur. In particular, we focus our attention on Zn-S bonds in glasses. The state of sulphur in the so-called sulphur-amber glasses has been studied extensively, and it is well known that a rich amber colour is produced by the combination of sulphur and iron oxide in sodium silicate glasses melted under strongly reducing conditions [4-6]. However, the study of Zn-S bonds in silicate glasses has not been reported and the presence of Zn-S bonds has not been confirmed experimentally. Silicate glasses with nominal compositions 55SiO2-30Na20-15CaO (reel%) containing various amounts of sulphur (0 .5 -3wt%) or ZnS (3-6 wt %) were prepared by using a conventional melt-quenching method. A platinum crucible was used, and the melting temperature and time were 1350 °C and 90 min, respectively. In order to release the internal stress in glasses the melts were poured onto an iron plate heated at around 300 °C. The glass transition, Tg, and crystallization, Tx, temperatures of a base glass 55SiO2-30Na20-15CaO were 488 °C and 607 °C, respectively. Optical absorption spectra were measured with a Hitachi U-3210 spectrometer. Raman scattering spectra at room temperature were measured by using an Ar ÷ laser (wavelength 514.5nm and laser power