Abstract
Ternary Ge10AsxTe90-x glasses with a mean coordination number (MCN) from 2.3 to 2.8 were prepared, and their physical and structural properties were characterized. It was found that, the density of the glass decreases but glass transition temperature Tg increases, and the near infrared transmission edge shifts to shorter wavelength with increasing As content. The Ge, As, and Te 3d spectra were decomposed into different doublets that correspond to different structural units and the results showed that, the numbers of Te-Te-Te trimmers and Te-Te-As(Ge) structural units decrease and finally disappear, while the perfect AsTe3/2 pyramidal and GeTe4/2 tetrahedral structure in Te-rich samples gradually transferred to defect structures including As-As and Ge-Ge homopolar bonds with increasing As concentration. No threshold behaviour can be found in the structural evolution of Ge10AsxTe90-x glasses due to a large atomic contrast between As and Te, and no any change in the chemical coordination of Te can be observed even in Te-poor glasses.
Highlights
Chalcogenide (ChGs) glasses contain one or more S, Se or Te chalcogenide elements covalently bonded with other network forming elements such as Ge, As and Sb
While it is understood that the structure and physical properties of chalcogenide glasses can be tuned by the chemical compositions, it has been arguable that the physical properties of these glasses would be predominantly controlled by mean coordination number (MCN), which is the sum of the products of the individual abundance times the valency of the constituent atoms on the basis of the theory of constraint counting, irrespective of their actual chemical composition.[18,19,20,21]
The analysis of high resolution x-ray photoelectron spectroscopy (XPS) spectra indicated that, Te-Te-Te trimmers and Te-Te-As(Ge) structure units can be found in the Te-rich samples, and the numbers of these structure units decrease and disappear with decreasing Te contents
Summary
Chalcogenide (ChGs) glasses contain one or more S, Se or Te chalcogenide elements covalently bonded with other network forming elements such as Ge, As and Sb. Strong coherent light source covering this wavelength range is essential to develop spectral tools to detect these molecules.[7]
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