Physical properties of the GexSe1−x glasses in the 0<x<0.42 range in correlation with their structure (original) (raw)
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Physical properties of the GexSe1−x glasses in the 0
Journal of Non-Crystalline Solids, 2013
Physical properties, including mechanical, thermal and optical properties, have been investigated for chalcogenide glasses in the Ge x Se 1-x system, for x ranging between 0 and 0.42. In the 0<x<1/3 range, the elastic moduli or the glass transition temperature (T g) evolve as would be expected from the chain crossing model or from the clustering model. The change is continuous and there is no incidence of the rigidity percolation threshold (=2.4). Conversely, the chemical threshold (=2.67) clearly induces a change in the compositional trend of these properties. In the x>1/3 range, T g decreases and the elastic moduli markedly increase, which is not expected from the continuously reticulated model. The change of the physical properties in this range is an indicator of the existence of separated Ge-rich domains.
Search for a structural response to the intermediate phase in GeSe{sub 1-x} glasses
Physical Review B, 2008
Atomic pair distribution functions ͑PDFs͒ obtained from high energy x-ray synchrotron radiation and x-ray absorption fine structure measurements were performed on 18 closely spaced compositions of chalcogenide glasses ͑Ge x Se 1−x with 0.15Յ x Յ 0.40͒, which span the range of the floppy to rigid phase transition in these glasses. Structural parameters such as PDF peak widths, Debye-Waller factors from extended x-ray absorption fine structure, and the first sharp diffraction peak in S͑Q͒ were extracted as a function of composition. These parameters smoothly evolve with composition, but there are no clear discontinuities or breaks in the slope associated with the appearance of the intermediate phase ͑IP͒. Therefore, these measurements do not confirm a structural origin for the IP.
Search for a structural response to the intermediate phase in GexSe1-x glasses
Physical Review B, 2008
Atomic pair distribution functions ͑PDFs͒ obtained from high energy x-ray synchrotron radiation and x-ray absorption fine structure measurements were performed on 18 closely spaced compositions of chalcogenide glasses ͑Ge x Se 1−x with 0.15Յ x Յ 0.40͒, which span the range of the floppy to rigid phase transition in these glasses. Structural parameters such as PDF peak widths, Debye-Waller factors from extended x-ray absorption fine structure, and the first sharp diffraction peak in S͑Q͒ were extracted as a function of composition. These parameters smoothly evolve with composition, but there are no clear discontinuities or breaks in the slope associated with the appearance of the intermediate phase ͑IP͒. Therefore, these measurements do not confirm a structural origin for the IP.
Materials Today: Proceedings, 2019
Selenium-based chalcogenide glasses are best suitable materials for optical data storage due to their amorphous-tocrystalline phase transformation. Average coordination number and number of constraints for Ge 10-xSe 60 Te 30 In x (x = 0, 2, 4, 6) system have been discussed with two topological effects, floppy and rigid transition. Mean bond energy and glass transition temperature have been investigated using chemical bond approach to understand structural features of glasses. Heat of atomization, mean bond energy and glass transition temperature have been studied theoretically.
An intermediate phase in GexSe1-x glasses: experiment and simulation
Journal of Physics-condensed Matter, 2007
The pair correlation function for Ge x Se 1−x alloys near the intermediate phase (IP) is reported. First-principles MD models of these alloys show a 'selforganized' phase associated with the number of Ge bonds with twofold Se atoms. This probably represents the IP of Boolchand. The self-organization involves maintaining a nearly constant number of twofold Se atoms bonded to one Ge atom through a range of Ge concentration, roughly coinciding with the IP. This behavior is manifested in observables like the optical gap. Our work suggests that the IP is due to selective formation of these local structures.
2008
Raman and calorimetric studies on GexSe1−x glasses have provided evidence for the existence of the intermediate phase (IP) in chalcogenide and other glasses. Here, we present X-Ray Absorption Near Edge Structure (XANES) measurements on germanium selenide glasses in the IP composition range, and detect an electronic signature of the IP. Ab initio molecular dynamics (MD) based models of these glasses are discussed, and an atomistic picture of the IP, based upon the models and available experiments is presented. We show that these models reproduce detailed composition-dependent structure in the XANES measurements, and otherwise appear to properly represent the structure of the GeSe glasses near the IP.
Journal of Applied Physics, 2011
We have prepared and analyzed five different compositions of Ge x As y Se 1−x−y glasses that have the same mean coordination number ͑MCN͒ of 2.5 in order to understand whether MCN or chemical composition has the dominant effect on the physical properties of the glass. Density measurements showed a maximum for the chemically stoichiometric Ge 12.5 As 25 Se 62.5 sample and suggested that some rearrangement of the atoms was occurring as one atom substituted for another. The measurements of T g , however, showed that the glasses had almost same glass transition temperature and suggested that the glass network connectivity did not change much with composition. Although Raman scattering and x-ray photoelectron spectra of the glasses indicate that the percentage of the different structural units changes with the composition, there was no evidence of the existence of structural units that could change the overall connectivity of the glass network. Therefore, we concluded that glasses with same MCN but different composition have similar glass network connectivity, and that chemical composition has only a secondary effect on the physical properties of the glasses.
Energetic Diffusion in ternary sets of Ge-Se-In Chalcogenide Glasses
— The composition dependence of energetic parameter (A) in two sets of Ge-Se-In glasses, namely, Ge10Se90-xInx (x = 5, 10, 15, 20) and Ge15Se85-xInx (x = 0, 5, 10, 15, 20) have been studied by using rigidity percolation theory and bond constraints theory. Parameter (A) shows a local maxima at = 2.67. The results are discussed on the basis of the topological and rigidity theory exhibited by covalent network glasses. The relative sensitivity of parameter (A) to these phenomena discussed.