Short range order in Ge–As–Se glasses

Pethes, Ildikó; Kaban, I.; Wang, R.-P.; Luther‐Davies, Barry; Jóvári, P.

doi:10.1016/j.jallcom.2014.11.002

Cited by 18 publications

(13 citation statements)

References 42 publications

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“…The atomic arrangements in Ge-Sb-Se and Ge-Sb-S glasses are delineated: The network structures of these two glass families are built with four-fold coordinated Ge atoms and three-fold coordinated Sb atoms in which the chemical preference favoring heteropolar bonds to chalcogen atoms applies to the entire compositions that are able to form glass state through the conventional melt-quenching technique 21 – 24 . Compositions deviating from the stoichiometric ratio are allowed to form homopolar bonds, e.g., Ge-Ge, Ge-Sb and/or Sb-Sb.…”

Section: Resultsmentioning

confidence: 99%

Unravelling interrelations between chemical composition and refractive index dispersion of infrared-transmitting chalcogenide glasses

Lee

Choi

et al. 2018

Sci Rep

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A facile procedure for compositional screening of chalcogenide glass (CG) is proposed to manage its infrared transmission edge (ωc) as well as refractive index dispersion (ν) in the long-wavelength infrared (LWIR) range. Both ωc and ν of CG turn out to be interpretable simply in connection with its chemical composition based on a postulation that CG behaves as a single average harmonic oscillator (SAHO). In this SAHO model, ωc is expressed as a function of molar mass and average bond energy, both of which are easily accessible for a given CG composition. Two prototypical CG-forming systems in Ge-Sb-Se and Ge-Sb-S compositions exemplify the empirical compositional dependence of ωc, which further plays a decisive role in determining ν. Following the present approach, a set of highly dispersive CG compositions in the Ge-Sb-S system is newly unveiled together with low-dispersion Ge-Sb-Se glasses. It is then experimentally demonstrated that a doublet lens configuration consisting of convex and concave lenses with low and high ν values, respectively, is able to reduce the optical aberrations. This finding presents an opportunity that ν can be envisaged just based on the compositional ratio of CG, thus facilitating completion of the LWIR Abbe diagram.

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Section: Resultsmentioning

confidence: 99%

Unravelling interrelations between chemical composition and refractive index dispersion of infrared-transmitting chalcogenide glasses

Lee

Choi

et al. 2018

Sci Rep

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“…For Ge–As(Sb)–Se(Te) glasses, this means that the Ge, As(Sb), and Se(Te) atoms have four, three, and two nearest neighbors, respectively. This rule has been verified for all participating elements in Ge–As–Se, − Ge–As–Te, and Ge–Sb–Te. , There is less evidence for the validity of the Mott rule in Ge–Sb–Se glasses: ab initio molecular dynamics simulations have shown that they roughly follow this rule …”

Section: Introductionmentioning

confidence: 92%

Chemical Short-Range Order in Selenide and Telluride Glasses

et al. 2016

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The structure of Ge20SbxSe80-x (x = 5, 15, 20) glasses was investigated by neutron diffraction, X-ray diffraction, and extended X-ray fine structure measurements at the Ge, Sb, and Se K-edges. For each composition, large-scale structural models were obtained by fitting simultaneously the experimental data sets in the framework of the reverse Monte Carlo simulation technique. It was found that the structures of these glasses can be described mostly by the chemically ordered network model. Ge-Se and Sb-Se bonds are preferred; Se-Se bonds in the Se-poor composition (x = 20) and M-M (M = Ge, Sb) bonds in strongly Se-rich glass (x = 5) are not needed. The quality of the fits was significantly improved by introducing Ge-Ge bonding in the nearly stoichiometric composition (x = 15), showing a violation of chemical ordering. The structure of Ge20SbxSe80-x was compared to that of several glasses from the three analogous systems (Ge-As-Se, Ge-As-Te, Ge-Sb-Te), and it was found that chemical short-range order becomes more pronounced upon substituting As with Sb and Se with Te. Ge-As-Se glasses behave as random covalent networks over a very broad composition range. Chemical short-range order and disorder coexist in both Te-rich and Te-poor Ge-As-Te glasses, whereas amorphous Ge14Sb29Te57 and Ge22Sb22Te56 are governed by strict chemical preferences.

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“…The cumulative relative R-factor (R c ), which is the average of the relative R-factors (R(investigated model)/R(reference model)) of the data sets [27], was used to compare the different models. The R c of the reference model is 1, by definition.…”

Section: Measurementsmentioning

confidence: 99%

Local motifs in GeS2–Ga2S3 glasses

Pethes

Nazabal

Chahal

et al. 2016

Journal of Alloys and Compounds

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The structure of (GeS 2 ) 0.75 (Ga 2 S 3 ) 0.25 and (GeS 2 ) 0.83 (Ga 2 S 3 ) 0.17 glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS 2 -Ga 2 S 3 glasses. Analysis of the corner-and edge-sharing between [GeS 4/2 ] units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.

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Short range order in Ge–As–Se glasses

Cited by 18 publications

References 42 publications

Unravelling interrelations between chemical composition and refractive index dispersion of infrared-transmitting chalcogenide glasses

Unravelling interrelations between chemical composition and refractive index dispersion of infrared-transmitting chalcogenide glasses

Chemical Short-Range Order in Selenide and Telluride Glasses

Local motifs in GeS2–Ga2S3 glasses

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