Raman spectra and short-range order in P x S1−x glasses

Koudelka, Ladislav; Pisárčik, M.; Gutenev, M. S.; Блинов, Л. Н.

doi:10.1007/bf01729950

Cited by 12 publications

(17 citation statements)

References 9 publications

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“…The doublet observed near 700 cm À1 we assign to P@S stretching vibration of the QT units. The present assignments are in harmony with earlier Raman [75] and NMR results [76]. At x > 20%, P atoms rapidly leach out from the backbone to form P 4 S 10 cages, leading to the doublet feature near 700 cm À1 to become asymmetric.…”

Section: Binary P X S 1àx Glassessupporting

confidence: 89%

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Boolchand

Chen

Vempati

2009

Journal of Non-Crystalline Solids

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Density functional theory Raman spectroscopy Medium-range order Short-range order Calorimetry Enthalpy relaxation Structural relaxation a b s t r a c tWe review intermediate phases (IPs) in chalcogenide glasses and provide a structural interpretation of these phases. In binary group IV selenides, IPs reside in the 2.40 < r < 2.54 range, and in binary group V selenides they shift to a lower r, in the 2.29 < r < 2.40 range. Here, r represents the mean coordination number of glasses. In ternary alloys containing equal proportions of group IV and V selenides, IPs are wider and encompass ranges of respective binary glasses. These data suggest that the local structural variance contributing to IP widths largely derives from four isostatic local structures of varying connectivity r, two include group V based quasi-tetrahedral (r = 2.29) and pyramidal (r = 2.40) units, and the other two are group IV based corner-sharing (r = 2.40) and edge-sharing (r = 2.67) tetrahedral units. Remarkably, binary group V (P, As) sulfides exhibit IPs that are shifted to even a lower r than their selenide counterparts; a result that we trace to excess S n chains either partially (As-S) or completely (P-S) demixing from network backbone, in contrast to excess Se n chains forming part of the backbone in corresponding selenide glasses. In ternary chalcogenides of Ge with the group V elements (As, P), IPs of the sulfides are similar to their selenide counterparts, suggesting that presence of Ge serves to reign in the excess S n chain fragments back in the backbone as in their selenide counterparts.Ó 2009 Elsevier B.V. All rights reserved. Three types of glass transitionsGlasses are intrinsically non-equilibrium solids and their physical properties generally evolve over long times, i.e., these solids slowly age. The aging of glasses is itself a fascinating subject and has been debated since the early work of Kohlrausch [1-3]. There is now evidence to suggest that the stretched exponential relaxation observed in glasses may well be characterized by specific exponents, which are determined [2] largely by the nature (of long or short range) of forces that control how traps or defects diffuse as networks relax. For a long time it was widely believed that glass transitions are also hysteretic and age [3] as observed in a traditional differential scanning calorimetry. There are new findings showing that under select conditions [4-6] aging of glasses may not occur.New insights into the nature of the glass transition [4,7] have now emerged using modulated-DSC (m-DSC). A significant advantage of m-DSC over traditional DSC is that the method permits deconvoluting the total heat flow into a reversing heat flow term (which captures the local equilibrium specific heat) and a nonreversing heat flow term (which captures non-equilibrium effects of the changing structure). The thermally reversing heat flow term usually reveals a rounded step-like jump. One defines the glass transition temperature, T g , from the inflexion point of the step, and the specific hea...

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Section: Binary P X S 1àx Glassessupporting

confidence: 89%

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Boolchand

Chen

Vempati

2009

Journal of Non-Crystalline Solids

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“…The maximum shifts to 471 cm À1 as sulfur content increases in the 80% S glass. A similar shift was seen in PS glass, 490 cm À1 in the 24% P glass to 478 cm À1 in the 10% P glass [19]. The shift to lower frequency as sulfur is added reflects the decrease in the number of cross-links contained in the network.…”

Section: Raman Spectroscopysupporting

confidence: 71%

“…The band around 700 cm À1 , due to P@S bonds [9,19], is present in all samples with P 63.2% S. This result indicates that when the sulfur deficit drops below 20%, no S@PS 3=2 units remain in the glass. The shoulder at 375 cm À1 , which develops into a broad peak in the extreme sulfur excess samples, is associated with the vibration involving the phosphorus and the three bridging sulfurs of S@PS 3=2 units [9,19]. This band is broad when compared to PS glass and to stoichiometric the (GeS 2 ) 1Àx (P 2 S 5 ) x glass with high P content [9,19].…”

Section: Raman Spectroscopymentioning

confidence: 80%

“…The formation of P 4 S 3 in samples with at least 20% sulfur deficiencies is confirmed in the Raman spectra: the sharp bands at 280 and 440 cm À1 are the E and A 1 of modes of P 4 S 3 [21,22]. The growth of a band at 250 cm À1 in glasses with a 26.7% or greater sulfur deficit indicates Ge-Ge and Ge-P bonding [19].…”

Section: Raman Spectroscopymentioning

confidence: 84%

“…The shoulder at 375 cm À1 , which develops into a broad peak in the extreme sulfur excess samples, is associated with the vibration involving the phosphorus and the three bridging sulfurs of S@PS 3=2 units [9,19]. This band is broad when compared to PS glass and to stoichiometric the (GeS 2 ) 1Àx (P 2 S 5 ) x glass with high P content [9,19]. In the non-stoichiometric GePS glasses studied here, there is a large variability in the combination of second neighbors (sulfur, germanium, and phosphorus) to which the sulfur of S@PS 3=2 unit bridge.…”

Section: Raman Spectroscopymentioning

confidence: 99%

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Raman spectra and short-range order in P x S1−x glasses

Cited by 12 publications

References 9 publications

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Structure and properties of Ge2.5PSx glasses

Die rationale Synthese und strukturelle Charakterisierung schwefelreicher Phosphorpolysulfide – α‐P₂S₇ und β‐P₂S₇

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Raman spectra and short-range order in P x S1−x glasses

Cited by 12 publications

References 9 publications

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Intermediate Phases, structural variance and network demixing in chalcogenides: The unusual case of group V sulfides

Structure and properties of Ge2.5PSx glasses

Die rationale Synthese und strukturelle Charakterisierung schwefelreicher Phosphorpolysulfide – α‐P2S7 und β‐P2S7

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Die rationale Synthese und strukturelle Charakterisierung schwefelreicher Phosphorpolysulfide – α‐P₂S₇ und β‐P₂S₇