Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses

T. Kosuge, Yasuhiko Benino, V. Dimitrov, R. Sato, T. Komatsu

Research output: Contribution to journalArticle

122 Citations (Scopus)

Abstract

The thermal stability and heat capacity changes in the glass transition region of K2O-WO3-TeO2 glasses (glass formation range 20-90 mol% TeO2) have been studied to examine the structural relaxation behavior. The glasses with 60-70 mol% TeO2 and with both K2O and WO3 are thermally stable against crystallization. It is proposed from Raman spectral analyses that TeO4 trigonal bipyramids change to TeO3 trigonal pyramids with the addition of K2O and that Te-O-W bonds are formed in the substitution of WO3 for TeO2. Heat capacity changes of ΔCp = 48-58 J mol-1 K-1 (ΔCp = Cp1 - Cpg, Cpg and Cp1 are the heat capacities of the glasses and supercooled liquids, respectively), and ratios Cp1//Cpg = 1.6-1.8 are obtained for xK2O·xWO3·(100 - 2x)TeO2 glasses. The ΔCp and Cp1/Cpg increase with decreasing TeO2 content, indicating an increase in thermodynamic fragility with decreasing TeO2 content. But, the kinetic fragility estimated from the activation energy for viscous flow is almost constant irrespective of TeO2 content. These behaviors have been analyzed using the configurational entropy model proposed by Adam and Gibbs. The results indicate that in K2O-WO3-TeO2 glasses, Te-O-Te bonds are weak and bond breakings occur easily in the glass transition region, leading to large configurational entropy changes and thus large ΔCp.

Original languageEnglish
Pages (from-to)154-164
Number of pages11
JournalJournal of Non-Crystalline Solids
Volume242
Issue number2-3
Publication statusPublished - Dec 2 1998
Externally publishedYes

Fingerprint

Specific heat
Glass transition
Thermodynamic stability
thermal stability
specific heat
Glass
glass
Entropy
Structural relaxation
Viscous flow
entropy
Crystallization
viscous flow
Substitution reactions
Activation energy
pyramids
Thermodynamics
Kinetics
Liquids
substitutes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials

Cite this

Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses. / Kosuge, T.; Benino, Yasuhiko; Dimitrov, V.; Sato, R.; Komatsu, T.

In: Journal of Non-Crystalline Solids, Vol. 242, No. 2-3, 02.12.1998, p. 154-164.

Research output: Contribution to journalArticle

Kosuge, T. ; Benino, Yasuhiko ; Dimitrov, V. ; Sato, R. ; Komatsu, T. / Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses. In: Journal of Non-Crystalline Solids. 1998 ; Vol. 242, No. 2-3. pp. 154-164.
@article{46666ebe8abf4c39bc30be5369fb05fc,
title = "Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses",
abstract = "The thermal stability and heat capacity changes in the glass transition region of K2O-WO3-TeO2 glasses (glass formation range 20-90 mol{\%} TeO2) have been studied to examine the structural relaxation behavior. The glasses with 60-70 mol{\%} TeO2 and with both K2O and WO3 are thermally stable against crystallization. It is proposed from Raman spectral analyses that TeO4 trigonal bipyramids change to TeO3 trigonal pyramids with the addition of K2O and that Te-O-W bonds are formed in the substitution of WO3 for TeO2. Heat capacity changes of ΔCp = 48-58 J mol-1 K-1 (ΔCp = Cp1 - Cpg, Cpg and Cp1 are the heat capacities of the glasses and supercooled liquids, respectively), and ratios Cp1//Cpg = 1.6-1.8 are obtained for xK2O·xWO3·(100 - 2x)TeO2 glasses. The ΔCp and Cp1/Cpg increase with decreasing TeO2 content, indicating an increase in thermodynamic fragility with decreasing TeO2 content. But, the kinetic fragility estimated from the activation energy for viscous flow is almost constant irrespective of TeO2 content. These behaviors have been analyzed using the configurational entropy model proposed by Adam and Gibbs. The results indicate that in K2O-WO3-TeO2 glasses, Te-O-Te bonds are weak and bond breakings occur easily in the glass transition region, leading to large configurational entropy changes and thus large ΔCp.",
author = "T. Kosuge and Yasuhiko Benino and V. Dimitrov and R. Sato and T. Komatsu",
year = "1998",
month = "12",
day = "2",
language = "English",
volume = "242",
pages = "154--164",
journal = "Journal of Non-Crystalline Solids",
issn = "0022-3093",
publisher = "Elsevier",
number = "2-3",

}

TY - JOUR

T1 - Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses

AU - Kosuge, T.

AU - Benino, Yasuhiko

AU - Dimitrov, V.

AU - Sato, R.

AU - Komatsu, T.

PY - 1998/12/2

Y1 - 1998/12/2

N2 - The thermal stability and heat capacity changes in the glass transition region of K2O-WO3-TeO2 glasses (glass formation range 20-90 mol% TeO2) have been studied to examine the structural relaxation behavior. The glasses with 60-70 mol% TeO2 and with both K2O and WO3 are thermally stable against crystallization. It is proposed from Raman spectral analyses that TeO4 trigonal bipyramids change to TeO3 trigonal pyramids with the addition of K2O and that Te-O-W bonds are formed in the substitution of WO3 for TeO2. Heat capacity changes of ΔCp = 48-58 J mol-1 K-1 (ΔCp = Cp1 - Cpg, Cpg and Cp1 are the heat capacities of the glasses and supercooled liquids, respectively), and ratios Cp1//Cpg = 1.6-1.8 are obtained for xK2O·xWO3·(100 - 2x)TeO2 glasses. The ΔCp and Cp1/Cpg increase with decreasing TeO2 content, indicating an increase in thermodynamic fragility with decreasing TeO2 content. But, the kinetic fragility estimated from the activation energy for viscous flow is almost constant irrespective of TeO2 content. These behaviors have been analyzed using the configurational entropy model proposed by Adam and Gibbs. The results indicate that in K2O-WO3-TeO2 glasses, Te-O-Te bonds are weak and bond breakings occur easily in the glass transition region, leading to large configurational entropy changes and thus large ΔCp.

AB - The thermal stability and heat capacity changes in the glass transition region of K2O-WO3-TeO2 glasses (glass formation range 20-90 mol% TeO2) have been studied to examine the structural relaxation behavior. The glasses with 60-70 mol% TeO2 and with both K2O and WO3 are thermally stable against crystallization. It is proposed from Raman spectral analyses that TeO4 trigonal bipyramids change to TeO3 trigonal pyramids with the addition of K2O and that Te-O-W bonds are formed in the substitution of WO3 for TeO2. Heat capacity changes of ΔCp = 48-58 J mol-1 K-1 (ΔCp = Cp1 - Cpg, Cpg and Cp1 are the heat capacities of the glasses and supercooled liquids, respectively), and ratios Cp1//Cpg = 1.6-1.8 are obtained for xK2O·xWO3·(100 - 2x)TeO2 glasses. The ΔCp and Cp1/Cpg increase with decreasing TeO2 content, indicating an increase in thermodynamic fragility with decreasing TeO2 content. But, the kinetic fragility estimated from the activation energy for viscous flow is almost constant irrespective of TeO2 content. These behaviors have been analyzed using the configurational entropy model proposed by Adam and Gibbs. The results indicate that in K2O-WO3-TeO2 glasses, Te-O-Te bonds are weak and bond breakings occur easily in the glass transition region, leading to large configurational entropy changes and thus large ΔCp.

UR - http://www.scopus.com/inward/record.url?scp=0032291065&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0032291065&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0032291065

VL - 242

SP - 154

EP - 164

JO - Journal of Non-Crystalline Solids

JF - Journal of Non-Crystalline Solids

SN - 0022-3093

IS - 2-3

ER -