Energetics of the Charge‐Coupled Substitution Si4+→ Na++ T3+ in the‐Glasses NaTO2–SiO2 (T = Al, Fe, Ga, B)

James J. De Yoreo, Alexandra Navrotsky, Don B. Dingwell

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Heats of solution in molten 2PbO·B2O3 at 973 K are reported for glasses xNaT3+O2–(1 –x)SiO2 for T = Fe, Ga. These measurements, combined with previous data for T = Al, B, give a relative measure of the enthalpy of the charge‐coupled substitution Si4+→ Na++ T3+. The heats of solution become more endothermic with increasing x for x→ 0.5 and exhibit a maximum near x= 0.5. This indicates an exothermic enthalpy for the substitution and an overall stabilization of the glasses. The degree to which the glasses are stabilized decreases in the order Al > Ga > Fe > B. On the basis of molecular orbital calculations, X‐ray scattering, and Raman spectroscopy, it is argued that this trend is primarily due to a decrease in the range of energetically favorable T–O–T bond angles as Al, Ga, Fe, and B are substituted for Si.

Original languageEnglish (US)
Pages (from-to)2068-2072
Number of pages5
JournalJournal of the American Ceramic Society
Issue number7
StatePublished - Jul 1990
Externally publishedYes


  • charge
  • couplers
  • enthalapy
  • glass
  • substitution

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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