TY - JOUR
T1 - Energetics of the Charge‐Coupled Substitution Si4+→ Na++ T3+ in the‐Glasses NaTO2–SiO2 (T = Al, Fe, Ga, B)
AU - De Yoreo, James J.
AU - Navrotsky, Alexandra
AU - Dingwell, Don B.
PY - 1990/7
Y1 - 1990/7
N2 - 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.
AB - 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.
KW - charge
KW - couplers
KW - enthalapy
KW - glass
KW - substitution
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U2 - 10.1111/j.1151-2916.1990.tb05269.x
DO - 10.1111/j.1151-2916.1990.tb05269.x
M3 - Article
AN - SCOPUS:0025461019
SN - 0002-7820
VL - 73
SP - 2068
EP - 2072
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 7
ER -