Metastability of Spinel-type Solid Solutions in the SiO2-Al2O3 System

J. M. McHale; K. Yürekli; D. M. Dabbs; A. Navrotsky; Sankaran Sundaresan; Ilhan A. Aksay

doi:10.1021/cm970447f

Metastability of Spinel-type Solid Solutions in the SiO₂-Al₂O₃ System

J. M. McHale, K. Yürekli, D. M. Dabbs, A. Navrotsky, Sankaran Sundaresan, Ilhan A. Aksay

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

The addition of small amounts (2-10 wt %) of SiO₂ to γ-Al₂O₃ increases the temperature of heat treatment necessary for transformation to α-Al₂O₃ by ∼100 K. We have studied this system using high-temperature solution calorimetry in molten 2PbO·B₂O₃ at 1043 K. Our results indicate that the spinel-type Al₂O₃-SiO₂ solid solutions with 2-10 wt % SiO₂ are always energetically metastable by 30-35 kJ·mol^-1 (on a 4 O^2- per mole basis) with respect to α-Al₂O₃ and quartz. Calculation of the maximum configurational entropy of the solid solutions allowed determination of the likely most negative value of the Gibbs free energy of the materials. The solid solutions are somewhat entropy stabilized, but still thermodynamically metastable by >10 kJ·mol^-1 at 1400 K. Therefore, SiO₂ addition appears to provide mainly a kinetic hindrance to α-Al₂O₃ formation.

Original language	English (US)
Pages (from-to)	3096-3100
Number of pages	5
Journal	Chemistry of Materials
Volume	9
Issue number	12
DOIs	https://doi.org/10.1021/cm970447f
State	Published - Dec 1997

All Science Journal Classification (ASJC) codes

General Chemistry
General Chemical Engineering
Materials Chemistry

Access to Document

10.1021/cm970447f

Cite this

@article{22f655ba0eaa4b7c904d18ca2fe03ed6,

title = "Metastability of Spinel-type Solid Solutions in the SiO2-Al2O3 System",

abstract = "The addition of small amounts (2-10 wt %) of SiO2 to γ-Al2O3 increases the temperature of heat treatment necessary for transformation to α-Al2O3 by ∼100 K. We have studied this system using high-temperature solution calorimetry in molten 2PbO·B2O3 at 1043 K. Our results indicate that the spinel-type Al2O3-SiO2 solid solutions with 2-10 wt % SiO2 are always energetically metastable by 30-35 kJ·mol-1 (on a 4 O2- per mole basis) with respect to α-Al2O3 and quartz. Calculation of the maximum configurational entropy of the solid solutions allowed determination of the likely most negative value of the Gibbs free energy of the materials. The solid solutions are somewhat entropy stabilized, but still thermodynamically metastable by >10 kJ·mol-1 at 1400 K. Therefore, SiO2 addition appears to provide mainly a kinetic hindrance to α-Al2O3 formation.",

author = "McHale, {J. M.} and K. Y{\"u}rekli and Dabbs, {D. M.} and A. Navrotsky and Sankaran Sundaresan and Aksay, {Ilhan A.}",

year = "1997",

month = dec,

doi = "10.1021/cm970447f",

language = "English (US)",

volume = "9",

pages = "3096--3100",

journal = "Chemistry of Materials",

issn = "0897-4756",

publisher = "American Chemical Society",

number = "12",

}

TY - JOUR

T1 - Metastability of Spinel-type Solid Solutions in the SiO2-Al2O3 System

AU - McHale, J. M.

AU - Yürekli, K.

AU - Dabbs, D. M.

AU - Navrotsky, A.

AU - Sundaresan, Sankaran

AU - Aksay, Ilhan A.

PY - 1997/12

Y1 - 1997/12

N2 - The addition of small amounts (2-10 wt %) of SiO2 to γ-Al2O3 increases the temperature of heat treatment necessary for transformation to α-Al2O3 by ∼100 K. We have studied this system using high-temperature solution calorimetry in molten 2PbO·B2O3 at 1043 K. Our results indicate that the spinel-type Al2O3-SiO2 solid solutions with 2-10 wt % SiO2 are always energetically metastable by 30-35 kJ·mol-1 (on a 4 O2- per mole basis) with respect to α-Al2O3 and quartz. Calculation of the maximum configurational entropy of the solid solutions allowed determination of the likely most negative value of the Gibbs free energy of the materials. The solid solutions are somewhat entropy stabilized, but still thermodynamically metastable by >10 kJ·mol-1 at 1400 K. Therefore, SiO2 addition appears to provide mainly a kinetic hindrance to α-Al2O3 formation.

AB - The addition of small amounts (2-10 wt %) of SiO2 to γ-Al2O3 increases the temperature of heat treatment necessary for transformation to α-Al2O3 by ∼100 K. We have studied this system using high-temperature solution calorimetry in molten 2PbO·B2O3 at 1043 K. Our results indicate that the spinel-type Al2O3-SiO2 solid solutions with 2-10 wt % SiO2 are always energetically metastable by 30-35 kJ·mol-1 (on a 4 O2- per mole basis) with respect to α-Al2O3 and quartz. Calculation of the maximum configurational entropy of the solid solutions allowed determination of the likely most negative value of the Gibbs free energy of the materials. The solid solutions are somewhat entropy stabilized, but still thermodynamically metastable by >10 kJ·mol-1 at 1400 K. Therefore, SiO2 addition appears to provide mainly a kinetic hindrance to α-Al2O3 formation.

UR - http://www.scopus.com/inward/record.url?scp=0043112178&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0043112178&partnerID=8YFLogxK

U2 - 10.1021/cm970447f

DO - 10.1021/cm970447f

M3 - Article

AN - SCOPUS:0043112178

SN - 0897-4756

VL - 9

SP - 3096

EP - 3100

JO - Chemistry of Materials

JF - Chemistry of Materials

IS - 12

ER -

Metastability of Spinel-type Solid Solutions in the SiO₂-Al₂O₃ System

Abstract

All Science Journal Classification (ASJC) codes

Access to Document

Other files and links

Fingerprint

Cite this