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Title: Thermochemistry of stuffed quartz-derivative phases along the join LiAlSiO[sub 4]-SiO[sub 2]

Abstract

Enthalpies of drop-solution ([Delta]H[sub drop-soln]) of a suite of stuffed quartz-derivative phases with the composition Li[sub 1[minus]x]Al[sub 1[minus]x]Si[sub 1+x]O[sub 4] (0 [le] x [le] 1) have been measured in molten 2PbO[center dot]B[sub 2]O[sub 3] at 974 K. Substitution of Si[sup 4+] for Li[sup +] + Al[sup 3+] results in more exothermic enthalpies of drop-solution, which is consistent with behavior seen in other crystalline and glassy aluminosilicates. Al/Si ordering serves to stabilize these phases, and long-range ordering for compositions with x approximately <0.3 can be discerned in both calorimetric data and in structural data obtained by electron and synchrotron X-ray diffraction (XRD). In contrast, a structural but not an energetic discontinuity is apparent at x [approx equal] 0.65, which corresponds to a compositionally induced [alpha]-[beta] quartz transition with a small enthalpy of transformation. An enthalpy for the Al/Si order-disorder reaction in [beta]-eucryptite was measured as 25.9 [+-] 2.6 kJ/mol. Standard molar enthalpies of formation of the stuffed quartz-derivative phases from constituent oxides ([Delta]H[sub f.ox][sup 0]) and elements ([Delta]H[sub f.el][sup 0]) at 298 K also are presented. [Delta]H[sub f.ox][sup 0] = [minus]69.78 [+-] 1.38 kJ/mol and [Delta]H[sub f.el][sup 0] = [minus]2117.84 [+-] 2.50 kJ/mol for [beta]-eucryptite, which are in good agreement withmore » results previously determined by HF solution calorimetry at 346.7 K (Barany and Adami 1966). The enthalpies of formation of other compositions are reported for the first time.« less

Authors:
; ; ;  [1];  [2]
  1. (Princeton Univ., NJ (United States))
  2. (State Univ. of New York, Stony Brook, NY (United States))
Publication Date:
OSTI Identifier:
6063909
Resource Type:
Journal Article
Journal Name:
American Mineralogist
Additional Journal Information:
Journal Volume: 84:9; Journal ID: ISSN 0003-004X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM OXIDES; CRYSTAL STRUCTURE; FORMATION HEAT; LITHIUM OXIDES; ORDER-DISORDER TRANSFORMATIONS; QUARTZ; SILICON OXIDES; SOLUTION HEAT; ALKALI METAL COMPOUNDS; ALUMINIUM COMPOUNDS; CHALCOGENIDES; ENTHALPY; LITHIUM COMPOUNDS; MINERALS; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PHYSICAL PROPERTIES; REACTION HEAT; SILICON COMPOUNDS; THERMODYNAMIC PROPERTIES; 360606* - Other Materials- Physical Properties- (1992-); 360602 - Other Materials- Structure & Phase Studies

Citation Formats

Xu, H., Heaney, P.J., Navrotsky, A., Topor, L., and Liu, J. Thermochemistry of stuffed quartz-derivative phases along the join LiAlSiO[sub 4]-SiO[sub 2]. United States: N. p., 1999. Web. doi:10.2138/am-1999-0913.
Xu, H., Heaney, P.J., Navrotsky, A., Topor, L., & Liu, J. Thermochemistry of stuffed quartz-derivative phases along the join LiAlSiO[sub 4]-SiO[sub 2]. United States. doi:10.2138/am-1999-0913.
Xu, H., Heaney, P.J., Navrotsky, A., Topor, L., and Liu, J. Wed . "Thermochemistry of stuffed quartz-derivative phases along the join LiAlSiO[sub 4]-SiO[sub 2]". United States. doi:10.2138/am-1999-0913.
@article{osti_6063909,
title = {Thermochemistry of stuffed quartz-derivative phases along the join LiAlSiO[sub 4]-SiO[sub 2]},
author = {Xu, H. and Heaney, P.J. and Navrotsky, A. and Topor, L. and Liu, J.},
abstractNote = {Enthalpies of drop-solution ([Delta]H[sub drop-soln]) of a suite of stuffed quartz-derivative phases with the composition Li[sub 1[minus]x]Al[sub 1[minus]x]Si[sub 1+x]O[sub 4] (0 [le] x [le] 1) have been measured in molten 2PbO[center dot]B[sub 2]O[sub 3] at 974 K. Substitution of Si[sup 4+] for Li[sup +] + Al[sup 3+] results in more exothermic enthalpies of drop-solution, which is consistent with behavior seen in other crystalline and glassy aluminosilicates. Al/Si ordering serves to stabilize these phases, and long-range ordering for compositions with x approximately <0.3 can be discerned in both calorimetric data and in structural data obtained by electron and synchrotron X-ray diffraction (XRD). In contrast, a structural but not an energetic discontinuity is apparent at x [approx equal] 0.65, which corresponds to a compositionally induced [alpha]-[beta] quartz transition with a small enthalpy of transformation. An enthalpy for the Al/Si order-disorder reaction in [beta]-eucryptite was measured as 25.9 [+-] 2.6 kJ/mol. Standard molar enthalpies of formation of the stuffed quartz-derivative phases from constituent oxides ([Delta]H[sub f.ox][sup 0]) and elements ([Delta]H[sub f.el][sup 0]) at 298 K also are presented. [Delta]H[sub f.ox][sup 0] = [minus]69.78 [+-] 1.38 kJ/mol and [Delta]H[sub f.el][sup 0] = [minus]2117.84 [+-] 2.50 kJ/mol for [beta]-eucryptite, which are in good agreement with results previously determined by HF solution calorimetry at 346.7 K (Barany and Adami 1966). The enthalpies of formation of other compositions are reported for the first time.},
doi = {10.2138/am-1999-0913},
journal = {American Mineralogist},
issn = {0003-004X},
number = ,
volume = 84:9,
place = {United States},
year = {1999},
month = {9}
}