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Title: Influence of F Content on the Composition of Al-Rich Synthetic Phlogopite: Part II. Probing

Abstract

The influence of F substitution on the local structure of Al in the tetrahedral and octahedral sheets

Authors:
 [1];  [2];  [2];  [3];  [3];  [4];  [4]
  1. (EMSL FACILITY USERS)
  2. (Hanover College)
  3. (8998)
  4. (University of British Columbia)
Publication Date:
Research Org.:
Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Lab. (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
15005605
DOE Contract Number:
AC06-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Mineralogist; Journal Volume: 88; Journal Issue: 7; Other Information: PBD: 1 Jul 2003
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FLUORINE; CATALYTIC EFFECTS; ALUMINIUM COMPOUNDS; CRYSTAL STRUCTURE; ENVIRONMENTAL MOLECULAR SCIENCES LABORATORY, CORRECTIONS TO TITLE: CAPITALIZATION STANDARDS JW 11/20/03

Citation Formats

Fechtelkord, Michael F., Behrens, Harald, Holtz, Francois, Bretherton, Jeremy L., Fyfe, Colin A., Groat, Lee A., and Raudsepp, Mati. Influence of F Content on the Composition of Al-Rich Synthetic Phlogopite: Part II. Probing. United States: N. p., 2003. Web. doi:10.2138/am-2003-0713.
Fechtelkord, Michael F., Behrens, Harald, Holtz, Francois, Bretherton, Jeremy L., Fyfe, Colin A., Groat, Lee A., & Raudsepp, Mati. Influence of F Content on the Composition of Al-Rich Synthetic Phlogopite: Part II. Probing. United States. doi:10.2138/am-2003-0713.
Fechtelkord, Michael F., Behrens, Harald, Holtz, Francois, Bretherton, Jeremy L., Fyfe, Colin A., Groat, Lee A., and Raudsepp, Mati. Tue . "Influence of F Content on the Composition of Al-Rich Synthetic Phlogopite: Part II. Probing". United States. doi:10.2138/am-2003-0713.
@article{osti_15005605,
title = {Influence of F Content on the Composition of Al-Rich Synthetic Phlogopite: Part II. Probing},
author = {Fechtelkord, Michael F. and Behrens, Harald and Holtz, Francois and Bretherton, Jeremy L. and Fyfe, Colin A. and Groat, Lee A. and Raudsepp, Mati},
abstractNote = {The influence of F substitution on the local structure of Al in the tetrahedral and octahedral sheets},
doi = {10.2138/am-2003-0713},
journal = {American Mineralogist},
number = 7,
volume = 88,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 2003},
month = {Tue Jul 01 00:00:00 EDT 2003}
}
  • A combination of physicochemical methods has been used in studying the formation of structure and phase composition of the MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ system, depending on the molybdenum content. Three forms have been established for the states of the active component, and concentration limits have been determined for the formation of these states under the conditions of synthesis.
  • Enthalpies of solution of synthetic magnesium aluminum phlogopite samples K(Mg[sub 3[minus]x]Al[sub x])(Al[sub 1+x]Si[sub 3[minus]x])O[sub 10](OH)[sub 2] with 0.00 [le] X[sub East] [le] 0.92 were measured in molten 2PbO-B[sub 2]O[sub 3] at 977 K. The enthalpy of mixing for the phlogopite-eastonite join is large, asymmetric, and endothermic. The solid solution is destabilized more by [sup [6]]Mg,[sup [4]]Si substitution into eastonite than by [sup [6]]Al,[sup [4]]Al substitution into phlogopite, reflecting the increased strain in the mica structure at high [sup [6,4]]Al content that arises from increased lateral misfit between the smaller octahedral and larger tetrahedral sheets. The entropy of mixing has beenmore » calculated assuming a random distribution of Mg and Al on one octahedral site and a short-range ordered distribution of Al and Si on four tetrahedral sites. The calculated activity-composition relations predict a large region of immiscibility up to [approximately] 1,500 K that is consistent with observed limits of [sup [6,4]]Al substitution in naturally occurring Fe-poor phlogopite. The thermodynamic data for phlogopite and eastonite are assessed using the metastable reaction Phl + 3 Qtz = San + 3 En + H[sub 2]O, in which the breakdown of magnesium aluminum phlogopite also produces spinel. A standard enthalpy of formation of phlogopite from the elements at 298 K of [minus]6215.0 [plus minus] 3.5 kJ/mol is consistent with both data from high-temperature solution calorimetry and results from phase equilibria experiments. The standard enthalpy of formation of eastonite from the elements at 298 K is between [minus]6352 and [minus]6363 kJ/mol; the large uncertainty arises from estimating the heat capacity of eastonite. The P,T stability of phlogopite increases with increasing [sup [6,4]]Al content., 7 figs., 5 tabs.« less
  • IR spectroscopy has been used in determining the sources of the deactivating effect of CO and O/sub 2/ in the reaction of NO reduction by carbon monoxide in the presence of oxygen on Pd/..gamma..-Al/sub 2/O/sub 3/. IR spectra were taken with separate and joint chemisorption of NO and CO, and also directly under the conditions of the reaction, with a ratio m = ((NO) + 2(O/sub 2/))/(CO) from 0.69 to 1.62. The observed nitrosyl and carbonyl complexes are stabilized on Pd in different degrees of oxidation. The lower NO conversions in mixtures with excess CO are explained by competitive adsorptionmore » of NO and CO. With increasing concentration of O/sub 2/ up to 0.3% by volume (m = 1.15), the degree of oxidation of the Pd increases. Along with this, there is a decrease in the bond strength in Pd-CO complexes, and favorable conditions are created for chemisorption and activation of NO molecules. The lower NO conversions when m > 1.15 are due to further oxidation of the palladium, on which, apparently, dissociative chemisorption of NO is suppressed. Formation conditions and properties are examined for -NCO surface isocyanate complexes localized on the support and -NCO and -CN complexes that are presumably bound to the active components.« less
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