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Title: Hydrogen and the structure of transition aluminas

Abstract

{alpha}-Alumina results from the complete dehydration of several minerals of the form Al{sub 2}O{sub 3}{center{underscore}dot}nH{sub 2}O. The ``transition'' aluminas, {gamma}-alumina, {eta}-alumina, and {delta}-alumina are known to have a spinel structure but the possibility that they contain hydrogen (H) has been the subject of debate. The authors present a series of density-functional theory calculations which, together with available experimental data, show that the spinel aluminas exist over a range of hydrogen content captured by the empirical formula H{sub 3m}Al{sub 2{minus}m}O{sub 3}, with a different greek-letter phases corresponding to different distributions of the Aluminum (Al) ions on the two cation sublattices. Calculations of densities and vibrational frequencies of bulk OH bonds are in excellent agreement with available data. The theory reconciles seemingly inconsistent data and reveals a remarkable property of the spinel aluminas: They are ``reactive sponges'' in that they can store and release water in a reactive way. This chemical activity offers a basis for understanding long-standing puzzles in the behavior of aluminas in catalytic systems.

Authors:
; ;
Publication Date:
Research Org.:
Oak Ridge National Laboratory, TN (US)
Sponsoring Org.:
USDOE; National Science Foundation (NSF)
OSTI Identifier:
20000132
DOE Contract Number:  
AC05-96OR22464
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 121; Journal Issue: 33; Other Information: PBD: 25 Aug 1999; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HYDROGEN; ALUMINIUM OXIDES; CRYSTAL STRUCTURE; DEHYDRATION; SPINELS; MATHEMATICAL MODELS

Citation Formats

Sohlberg, K., Pennycook, S.J., and Pantelides, S.T. Hydrogen and the structure of transition aluminas. United States: N. p., 1999. Web. doi:10.1021/ja991098o.
Sohlberg, K., Pennycook, S.J., & Pantelides, S.T. Hydrogen and the structure of transition aluminas. United States. doi:10.1021/ja991098o.
Sohlberg, K., Pennycook, S.J., and Pantelides, S.T. Wed . "Hydrogen and the structure of transition aluminas". United States. doi:10.1021/ja991098o.
@article{osti_20000132,
title = {Hydrogen and the structure of transition aluminas},
author = {Sohlberg, K. and Pennycook, S.J. and Pantelides, S.T.},
abstractNote = {{alpha}-Alumina results from the complete dehydration of several minerals of the form Al{sub 2}O{sub 3}{center{underscore}dot}nH{sub 2}O. The ``transition'' aluminas, {gamma}-alumina, {eta}-alumina, and {delta}-alumina are known to have a spinel structure but the possibility that they contain hydrogen (H) has been the subject of debate. The authors present a series of density-functional theory calculations which, together with available experimental data, show that the spinel aluminas exist over a range of hydrogen content captured by the empirical formula H{sub 3m}Al{sub 2{minus}m}O{sub 3}, with a different greek-letter phases corresponding to different distributions of the Aluminum (Al) ions on the two cation sublattices. Calculations of densities and vibrational frequencies of bulk OH bonds are in excellent agreement with available data. The theory reconciles seemingly inconsistent data and reveals a remarkable property of the spinel aluminas: They are ``reactive sponges'' in that they can store and release water in a reactive way. This chemical activity offers a basis for understanding long-standing puzzles in the behavior of aluminas in catalytic systems.},
doi = {10.1021/ja991098o},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 33,
volume = 121,
place = {United States},
year = {1999},
month = {8}
}