Hydrogen Isotope Absorption in Unary Oxides and Nitrides with Anion Vacancies and Substitution.
Chemphyschem
; 20(10): 1369-1375, 2019 05 16.
Article
em En
| MEDLINE
| ID: mdl-30681760
ABSTRACT
The absorption states of hydrogen isotopes in various ceramic materials were investigated by density functional theory. For pristine ceramic materials, main-group oxides do not form any bond with a hydrogen atom. However, transition metal oxides form hydroxyl groups and absorb hydrogen atoms. Main-group and transition metal nitrides form ionic bonds between a hydrogen atom and the surrounded cation. For anion-deficient ceramic materials, hydrogen atoms are negatively charged because of excess electrons induced by anion vacancies, and ionic bonds form with the surrounded cation, which stabilizes the hydrogen absorption state. N substitutional doping into oxides introduces an electron hole, while O substitutional doping into the nitrides introduces an excess of electrons. Therefore, hydrogen isotopes form covalent bonds in N-substituted oxides, and form hydride ions in O-substituted nitrides. Thus, Al2 O3 , SiO2 , CrN, and TiN are promising materials as hydrogen permeation barriers.
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Chemphyschem
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2019
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Article