2D‐HARECXS analysis of dopant and oxygen vacancy sites in Al‐doped yttrium titanate

A Y2Ti2O7/Al2O3 multilayer, exhibiting high thermal reflectivity and oxidation resistivity, holds potential as a functional surface coating for advanced gas turbine blades. Slight Al doping of Y2Ti2O7 has been found to significantly improve the structural stability of the multilayer, the detailed me...

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Bibliographic Details
Published inJournal of the American Ceramic Society Vol. 104; no. 7; pp. 3760 - 3769
Main Authors Ohtsuka, Masahiro, Oda, Kenji, Tanaka, Makoto, Kitaoka, Satoshi, Muto, Shunsuke
Format Journal Article
LanguageEnglish
Published Columbus Wiley Subscription Services, Inc 01.07.2021
Subjects
Aluminum oxide
Angular resolution
Channeling
Dopants
dopants/doping
Electron beams
electron microscopy
Fluorescence
Functional materials
Gas turbine engines
Jet engines
Multilayers
Oxidation
Oxygen
Regression analysis
spectroscopy
Statistical analysis
Structural stability
Thermodynamic properties
transmission
Turbine blades
Two dimensional analysis
Vacancies
Yttrium
yttrium/yttrium compounds
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Summary:A Y2Ti2O7/Al2O3 multilayer, exhibiting high thermal reflectivity and oxidation resistivity, holds potential as a functional surface coating for advanced gas turbine blades. Slight Al doping of Y2Ti2O7 has been found to significantly improve the structural stability of the multilayer, the detailed mechanism of which remains unclear. Hence, we examined the site occupancies of doped Al using high‐angular resolution electron channeling X‐ray spectroscopy with two‐dimensional rocking of the incident electron beam. A statistical linear regression analysis of a set of observed ionization channeling patterns (ICPs) of fluorescent X‐rays quantitatively confirmed that Al3+ preferentially occupied the Ti4+ site, rather than the Y3+ site, because of the large difference in the ionic radii of Al3+ and Y3+. Furthermore, the comparison of theoretical and experimental X‐ray ICPs showed that oxygen vacancies VO were introduced at the 48f site, the first‐nearest neighbor of the Ti site, which was consistent with the hypothesis that oxygen vacancies compensate for the local charge imbalance associated with preferential substitution of Al3+ for Ti4+. Our findings can aid in improving the thermal properties of environmental barrier coatings applied to advanced jet engines and also demonstrate the utility of beam‐rocking schemes for investigating dopant effects in various functional materials.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.17764