Nonstoichiometry and relative stabilities of Y2Ti2O7 polar surfaces: A density functional theory prediction

Yang, Li; Jiang, Yong; Odette, G.R.; Zhou, Wenchong; Liu, Zuming; Liu, Yong

doi:10.1016/j.actamat.2013.08.031

Cited by 32 publications

(18 citation statements)

References 36 publications

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“…The critical pO2 values for nonstoichiometric-to-stoichiometric transitions are marked as points a and b. Apparently, with increasing pO2, the most energetically favorable interface structure would change from the Y/Ti-rich to stoichiometric and then to the O-rich, following the same trend as seen for the Y2Ti2O7 (100) free surface [55]. But in contrast to the free surface results, the non-stoichiometric interfaces (both Y/Tiand O-rich) dominate here in a much wider range of pO2, leaving an extremely narrow range of pO2 (-28<ln pO2<-26) for preferentially forming a stoichiometric interface.…”

Section: Oxygen Chemical Activity and Interface Phase Diagrammentioning

confidence: 83%

“…Given the OR and the interfacial strains, the stability of an interface structure is dictated by interfacial stoichiometry and interfacial coordination [53,54]. According to our previous study [55], a polar free surface of Y2Ti2O7 may have various possible chemical terminations, or stoichiometry, depending on the oxygen activity (expressed in term of oxygen partial pressure). Similarly, depending on the internal local oxygen activity, one of three typical stoichiometry types is selected on the oxide side of the ferrite/Y2Ti2O7 interface, namely the stoichiometric (labeled as stoi), the non-stoichiometric Y/Ti-rich (ns-2Y2Ti), and the non-stoichiometric O-rich type (ns-5O).…”

Section: Interface Structuresmentioning

confidence: 99%

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The ferrite/oxide interface and helium management in nano-structured ferritic alloys from the first principles

Yang

Jiang

et al. 2016

Acta Materialia

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Nano-size Y-Ti-oxides are largely responsible for the extraordinary mechanical properties and irradiation tolerance of nano-structured ferritic alloys (NFAs). Here we report a theoretical study to assess the characters and possible roles of the ferrite/oxide interface in managing neutron transmutation product helium in NFAs. Using one observed cube-on-cube orientation relationship, various candidate structures of the ferrite/Y2Ti2O7 interfaces were constructed and the associated energies were carefully evaluated. The interface phase diagram is obtained by expressing the energy as a function of temperature and internal oxygen activity (expressed in terms of oxygen partial pressure). The oxide interfaces are predicted to be Y/Ti-rich at thermodynamic equilibrium for the wide temperature range of interest. Vacancy formation energies are lower and helium segregates to the interfaces, in preference to the iron matrix and grain boundaries. Combined with our previous results on bulk-phase Y2Ti2O7, the profound implications of nano-oxides to helium management in NFAs are discussed.

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Section: Oxygen Chemical Activity and Interface Phase Diagrammentioning

confidence: 83%

Section: Interface Structuresmentioning

confidence: 99%

The ferrite/oxide interface and helium management in nano-structured ferritic alloys from the first principles

Yang

Jiang

et al. 2016

Acta Materialia

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“…Note, interface vacancies in the iron may provide better lattice matching. The stoichiometry of the oxide termination surfaces has a large effect on their energies, 39 and it is expected that this, along with misfit strains and structural defects, will mediate the oxidematrix interface as well.…”

Section: Character Of the Nfsmentioning

confidence: 99%

Recent Progress in Developing and Qualifying Nanostructured Ferritic Alloys for Advanced Fission and Fusion Applications

Odette

2014

JOM

168

110

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This article summarizes the recent progress on developing a class of potentially transformational structural materials called nanostructured ferritic alloys, which are leading candidates for advanced fission and fusion energy applications. Here, we focus on Fe-Cr-based ferritic stainless steels containing a very high concentration of Y-Ti-O nano-oxide features that enable a host of outstanding high-temperature properties, along with unique irradiation tolerance and thermal stability. Perhaps most notably, these alloys have an unprecedented capability to manage very high helium concentrations, pertinent to fusion service, in a way that transforms this element from a severe liability to a potential asset. In addition to providing some necessary background, we update progress on: (I) the character of the nanofeatures; (II) some unifying insights on key mechanical properties; (III) a quantitative model for nanofeature coarsening; (IV) recent irradiation experiments of the effects of helium on cavity evolution and void swelling; and (V) a powerful new mechanism controlling the transport, fate, and consequences of helium.

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“…These nano-particles are distinguished by their high stability and resistance to coarsening even at high temperature and, thus, have attracted considerable interest in the materials research community. Previous studies suggested that these nano-particles range from coherent solute-enriched clusters (1-3 nm in diameter) to non-and or near-stoichiometric complex oxide (more than 3 nm in diameter) [2]. Concerning the near-stoichiometric oxide particles, it is now well established that their structure matches with the Y 2 Ti 2 O 7 structure [2,3] or with the Y 2 TiO 5 structure [2], although they present a stoichiometry gap [4].…”

Section: Introductionmentioning

confidence: 96%

“…Previous studies suggested that these nano-particles range from coherent solute-enriched clusters (1-3 nm in diameter) to non-and or near-stoichiometric complex oxide (more than 3 nm in diameter) [2]. Concerning the near-stoichiometric oxide particles, it is now well established that their structure matches with the Y 2 Ti 2 O 7 structure [2,3] or with the Y 2 TiO 5 structure [2], although they present a stoichiometry gap [4]. However, these nano-particles are not of interest for this paper, only the solute-enriched clusters called nanoclusters hereafter are worthwhile.…”

Section: Introductionmentioning

confidence: 99%

Radiation-sustained nanocluster metastability in oxide dispersion strengthened materials

Ribis

Bordas

Trocellier

et al. 2015

Nuclear Instruments and Methods in Physics Research Section B:

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Nonstoichiometry and relative stabilities of Y2Ti2O7 polar surfaces: A density functional theory prediction

Cited by 32 publications

References 36 publications

The ferrite/oxide interface and helium management in nano-structured ferritic alloys from the first principles

The ferrite/oxide interface and helium management in nano-structured ferritic alloys from the first principles

Recent Progress in Developing and Qualifying Nanostructured Ferritic Alloys for Advanced Fission and Fusion Applications

Radiation-sustained nanocluster metastability in oxide dispersion strengthened materials

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