Filters

20212

More filters

20222
Reset filters

Settings

search.filters.applied.f.access: openAccess × End date: 2024 × Start date: 2020 × Subject: Diffraction peaks × WGL Institute: IKZ ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Epitaxial stannate pyrochlore thin films: Limitations of cation stoichiometry and electron doping
    (Melville, NY : AIP Publishing, 2021) Hensling, Felix V. E.; Dahliah, Diana; Dulal, Prabin; Singleton, Patrick; Sun, Jiaxin; Schubert, Jürgen; Paik, Hanjong; Subedi, Indra; Subedi, Biwas; Rignanese, Gian-Marco; Podraza, Nikolas J.; Hautier, Geoffroy; Schlom, Darrell G.
    We have studied the growth of epitaxial films of stannate pyrochlores with a general formula A2Sn2O7 (A = La and Y) and find that it is possible to incorporate ∼25% excess of the A-site constituent; in contrast, any tin excess is expelled. We unravel the defect chemistry, allowing for the incorporation of excess A-site species and the mechanism behind the tin expulsion. An A-site surplus is manifested by a shift in the film diffraction peaks, and the expulsion of tin is apparent from the surface morphology of the film. In an attempt to increase La2Sn2O7 conductivity through n-type doping, substantial quantities of tin have been substituted by antimony while maintaining good film quality. The sample remained insulating as explained by first-principles computations, showing that both the oxygen vacancy and antimony-on-tin substitutional defects are deep. Similar conclusions are drawn on Y2Sn2O7. An alternative n-type dopant, fluorine on oxygen, is shallow according to computations and more likely to lead to electrical conductivity. The bandgaps of stoichiometric La2Sn2O7 and Y2Sn2O7 films were determined by spectroscopic ellipsometry to be 4.2 eV and 4.48 eV, respectively. © 2021 Author(s).
  • Thumbnail Image
    Item
    Reciprocal space slicing: A time-efficient approach to femtosecond x-ray diffraction
    (Melville, NY : AIP Publishing LLC, 2021) Zeuschner, S.P.; Mattern, M.; Pudell, J.-E.; von Reppert, A.; Rössle, M.; Leitenberger, W.; Schwarzkopf, J.; Boschker, J.E.; Herzog, M.; Bargheer, M.
    An experimental technique that allows faster assessment of out-of-plane strain dynamics of thin film heterostructures via x-ray diffraction is presented. In contrast to conventional high-speed reciprocal space-mapping setups, our approach reduces the measurement time drastically due to a fixed measurement geometry with a position-sensitive detector. This means that neither the incident (ω) nor the exit ( 2θ ) diffraction angle is scanned during the strain assessment via x-ray diffraction. Shifts of diffraction peaks on the fixed x-ray area detector originate from an out-of-plane strain within the sample. Quantitative strain assessment requires the determination of a factor relating the observed shift to the change in the reciprocal lattice vector. The factor depends only on the widths of the peak along certain directions in reciprocal space, the diffraction angle of the studied reflection, and the resolution of the instrumental setup. We provide a full theoretical explanation and exemplify the concept with picosecond strain dynamics of a thin layer of NbO2.