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Updated: Sep 18, 2025
Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
Isovalent yet Dissimilar B-Site Occupants in Y2M2O7 Pyrochlore: Repercussions on Structure, Optical Properties, and
Santosh K Sahu1, Rakesh Shukla1,2, Reshmi T Parayil2,3
1Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Abstract:
Effective immobilization of nuclear waste requires advanced ceramics like pyrochlore (A2B2O7) that can accommodate diverse ions present in waste streams over long periods of time under extreme conditions. While A-/B-site substitutions are well-studied, the impact of an isovalent yet dissimilar ion at the B-site on the structure, electronic environment, and response to extreme conditions remains underexplored. This study investigates Ge4+ incorporation in Y2Ti2O7 (YTO), motivated by its distinct coordination preference compared to Ti4+. A systematic analysis is conducted on variations in the bulk structure (XRD), anionic sublattice (Raman), local polyhedral changes (XAS), and A-site effects (Eu3+-PL). Despite favorable features, only 30 mol % Ge could substitute in YTO beyond which the anionic sublattice distorts to accommodate the cation's preference for 4-fold coordination, ultimately leading to phase separation. Eu3+ emission confirms A-site polyhedral distortion upon the B-site modification. No phase transitions were observed until 1200 °C and both lattice and bulk thermal expansion coefficients decreased with Ge content. Gamma irradiation (up to 1000 kGy) left the lattice intact, but swift heavy-ion (100 MeV I) exposure induced partial amorphization, with greater damage in Ge-containing YTO. These comprehensive investigations into structural stability and extreme condition response offer valuable insights for designing effective nuclear waste immobilization materials.
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