Understanding the difference in bulk modulus between Y-doped SrCeO3 and Y-doped SrZrO3 by ultrasonic transmission method and density functional theory

Fujisaki, Takaya; Hinata, Keisuke; Iguchi, Fumitada; Dimov, Nikolay; Staykov, Aleksandar; Matsumoto, Hiroshige

doi:10.1016/j.mtla.2022.101616

Cited by 1 publication

(1 citation statement)

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“…Bond stiffnesses are expected to influence the tendencies for bond elongation and bond angle changes, but consistent trends between elastic moduli and hydration CCE are not evident in this work. Bulk moduli for BZY (140 GPa) and SZY (152 GPa) are significantly higher than the values for BCY (105 GPa) and SCY (115 GPa), , yet the latter two have the lowest and highest CCEs of these compositions, respectively. However, the minimal B–O bond length changes for SZY may be due to the high bond strength between Zr and O.…”

Section: Discussionmentioning

confidence: 72%

Tuning Perovskites’ Hydration-Induced Chemical Expansion with Octahedral Tilt Angles

Anderson,

Zhang,

Perry

2024

Chem. Mater.

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Hydration-induced strains in proton-conducting oxides compromise chemo-mechanical stability when these materials are applied in protonic ceramic electrochemical cells. To develop design principles for zero-strain materials, we systematically studied the hydration coefficients of chemical expansion (CCEs) in perovskite (Sr, Ba)(Ce, Zr, Y)O 3−x solid solutions with in situ dilatometry and thermogravimetric analysis in the range of 430−630 °C. By including and decoupling a wide range of tolerance factors and lattice parameters, we were able to identify a minimum in hydration CCEs (0−0.02) at intermediate tolerance factor values (t ≈ 0.95). Conversely, despite expectations of lower CCEs in larger unit cells, no general trend in CCE versus lattice parameter was found, and opposite trends could be seen for Sr(Ce, Zr, Y)O 3−x versus Ba(Ce, Zr, Y)O 3−x separately. In situ neutron diffraction (ND) enabled atomistic insight. Upon decreasing t, chemical strain anisotropy increased, but this trend did not match the U-shaped dependence of macroscopic CCEs on t. Instead, perovskites with intermediate t, hosting intermediate octahedral tilt angles in the nominally dry state, underwent the largest change in the B−O−B angles during hydration. Accommodating hydration through decreasing B−O−B angles is beneficial because it does not result in large lattice parameter changes. We propose an intermediate tolerance factor as a simple structural descriptor to enable near-zero hydration strains in proton-conducting perovskites.

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Section: Discussionmentioning

confidence: 72%