In-situ observation of phase transformations in layered perovskite BaEu2Mn2O7

Nakano, Hiromi; Ishizawa, Nobuo; Kamegashira, Naoki

doi:10.1016/j.jeurceramsoc.2009.05.011

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…Although, in real materials, the ionic ordering could be in between those two ideal cases, this assumption still works well to qualitatively predict the A-site ionic ordering in terms of A and A′ ionic size. Figure plots t̅ and Δ r of various A 2 A′B 2 O 7 systems with reported P 4 2 / mnm (T′), I 4/ mmm , Acaa , A 2 1 am , Fmmm , and Pnma phases, clearly showing that all T′ data points tend to cluster within the dashed orange boundary, whereas all other phases are outside. − Ca 2 SrRu 2 O 7 is the only exception, which is probably because it is the only metallic material among all compounds in the statistics. From the plot, Δ r ≥ 14 pm is essential to stabilize T′ phases.…”

Section: Resultsmentioning

confidence: 96%

Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration

Huang

Admasu

et al. 2022

Chem. Mater.

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The bilayer perovskites' family A 3 B 2 O 7 holds rich structural complexity. When magnetism freedom is added in, great opportunities appear for new physics. Magnetic Tb ions in Tb 2 SrAl 2 O 7 are known to crystallize in a bilayer square lattice. The results of our comprehensive neutron, X-ray diffraction, and transmission electron microscopy (TEM) experiments reveal a crystallographic P4 2 /mnm symmetry accompanied with roomtemperature topological type-II Z 8 vortex domains, whose density is controllable by cooling rates, as described by the Kibble−Zurek mechanism. The DC magnetic susceptibility without long-range order down to 1.8 K suggests frustrated magnetism, while a spin freezing <2.5 K is observed in the AC susceptibility, which is likely due to the antisite disorder and another possible cause of no longrange ordering. Strong temperature evolution of magnetic anisotropy indicates an interplay of low-lying crystal electric field levels and anisotropic exchange interactions. Our results suggest that Tb 2 SrAl 2 O 7 is a promising candidate of magnetic frustration in a bilayer square lattice, and this system can be a new playground for exploring exotic magnetic states in bilayer square lattices, topological magnetic edge states at coherent crystallographic domain walls, and multifunctional applications.

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Section: Resultsmentioning

confidence: 96%

Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration

Huang

Admasu

et al. 2022

Chem. Mater.

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“…Recently, we also observed the multiple phase transition in-situ in BaEu 2 Mn 2 O 7 . 46) In the future, we are going to clarify more systematically such issues as in-situ phase transition from liquid-N 2 temperature to high temperature in order to understand the nature of manganite with the layered perovskite structure.…”

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confidence: 99%

Microstructural evolution by in-situ TEM observations of oxides

Nakano

2011

J. Ceram. Soc. Japan

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In-situ observations using high-temperature transmission electron microscopy (TEM) is a promising technique for obtaining new findings and developing phenomenological theory for ceramic materials at high temperatures. By observing the changes in hydrothermal BaTiO 3 due to heating, we clarify the vanishing mechanism of internal pores and the mechanism of BaCO 3 phase generation/vanishing at high temperatures. Through observations of the grain growth of BaTiO 3 prepared by radio-frequency plasma chemical vapor deposition, we calculate the grain-boundary diffusion coefficient, which is an important parameter controlling the sinterability of ceramics. Observations of the shrinkage and disappearance of Ba 5 Nb 4 O 15 , as well as simulations, indicate that high energy and low diffusivity at the grain boundary make grains vanish while maintaining a truncated spherical shape. Finally, observations of the structural changes in layered perovskite BaLn 2 Mn 2 O 7 (Ln = Gd, Pr, Eu) reveal a first-order phase transition that has not been previously reported.

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Octahedral rotations in Ruddlesden-Popper layered oxides under pressure from first principles

Ramkumar

Nowadnick

2021

Phys. Rev. B

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In-situ observation of phase transformations in layered perovskite BaEu2Mn2O7

Cited by 3 publications

References 11 publications

Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration

Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration

Microstructural evolution by in-situ TEM observations of oxides

Octahedral rotations in Ruddlesden-Popper layered oxides under pressure from first principles

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In-situ observation of phase transformations in layered perovskite BaEu2Mn2O7

Cited by 3 publications

References 11 publications

Bilayer Square Lattice Tb2SrAl2O7 with Structural Z8 Vortices and Magnetic Frustration

Bilayer Square Lattice Tb2SrAl2O7 with Structural Z8 Vortices and Magnetic Frustration

Microstructural evolution by in-situ TEM observations of oxides

Octahedral rotations in Ruddlesden-Popper layered oxides under pressure from first principles

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Product

Resources

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Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration

Bilayer Square Lattice Tb₂SrAl₂O₇ with Structural Z₈ Vortices and Magnetic Frustration