Chessboard/diamond nanostructures and the a -site deficient, Li1/2-3x Nd1/2+xTiO3, defect perovskite solid solution

Ray Withers, Laure Nelly Bourgeois, Amanda Snashall, Yun Liu, Lasse Noren, Christian Dwyer, Joanne Etheridge

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The crystal chemical origin of nanoscale chessboard/diamond ordering in perovskite-related solid solutions of composition Li0.5–3xNd0.5+xTiO3 (LNT, x ∼ 0.02–0.12) is investigated. Experimental and simulated scanning transmission electron microscopy (STEM) images are found to be consistent with the compositional modulation model proposed by previous authors. However, these earlier models do not satisfactorily explain other features observed in high-resolution STEM and TEM images, such as the two-dimensional {100} lattice fringes with the same periodicity, √2ap × √2ap, as the local LNT unit cell viewed along the [001] direction (where ap is the parent perovskite unit cell parameter). Based on bond valence sum calculations, we propose a new set of crystal structures for LNT in which Li ions are primarily bonded to only two O ions, and order one-dimensionally with √2ap periodicity. Bright-field STEM image simulations performed for this new model reproduced the experimentally observed √2ap lattice fringes, thus strongly suggesting that the finer features of the high-resolution (S)TEM images are the result of Li ion ordering and associated local structural relaxation. In this new model, the LNT chessboard supercell then results from the ordered combinations of two sublattices: the Li ion sublattice and its translational variants on the one hand, and the Nd0.5TiO3 sublattice and its oxygen octahedral tilt twin variants on the other. Dielectric measurements indicate the presence of long-lived polar clusters that are easily activated under an applied electric field. This suggests that these clusters consist of spatially correlated Li ions.
Original languageEnglish
Pages (from-to)190 - 201
Number of pages12
JournalChemistry of Materials
Volume25
Issue number2
DOIs
Publication statusPublished - 2013

Cite this

Withers, Ray ; Bourgeois, Laure Nelly ; Snashall, Amanda ; Liu, Yun ; Noren, Lasse ; Dwyer, Christian ; Etheridge, Joanne. / Chessboard/diamond nanostructures and the a -site deficient, Li1/2-3x Nd1/2+xTiO3, defect perovskite solid solution. In: Chemistry of Materials. 2013 ; Vol. 25, No. 2. pp. 190 - 201.
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title = "Chessboard/diamond nanostructures and the a -site deficient, Li1/2-3x Nd1/2+xTiO3, defect perovskite solid solution",
abstract = "The crystal chemical origin of nanoscale chessboard/diamond ordering in perovskite-related solid solutions of composition Li0.5–3xNd0.5+xTiO3 (LNT, x ∼ 0.02–0.12) is investigated. Experimental and simulated scanning transmission electron microscopy (STEM) images are found to be consistent with the compositional modulation model proposed by previous authors. However, these earlier models do not satisfactorily explain other features observed in high-resolution STEM and TEM images, such as the two-dimensional {100} lattice fringes with the same periodicity, √2ap × √2ap, as the local LNT unit cell viewed along the [001] direction (where ap is the parent perovskite unit cell parameter). Based on bond valence sum calculations, we propose a new set of crystal structures for LNT in which Li ions are primarily bonded to only two O ions, and order one-dimensionally with √2ap periodicity. Bright-field STEM image simulations performed for this new model reproduced the experimentally observed √2ap lattice fringes, thus strongly suggesting that the finer features of the high-resolution (S)TEM images are the result of Li ion ordering and associated local structural relaxation. In this new model, the LNT chessboard supercell then results from the ordered combinations of two sublattices: the Li ion sublattice and its translational variants on the one hand, and the Nd0.5TiO3 sublattice and its oxygen octahedral tilt twin variants on the other. Dielectric measurements indicate the presence of long-lived polar clusters that are easily activated under an applied electric field. This suggests that these clusters consist of spatially correlated Li ions.",
author = "Ray Withers and Bourgeois, {Laure Nelly} and Amanda Snashall and Yun Liu and Lasse Noren and Christian Dwyer and Joanne Etheridge",
year = "2013",
doi = "10.1021/cm303239d",
language = "English",
volume = "25",
pages = "190 -- 201",
journal = "Chemistry of Materials",
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Chessboard/diamond nanostructures and the a -site deficient, Li1/2-3x Nd1/2+xTiO3, defect perovskite solid solution. / Withers, Ray; Bourgeois, Laure Nelly; Snashall, Amanda; Liu, Yun; Noren, Lasse; Dwyer, Christian; Etheridge, Joanne.

In: Chemistry of Materials, Vol. 25, No. 2, 2013, p. 190 - 201.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Chessboard/diamond nanostructures and the a -site deficient, Li1/2-3x Nd1/2+xTiO3, defect perovskite solid solution

AU - Withers, Ray

AU - Bourgeois, Laure Nelly

AU - Snashall, Amanda

AU - Liu, Yun

AU - Noren, Lasse

AU - Dwyer, Christian

AU - Etheridge, Joanne

PY - 2013

Y1 - 2013

N2 - The crystal chemical origin of nanoscale chessboard/diamond ordering in perovskite-related solid solutions of composition Li0.5–3xNd0.5+xTiO3 (LNT, x ∼ 0.02–0.12) is investigated. Experimental and simulated scanning transmission electron microscopy (STEM) images are found to be consistent with the compositional modulation model proposed by previous authors. However, these earlier models do not satisfactorily explain other features observed in high-resolution STEM and TEM images, such as the two-dimensional {100} lattice fringes with the same periodicity, √2ap × √2ap, as the local LNT unit cell viewed along the [001] direction (where ap is the parent perovskite unit cell parameter). Based on bond valence sum calculations, we propose a new set of crystal structures for LNT in which Li ions are primarily bonded to only two O ions, and order one-dimensionally with √2ap periodicity. Bright-field STEM image simulations performed for this new model reproduced the experimentally observed √2ap lattice fringes, thus strongly suggesting that the finer features of the high-resolution (S)TEM images are the result of Li ion ordering and associated local structural relaxation. In this new model, the LNT chessboard supercell then results from the ordered combinations of two sublattices: the Li ion sublattice and its translational variants on the one hand, and the Nd0.5TiO3 sublattice and its oxygen octahedral tilt twin variants on the other. Dielectric measurements indicate the presence of long-lived polar clusters that are easily activated under an applied electric field. This suggests that these clusters consist of spatially correlated Li ions.

AB - The crystal chemical origin of nanoscale chessboard/diamond ordering in perovskite-related solid solutions of composition Li0.5–3xNd0.5+xTiO3 (LNT, x ∼ 0.02–0.12) is investigated. Experimental and simulated scanning transmission electron microscopy (STEM) images are found to be consistent with the compositional modulation model proposed by previous authors. However, these earlier models do not satisfactorily explain other features observed in high-resolution STEM and TEM images, such as the two-dimensional {100} lattice fringes with the same periodicity, √2ap × √2ap, as the local LNT unit cell viewed along the [001] direction (where ap is the parent perovskite unit cell parameter). Based on bond valence sum calculations, we propose a new set of crystal structures for LNT in which Li ions are primarily bonded to only two O ions, and order one-dimensionally with √2ap periodicity. Bright-field STEM image simulations performed for this new model reproduced the experimentally observed √2ap lattice fringes, thus strongly suggesting that the finer features of the high-resolution (S)TEM images are the result of Li ion ordering and associated local structural relaxation. In this new model, the LNT chessboard supercell then results from the ordered combinations of two sublattices: the Li ion sublattice and its translational variants on the one hand, and the Nd0.5TiO3 sublattice and its oxygen octahedral tilt twin variants on the other. Dielectric measurements indicate the presence of long-lived polar clusters that are easily activated under an applied electric field. This suggests that these clusters consist of spatially correlated Li ions.

UR - http://pubs.acs.org/doi/abs/10.1021/cm303239d

U2 - 10.1021/cm303239d

DO - 10.1021/cm303239d

M3 - Article

VL - 25

SP - 190

EP - 201

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 2

ER -