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Title: Average and Local Crystal Structure of β-Er:Yb:NaYF 4 Upconverting Nanocrystals Probed by X-ray Total Scattering

Authors:
 [1];  [1];  [1]; ORCiD logo [1]
  1. Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NSFUNIVERSITY
OSTI Identifier:
1376244
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials; Journal Volume: 29; Journal Issue: 15
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Perera, S. Sameera, Amarasinghe, Dinesh K., Dissanayake, K. Tauni, and Rabuffetti, Federico A. Average and Local Crystal Structure of β-Er:Yb:NaYF 4 Upconverting Nanocrystals Probed by X-ray Total Scattering. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b01495.
Perera, S. Sameera, Amarasinghe, Dinesh K., Dissanayake, K. Tauni, & Rabuffetti, Federico A. Average and Local Crystal Structure of β-Er:Yb:NaYF 4 Upconverting Nanocrystals Probed by X-ray Total Scattering. United States. doi:10.1021/acs.chemmater.7b01495.
Perera, S. Sameera, Amarasinghe, Dinesh K., Dissanayake, K. Tauni, and Rabuffetti, Federico A. Fri . "Average and Local Crystal Structure of β-Er:Yb:NaYF 4 Upconverting Nanocrystals Probed by X-ray Total Scattering". United States. doi:10.1021/acs.chemmater.7b01495.
@article{osti_1376244,
title = {Average and Local Crystal Structure of β-Er:Yb:NaYF 4 Upconverting Nanocrystals Probed by X-ray Total Scattering},
author = {Perera, S. Sameera and Amarasinghe, Dinesh K. and Dissanayake, K. Tauni and Rabuffetti, Federico A.},
abstractNote = {},
doi = {10.1021/acs.chemmater.7b01495},
journal = {Chemistry of Materials},
number = 15,
volume = 29,
place = {United States},
year = {Fri Jul 21 00:00:00 EDT 2017},
month = {Fri Jul 21 00:00:00 EDT 2017}
}
  • The effect of isovalent chemical substitution on the magnitude and coherence length of local ferroelectric distortions present in sub-20 nm Ba 1–xSr xTiO 3 (x = 0.0, 0.30, 0.50, 1.0) and BaTi 1–yZr yO 3 (y = 0.0, 0.15, 0.50, 1.0) nanocrystals synthesized at room temperature is investigated using X-ray absorption near edge structure (XANES) and pair distribution function analysis of X-ray total scattering data (PDF). Although the average crystal structure of the nanocrystals is adequately described by a centrosymmetric, cubic Pm3¯m space group, local ferroelectric distortions due to the displacement of the titanium atom from the center of themore » perovskite lattice are observed for all compositions, except BaZrO 3. The symmetry of the ferroelectric distortions is adequately described by a tetragonal P4mm space group. The magnitude of the local displacements of the titanium atom in BaTiO 3 nanocrystals is comparable to that observed in single crystals and bulk ceramics, but the coherence length of their ferroelectric coupling is much shorter (≤20 Å). Substitution of Sr 2+ for Ba 2+ and of Zr 4+ for Ti 4+ induces a tetragonal-to-cubic transition of the room temperature local crystal structure, analogous to that observed for single crystals and bulk ceramics at similar compositions. This transition is driven by a reduction of the magnitude of the local displacements of the titanium atom and/or of the coherence length of their ferroelectric coupling. Replacing 50% of Ba 2+ with Sr 2+ slightly reduces the magnitude of the titanium displacement, but the coherence length is not affected. In contrast, replacing 15% of the ferroelectrically active Ti 4+ with Zr 4+ leads to a significant reduction of the coherence length. Deviations from the ideal solid solution behavior are observed in BaTi 1–yZr yO 3 nanocrystals and are attributed to an inhomogeneous distribution of the barium atoms in the nanocrystal. Composition–structure relationships derived for Ba 1–xSr xTiO 3 and BaTi 1–yZr yO 3 nanocrystals demonstrate that the evolution of the room temperature local crystal structure with chemical composition parallels that of single crystals and bulk ceramics, and that chemical control over ferroelectric distortions is possible in the sub-20 nm size range. In addition, the potential of PDF analysis of total scattering data to probe compositional fluctuations in nanocrystals is demonstrated.« less
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  • Local structure of dirubidium tetralithium tris(selenate(VI)) dihydrate - Rb{sub 2}Li{sub 4}(SeO{sub 4}){sub 3}{center_dot} 2H{sub 2}O has been determined basing on the modeling of X-ray diffuse scattering. The origin of observed structured diffuse streaks is SeO{sub 4} tetrahedra switching between two alternative positions in two quasi-planar layers existing in each unit cell and formation of domains with specific SeO{sub 4} tetrahedra configuration locally fulfilling condition for C-centering in the 2a Multiplication-Sign 2b Multiplication-Sign c superstructure cell. The local structure solution is characterized by a uniform distribution of rather large domains (ca. thousand of unit cells) in two layers, but also monodomainsmore » can be taken into account. Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming two-string ribbons. Inside the ribbons SeO{sub 4} and LiO{sub 4} tetrahedra share the oxygen corners, whereas ribbons are bound to each other by a net of hydrogen bonds and fastened by corner sharing SeO{sub 4} tetrahedra of the neighboring layers. - Graphical abstract: Experimental sections of the reciprocal space showing diffraction effects observed for RLSO. Bragg spots are visible on sections with integer indices (1 kl section - on the left), streaks - on sections with fractional ones (1.5 kl section - on the right). At the center: resulting local structure of the A package modeled as a microdomain: two-string ribbons of ordered oxygen-corners-sharing SeO{sub 4} and LiO{sub 4} terahedra extended along ab-diagonal are seen; ribbons are bound by hydrogen bonds (shown in pink); the multiplied 2a Multiplication-Sign 2b unit cell is shown. Highlights: Black-Right-Pointing-Pointer X-ray diffuse scattering in RLSO was registered and modeled. Black-Right-Pointing-Pointer The origin of diffuse streaks is SeO{sub 4} tetrahedra switching in two structure layers. Black-Right-Pointing-Pointer The local structure is characterized by a uniform distribution of microdomains. Black-Right-Pointing-Pointer Inside a single domain SeO{sub 4} tetrahedra are ordered along ab-diagonal forming ribbons. Black-Right-Pointing-Pointer The ribbons are bound to each other by a net of hydrogen bonds.« less
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