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Title: Microstructural characterization of terbium-doped ceria

Abstract

The microstructures of Ce{sub 1-x}Tb {sub x}O{sub 2-{delta}} (0.10 {<=} x {<=} 0.50) sintered samples were studied systematically using transmission electron microscopy. The sintered samples consist of not only fluorite-structured matrix but also nano-sized precipitates. Correspondingly, diffuse scattering and extra reflections related to the precipitates were observed in the selected area diffraction patterns. The composition of the precipitates was studied quantitatively by electron energy-loss spectroscopy, indicating that the precipitates have higher Tb concentration than that of the matrix. Furthermore, Tb{sup 3+} and Ce{sup 3+} cations were observed to segregate in the precipitates.

Authors:
 [1];  [2];  [2];  [3];  [4];  [5]
  1. Fuel Cell Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan). E-mail: fei.ye@nims.go.jp
  2. Fuel Cell Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)
  3. School of Engineering, University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia)
  4. (Australia)
  5. Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Brisbane, Queensland 4072 (Australia)
Publication Date:
OSTI Identifier:
21000640
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 42; Journal Issue: 5; Other Information: DOI: 10.1016/j.materresbull.2006.08.007; PII: S0025-5408(06)00327-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERIUM IONS; CERIUM OXIDES; DIFFUSE SCATTERING; DOPED MATERIALS; ENERGY-LOSS SPECTROSCOPY; FLUORITE; MICROSTRUCTURE; NANOSTRUCTURES; OPTICAL REFLECTION; PRECIPITATION; TERBIUM; TERBIUM IONS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Ye, F., Mori, Toshiyuki, Ou, D.R., Zou Jin, Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072, and Drennan, John. Microstructural characterization of terbium-doped ceria. United States: N. p., 2007. Web. doi:10.1016/j.materresbull.2006.08.007.
Ye, F., Mori, Toshiyuki, Ou, D.R., Zou Jin, Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072, & Drennan, John. Microstructural characterization of terbium-doped ceria. United States. doi:10.1016/j.materresbull.2006.08.007.
Ye, F., Mori, Toshiyuki, Ou, D.R., Zou Jin, Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072, and Drennan, John. Thu . "Microstructural characterization of terbium-doped ceria". United States. doi:10.1016/j.materresbull.2006.08.007.
@article{osti_21000640,
title = {Microstructural characterization of terbium-doped ceria},
author = {Ye, F. and Mori, Toshiyuki and Ou, D.R. and Zou Jin and Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, Queensland 4072 and Drennan, John},
abstractNote = {The microstructures of Ce{sub 1-x}Tb {sub x}O{sub 2-{delta}} (0.10 {<=} x {<=} 0.50) sintered samples were studied systematically using transmission electron microscopy. The sintered samples consist of not only fluorite-structured matrix but also nano-sized precipitates. Correspondingly, diffuse scattering and extra reflections related to the precipitates were observed in the selected area diffraction patterns. The composition of the precipitates was studied quantitatively by electron energy-loss spectroscopy, indicating that the precipitates have higher Tb concentration than that of the matrix. Furthermore, Tb{sup 3+} and Ce{sup 3+} cations were observed to segregate in the precipitates.},
doi = {10.1016/j.materresbull.2006.08.007},
journal = {Materials Research Bulletin},
number = 5,
volume = 42,
place = {United States},
year = {Thu May 03 00:00:00 EDT 2007},
month = {Thu May 03 00:00:00 EDT 2007}
}
  • Anisotropic sintered magnets based on the Nd{sub 2}Fe{sub 14}B phase doped with Tb were prepared using a grain-boundary diffusion process (GBDP) in order to enhance their coercivity. A FEGSEM microstructural analysis revealed that these GBDP magnets had a core-shell structure, where thin, Tb-rich, (NdTb){sub 2}Fe{sub 14}B shells are formed on the original matrix Nd{sub 2}Fe{sub 14}B grains after diffusion of the Tb. This shell thickness varies from a few tens of nanometres in the middle of the magnet up to a few micrometers near the edge. The exact chemical composition of these shells was determined using EDS and WDS electron-probemore » microanalyses, which were modified and optimized for submicrometer scale analyses. When analyzing the common Nd-L{alpha}, Tb-L{alpha} and Fe-K{alpha} lines a mutual multiple overlap in the EDS spectra is present and, as a result, an accurate quantitative analysis was only feasible when using WDS. Using this technique we were able to achieve a lateral analytical resolution of 0.4 {mu}m. A further improvement in resolution, down to 0.15 {mu}m, was realized with a dedicated set-up using low-voltage EDS, analyzing the 'atypical' low-energy Nd-M{alpha}, Tb-M{alpha} and Fe-L{alpha} lines. Quantitative analyses confirmed that the reaction phase (Nd{sub x}Tb{sub 1} {sub -x}){sub 2}Fe{sub 14}B is formed after the diffusion of Tb with the equilibrium concentration of Tb being equal to x Almost-Equal-To 0.5, i.e., with the atomic ratio of Nd/Tb equal to 1/1. We also found that a relatively sharp Tb concentration gradient from the shell to the core occurs within a length of Almost-Equal-To 0.5 {mu}m, while the Fe concentration remains unchanged. In terms of magnetic properties, the Tb-doping significantly increased coercivity by Almost-Equal-To 30% while the remanence remained at the same value as in the undoped Nd-Fe-B. - Highlights: Black-Right-Pointing-Pointer Nd-Fe-B sintered magnets were doped with Tb using grain-boundary diffusion process. Black-Right-Pointing-Pointer A tiny core-shell reaction phase was formed around the Nd{sub 2}Fe{sub 14}B matrix grains. Black-Right-Pointing-Pointer EDS and WDS analyses confirmed (Nd{sub 0.5}Tb{sub 0.5}){sub 2}Fe{sub 14}B equilibrium shell composition. Black-Right-Pointing-Pointer Coercivity of Tb-doped Nd-Fe-B increases by 30% without a drop in remanence.« less
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  • Highly-oriented pure and gadolinia-doped ceria thin films have been grown on pure and ZrO2 (111)-buffered Al2O3 (0001) substrates using oxygen plasma-assisted molecular beam epitaxy (OPA-MBE) to understand the oxygen ionic transport processes in ceria based oxide thin films. Gadolinia-doped ceria films grown on pure Al2O3(0001) substrate show polycrystalline features due to structural deformations resulting from the large lattice mismatch between the Al2O3(0001) substrate and the films. However, the films, grown on a thin layer of ZrO2(111) buffered Al2O3 (0001) substrate, appears to be highly oriented. These films were characterized using high resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopymore » (XPS) depth profiling. Oxygen ionic conductivity in gadolinia-doped ceria films was measured as a function of Gd concentration and these results were compared with the ion conductance data of the polycrystalline and single crystalline yttria-stabilized zirconia (YSZ).« less
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