Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study
Densification and sintering of CeO[subscript 2] nanoparticles and their electrical properties were simultaneously studied as a function of temperature in controlled atmosphere using a modified dilatometer. CeO[subscript 2] nanoparticles simultaneously shrink and become more resistive upon initial he...
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| Format: | Article |
| Language: | English |
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Springer US
2016
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| Online Access: | http://hdl.handle.net/1721.1/104938 https://orcid.org/0000-0001-8339-3222 |
| _version_ | 1826204496755163136 |
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| author | Knauth, Philippe Engel, Johanna Bishop, Sean Tuller, Harry L |
| author2 | Massachusetts Institute of Technology. Department of Materials Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Materials Science and Engineering Knauth, Philippe Engel, Johanna Bishop, Sean Tuller, Harry L |
| author_sort | Knauth, Philippe |
| collection | MIT |
| description | Densification and sintering of CeO[subscript 2] nanoparticles and their electrical properties were simultaneously studied as a function of temperature in controlled atmosphere using a modified dilatometer. CeO[subscript 2] nanoparticles simultaneously shrink and become more resistive upon initial heating, associated with desorption of water. The electrical conductance G at 300–550 °C revealed a pO[subscript 2] dependence described by log (G) = A + n × log (pO[subscript 2]) with n ~ −1/6, consistent with n-type conduction. The results were analyzed with a defect equilibrium model based on the reduction of ceria and formation of doubly ionized oxygen vacancies and electrons. The activation energy was found equal to (1.3 ± 0.1) eV, which results in an enthalpy of reduction of (2.7 ± 0.4) eV, considerably lower than that for bulk ceria (~4.5 eV). The coarsening of particles during heat treatment at 800 °C were analysed assuming grain boundary diffusion-limited sintering. Although the coarsened powder shows a similar pO[subscript 2] dependence, the activation energy was considerably higher (1.9 ± 0.1) eV, leading to a reduction enthalpy of (4.5 ± 0.4) eV. The decrease in the enthalpy of reduction with decreasing particle size is consistent with the increasing fraction of oxide ions residing at the surface. Alternate interpretations based on space charge effects and surface adsorption/desorption were considered and found to be less consistent with the experimental results. |
| first_indexed | 2024-09-23T12:56:32Z |
| format | Article |
| id | mit-1721.1/104938 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T12:56:32Z |
| publishDate | 2016 |
| publisher | Springer US |
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| spelling | mit-1721.1/1049382022-10-01T12:03:03Z Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO2—case study Knauth, Philippe Engel, Johanna Bishop, Sean Tuller, Harry L Massachusetts Institute of Technology. Department of Materials Science and Engineering Knauth, Philippe Engel, Johanna Bishop, Sean Tuller, Harry L Densification and sintering of CeO[subscript 2] nanoparticles and their electrical properties were simultaneously studied as a function of temperature in controlled atmosphere using a modified dilatometer. CeO[subscript 2] nanoparticles simultaneously shrink and become more resistive upon initial heating, associated with desorption of water. The electrical conductance G at 300–550 °C revealed a pO[subscript 2] dependence described by log (G) = A + n × log (pO[subscript 2]) with n ~ −1/6, consistent with n-type conduction. The results were analyzed with a defect equilibrium model based on the reduction of ceria and formation of doubly ionized oxygen vacancies and electrons. The activation energy was found equal to (1.3 ± 0.1) eV, which results in an enthalpy of reduction of (2.7 ± 0.4) eV, considerably lower than that for bulk ceria (~4.5 eV). The coarsening of particles during heat treatment at 800 °C were analysed assuming grain boundary diffusion-limited sintering. Although the coarsened powder shows a similar pO[subscript 2] dependence, the activation energy was considerably higher (1.9 ± 0.1) eV, leading to a reduction enthalpy of (4.5 ± 0.4) eV. The decrease in the enthalpy of reduction with decreasing particle size is consistent with the increasing fraction of oxide ions residing at the surface. Alternate interpretations based on space charge effects and surface adsorption/desorption were considered and found to be less consistent with the experimental results. 2016-10-24T15:37:37Z 2016-10-24T15:37:37Z 2014-06 2014-03 2016-08-18T15:43:41Z Article http://purl.org/eprint/type/JournalArticle 1385-3449 1573-8663 http://hdl.handle.net/1721.1/104938 Knauth, P. et al. “Study of Compaction and Sintering of Nanosized Oxide Powders by in Situ Electrical Measurements and Dilatometry: Nano CeO2—case Study.” Journal of Electroceramics 34.1 (2015): 82–90. https://orcid.org/0000-0001-8339-3222 en http://dx.doi.org/10.1007/s10832-014-9946-9 Journal of Electroceramics Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ Springer Science+Business Media New York application/pdf Springer US Springer US |
| spellingShingle | Knauth, Philippe Engel, Johanna Bishop, Sean Tuller, Harry L Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title | Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title_full | Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title_fullStr | Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title_full_unstemmed | Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title_short | Study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry: Nano CeO[subscript 2]—case study |
| title_sort | study of compaction and sintering of nanosized oxide powders by in situ electrical measurements and dilatometry nano ceo subscript 2 case study |
| url | http://hdl.handle.net/1721.1/104938 https://orcid.org/0000-0001-8339-3222 |
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