Computational studies of cation and anion ordering in cubic yttria stabilized zirconia
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2007
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| Online Access: | http://hdl.handle.net/1721.1/36208 |
| _version_ | 1811070756034969600 |
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| author | Predith, Ashley P. (Ashley Page) |
| author2 | Gerbrand Ceder. |
| author_facet | Gerbrand Ceder. Predith, Ashley P. (Ashley Page) |
| author_sort | Predith, Ashley P. (Ashley Page) |
| collection | MIT |
| description | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006. |
| first_indexed | 2024-09-23T08:41:04Z |
| format | Thesis |
| id | mit-1721.1/36208 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T08:41:04Z |
| publishDate | 2007 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/362082019-04-09T19:12:58Z Computational studies of cation and anion ordering in cubic yttria stabilized zirconia Predith, Ashley P. (Ashley Page) Gerbrand Ceder. Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Materials Science and Engineering. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006. Includes bibliographical references (p. 127-137). The investigation of ordering and phase stability in the ZrO2-Y203 system involves two sets of calculations. The first set of calculations uses the cluster expansion method. A guide to the practical implementation of the cluster expansion outlines methods for defining a goal and choosing structures and clusters that best model the system of interest. The cluster expansion of the yttria stabilized zirconia system considers 447 configurations across the ZrO2-Y203 composition range. The effective cluster interaction for pair clusters show electrostatic repulsion between anions and little interaction between cations. Triplet anion terms largely modify the energy contributions of the pair terms. Separate cluster expansions using structures at single compositions show that cation clusters become more important at high yttria composition. The cluster expansion led to the discovery of three previously unidentified ordered ground state structures at 25, 29, and 33 % Y on the cubic fluorite lattice. The ground state with 33 % Y is stable with respect to the calculated energies of monoclinic ZrO2 and the Y4Zr3012 ground state. The ground states have the common ordering feature of yttrium and vacancies in [1 1 2] chains, and Monte Carlo simulations show that vacancy ordering upon cooling is contingent on cation ordering. (cont.) The second set of calculations consider three driving forces for order: ionic relaxation, vacancy arrangements, and differences in Zr and cation dopant radii. Bond valence sums of fully relaxed and anion relaxed structures are nearly equal at all compositions. In supercells of ZrO2, the vacancy arrangement of the ground state with 25 % Y is more stable than arrangements maximizing the distance between vacancies or aligning vacancies in [1 1 1]. Comparing the YSZ ground state with structures of the same configuration with scandium replacing yttrium shows different stable phases on the convex hull between cubic ZrO2 and the dopant M203 phase. The change in the stability of the configurations may be a result of cation radius sizes. The factors suggest that the driving forces of phase stability depend on composition. by Ashley P. Predith. Ph.D. 2007-02-21T13:05:50Z 2007-02-21T13:05:50Z 2006 2006 Thesis http://hdl.handle.net/1721.1/36208 76905148 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 137 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Materials Science and Engineering. Predith, Ashley P. (Ashley Page) Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title | Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title_full | Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title_fullStr | Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title_full_unstemmed | Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title_short | Computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| title_sort | computational studies of cation and anion ordering in cubic yttria stabilized zirconia |
| topic | Materials Science and Engineering. |
| url | http://hdl.handle.net/1721.1/36208 |
| work_keys_str_mv | AT predithashleypashleypage computationalstudiesofcationandanionorderingincubicyttriastabilizedzirconia |