| Autor: |
Venkatraman Gopalan, Gary L. Messing, John Q. Dumm, Sujarinee Kochawattana, Mariola O. Ramírez, Adam J. Stevenson, Vida K. Castillo, Gregory J. Quarles, Sang Ho Lee |
| Rok vydání: |
2008 |
| Předmět: |
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| Zdroj: |
Journal of the European Ceramic Society. 28:1527-1534 |
| ISSN: |
0955-2219 |
| DOI: |
10.1016/j.jeurceramsoc.2007.12.006 |
| Popis: |
Densification and grain growth in pure YAG, SiO 2 doped YAG and SiO 2 doped Nd:YAG were explored. The activation energy for densification (235 kJ/mol) in pure YAG is lower than that of grain growth (946 kJ/mol) which is unusual in ceramic systems. Consequently, pure YAG sinters to near full density (>99.9%) at 1700 °C with little grain growth (1.2 μm average grain size). The remaining large pores (radius > 2 μm) were determined to be thermodynamically stable because their coordination number with grains was >6. The stability of these pores underscores the importance of powder processing and forming in fabricating transparent YAG. SiO 2 doped YAG sinters to near full density 100 °C lower than pure YAG because SiO 2 enables liquid phase sintering and the removal of large pores. The addition of Nd 2 O 3 further enhances both densification and grain growth at temperatures below 1700 °C. Above 1700 °C higher concentrations of Nd 3+ suppressed grain growth, possibly due to solute drag. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect