Schuster, Beatrice (2011)
Oxide ceramics under extreme pressure and radiation conditions.
Buch, Erstveröffentlichung
Kurzbeschreibung (Abstract)
This experimental study tackles the question how oxide ceramics (ZrO$_2$ and HfO$_2$) respond to the simultaneous exposure to two extreme conditions, pressures up to several ten GPa and irradiation with highly energetic (MeV-GeV) heavy ion projectiles. The combination of these two extreme conditions influences the materials in ways none of those two conditions alone could.\\ In both materials, the exposure to high-fluence irradiations at ambient pressure result in a crystalline-to-crystalline phase transformation from the monoclinic into the first high temperature tetragonal phase. For heavy ions such as Xe, Au, Pb, and U this structural change requires a double impact process. For light ions such as Ni and Cr, the transferred energy does not suffice to induce any transformation indicating an energy loss threshold in ZrO$_2$ as well as in HfO$_2$. If the irradiation is performed under high pressure, the monoclinic-to-tetragonal transformation occurs already at a fluence that is more than one order of magnitude lower, suggesting a single-hit process. Although the ZrO$_2$ and HfO$_2$ behave much alike as no two other compound materials, their response to the combination of pressure and ion irradiation differs. X-ray diffraction analysis of the irradiated, pressurized samples and Raman and TEM measurements at ambient conditions revealed that the monoclinic-to-tetragonal transformation in ZrO$_2$ around 10 GPa is not direct but includes a detour into the cubic high-temperature phase, before the tetragonal structure becomes stable under decompression. For HfO$_2$, high fluence irradiation at 10 GPa results in the intensification of the first high pressure phase which is afterwards stabilized to ambient conditions. At higher pressures, additional ion irradiation forces both ceramics to perform a transition into their second high pressure phase (orthorhombic-II) far away from its stability field. This study demonstrates that the combination of ion irradiation and high pressure can serve as a trigger for transitions into different phases and as stabilization mechanism of usually unstable structures.
| Typ des Eintrags: | Buch | ||||
|---|---|---|---|---|---|
| Erschienen: | 2011 | ||||
| Autor(en): | Schuster, Beatrice | ||||
| Art des Eintrags: | Erstveröffentlichung | ||||
| Titel: | Oxide ceramics under extreme pressure and radiation conditions | ||||
| Sprache: | Englisch | ||||
| Referenten: | Fujara, Prof. Franz | ||||
| Publikationsjahr: | 14 Juni 2011 | ||||
| Ort: | Darmstadt | ||||
| Verlag: | TU Darmstadt | ||||
| Datum der mündlichen Prüfung: | Juli 2011 | ||||
| URL / URN: | urn:nbn:de:tuda-tuprints-27533 | ||||
| Kurzbeschreibung (Abstract): | This experimental study tackles the question how oxide ceramics (ZrO$_2$ and HfO$_2$) respond to the simultaneous exposure to two extreme conditions, pressures up to several ten GPa and irradiation with highly energetic (MeV-GeV) heavy ion projectiles. The combination of these two extreme conditions influences the materials in ways none of those two conditions alone could.\\ In both materials, the exposure to high-fluence irradiations at ambient pressure result in a crystalline-to-crystalline phase transformation from the monoclinic into the first high temperature tetragonal phase. For heavy ions such as Xe, Au, Pb, and U this structural change requires a double impact process. For light ions such as Ni and Cr, the transferred energy does not suffice to induce any transformation indicating an energy loss threshold in ZrO$_2$ as well as in HfO$_2$. If the irradiation is performed under high pressure, the monoclinic-to-tetragonal transformation occurs already at a fluence that is more than one order of magnitude lower, suggesting a single-hit process. Although the ZrO$_2$ and HfO$_2$ behave much alike as no two other compound materials, their response to the combination of pressure and ion irradiation differs. X-ray diffraction analysis of the irradiated, pressurized samples and Raman and TEM measurements at ambient conditions revealed that the monoclinic-to-tetragonal transformation in ZrO$_2$ around 10 GPa is not direct but includes a detour into the cubic high-temperature phase, before the tetragonal structure becomes stable under decompression. For HfO$_2$, high fluence irradiation at 10 GPa results in the intensification of the first high pressure phase which is afterwards stabilized to ambient conditions. At higher pressures, additional ion irradiation forces both ceramics to perform a transition into their second high pressure phase (orthorhombic-II) far away from its stability field. This study demonstrates that the combination of ion irradiation and high pressure can serve as a trigger for transitions into different phases and as stabilization mechanism of usually unstable structures. |
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| Zusätzliche Informationen: | Darmstadt, TU, Diss., 2011 |
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| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 530 Physik | ||||
| Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) |
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| Hinterlegungsdatum: | 13 Sep 2011 11:11 | ||||
| Letzte Änderung: | 05 Mär 2013 09:54 | ||||
| PPN: | |||||
| Referenten: | Fujara, Prof. Franz | ||||
| Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | Juli 2011 | ||||
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