https://scholars.lib.ntu.edu.tw/handle/123456789/155473
標題: | Distribution of oxidation states of Cr ions in Ca or Ca/Mg co-doped Cr:Y 3Al 5O 12 single-crystal fibers with nitrogen or oxygen annealing environments | 作者: | Tsai, Cheng-Nan Huang, Kuang-Yao Tsai, Hann-Jong Chen, Jian-Cheng SHENG-LUNG HUANG Lin Y.-S. |
關鍵字: | A1. Doping; A1. Optical microscopy; A2. Laser heated pedestal growth | 公開日期: | 2008 | 卷: | 310 | 期: | 11 | 起(迄)頁: | 2774-2779 | 來源出版物: | Journal of Crystal Growth | 摘要: | The valence states of Cr ions in Ca or Ca/Mg co-doped Cr:Y3Al5O12 (YAG) single-crystal fibers are studied. The fibers were grown using the laser-heated pedestal growth method, followed by annealing treatments up to 1500 °C. The concentrations of the Cr3+ and Cr4+ ions in octahedral and tetrahedral sites in oxygen or nitrogen environments were characterized. Above 700 °C, migration of Cr4+ between octahedral and tetrahedral sites takes place; its relative stabilization energy was estimated. For Ca,Cr:YAG annealed in an oxygen or nitrogen environment, it was 0.25 and 0.3 eV, respectively. For Mg,Ca,Cr:YAG annealed in oxygen or nitrogen, it was 0.47 and 0.49 eV, respectively. For the Ca,Cr:YAG crystal fiber (Ca/Cr=113.1%) with oxygen annealing, about 35% and 2.5% of Ca ions took part in charge compensation for Cr4+ in the octahedral and tetrahedral sites, respectively. The density of oxygen vacancies depends on the concentration of Ca ions. The estimated ratios of the unreacted oxygen vacancies to total oxygen vacancies were about 63% and 88% for oxygen and nitrogen annealing, respectively. The main limitation on the concentration of Cr4+ in the tetrahedral site of YAG is the presence of unreacted oxygen vacancies. © 2008 Elsevier B.V. All rights reserved. |
URI: | http://www.scopus.com/inward/record.url?eid=2-s2.0-42749090712&partnerID=MN8TOARS http://scholars.lib.ntu.edu.tw/handle/123456789/340798 http://ntur.lib.ntu.edu.tw/bitstream/246246/144199/1/06.pdf |
ISSN: | 00220248 | DOI: | 10.1016/j.jcrysgro.2008.02.028 | SDG/關鍵字: | Annealing; Laser heating; Nitrogen; Optical microscopy; Oxidation; Oxygen vacancies; Laser heated pedestal growth; Nitrogen environments; Valence states; Single crystals |
顯示於: | 電機工程學系 |
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