Solid-State Reactive Sintering of Transparent Polycrystalline Nd:YAG Ceramics |
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| Authors: | Sang-Ho Lee Sujarinee Kochawattana Gary L. Messing John Q. Dumm Gregory Quarles Vida Castillo |
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| Affiliation: | Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802; II–VI Incorporated, Saxonburg, Pennsylvania 16056; VLOC Inc., Subsidiary of II–VI Inc., New Port Richey, Florida 34655 |
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| Abstract: | Transparent polycrystalline Nd:YAG ceramics were fabricated by solid-state reactive sintering a mixture of commercial Al2O3, Y2O3, and Nd2O3 powders. The powders were mixed in methanol and doped with 0.5 wt% tetraethoxysilane (TEOS), dried, and pressed. Pressed samples were sintered from 1700° to 1850°C in vacuum without calcination. Transparent fully dense samples with average grain sizes of ∼50 μm were obtained at 1800°C for all Nd2O3 levels studied (0, 1, 3, and 5 at.%). The sintering temperature was little affected by Nd concentration, but SiO2 doping lowered the sintering temperature by ∼100°C. Abnormal grain growth was frequently observed in samples sintered at 1850°C. The Nd concentration was determined by energy-dispersive spectroscopy to be uniform throughout the samples. The in-line transmittance was >80% in the 350–900 nm range regardless of the Nd concentration. The best 1 at.% Nd:YAG ceramics (2 mm thick) achieved 84% transmittance, which is equivalent to 0.9 at.% Nd:YAG single crystals grown by the Czochralski method. |
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