Thermal processing conditions for the synthesis of near theoretical density Li5La3Ta2O12 ceramics for ceramic dual-mode detectors
| Autor: | Ching-Fong Chen, Kurt E. Sickafus, Claudia J. Rawn, Joshua Paul Smith, Charles L. Melcher, Cordell Delzer |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Mechanical Engineering Metals and Alloys Analytical chemistry Sintering 02 engineering and technology Radioluminescence 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Tantalate Lattice constant Mechanics of Materials Impurity Phase (matter) visual_art Materials Chemistry visual_art.visual_art_medium Photoluminescence excitation Ceramic 0210 nano-technology |
| Zdroj: | Journal of Alloys and Compounds. 872:159714 |
| ISSN: | 0925-8388 |
| Popis: | A family of Li-containing garnet compounds, extensively investigated for Li-ion solid electrolyte applications, show great potential to be developed into transparent ceramic dual-mode scintillators. In particular, Li5La3Ta2O12 (LLTaO) shows promise as an efficient dual-mode scintillator due to its high Li content, high density, non-hygroscopicity, and high effective-Z. Often the synthesis of LLTaO ceramics involves solid state processing techniques starting with oxide and carbonate powders, calcining, sintering for the removal of residual porosity, and post-processing. This study focuses on two objectives: (1) establishing thermal processing boundary conditions for a flexible alkoxide-based sol-gel method for synthesizing fine-grained powders; and (2), consolidating powders via hot-pressing to form high-density ceramics. In this study, near single-phase ceramics were achieved by hot-pressing sol-gel powders with varying amounts of excess Li. Rietveld refinements were used to analyze X-ray diffraction data and provide a quantitative evaluation of the phases present in the hot pressed ceramics. Some of the diffraction data showed large low angle peak asymmetry, suggesting the presence of two cubic Li5La3Ta2O12 garnet phases with different lattice parameters. Depending on the synthesis and processing conditions, the refinement revealed ~ 90 wt% concentration of a phase with a ≈ 12.8 A and ~ 10 wt% concentration of a phase with a ≈ 12.9 A, indicating a remaining excess of Li in the hot pressed ceramics in the large lattice parameter phase. These synthesis experiments allowed for the determination of a baseline for Li loss during hot-pressing. X-ray excited radioluminescence and photoluminescence excitation and emission spectra were obtained from the hot pressed ceramics. The measured emission spectra featured broad tantalate emission and line emissions likely from a rare-earth impurity. |
| Databáze: | OpenAIRE |
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