In-situ observation and analysis of solid-state diffusion and liquid migration in a crystal growth system: A segregation-driven diffusion couple
| Autor: | Didier Perrodin, Kenichi Oikawa, Kerry P. Wang, Sven C. Vogel, Jeffrey J. Derby, Adrian S. Losko, Anton S. Tremsin, Edith Bourret, Takenao Shinohara, Gregory Bizarri, Jeffrey H. Peterson |
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| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Materials science Polymers and Plastics Dopant Neutron imaging Metals and Alloys Crystal growth 02 engineering and technology Scintillator 021001 nanoscience & nanotechnology Thermal diffusivity 01 natural sciences Molecular physics Electronic Optical and Magnetic Materials Atomic diffusion 0103 physical sciences Ceramics and Composites Melting point Neutron 0210 nano-technology |
| Zdroj: | Acta Materialia. 186:434-442 |
| ISSN: | 1359-6454 |
| Popis: | Energy-resolved neutron imaging is employed for in-situ measurements of dopant transport in a simple experiment performed before the crystal growth of the scintillator BaBrCl:5%Eu via a vertical gradient freeze technique. During a stabilization period preceding growth, we observed the diffusion of Eu from the solid phase into the melt over a period of approximately 4 hours. Comparing the measured centerline concentration profile with a mathematical model for the system, we estimate the solid-state diffusivity of Eu in BaBrCl as D 1 = 1.9 × 10 − 10 m2/s and an upper limit for the liquid-phase diffusivity of Eu in the melt as D 2 * = 2.5 × 10 − 10 m2/s, at temperatures near the melting point. We compare this experiment, where diffusion is driven by a concentration discontinuity arising from segregation, to the classical diffusion couple technique. Suggestions are offered on how this segregation-driven couple might be improved as a tool for measuring diffusion coefficients, and we draw attention to the great promise of neutron imaging for in-situ measurements of the distribution of elements, with sufficiently high neutron attenuation coefficients, in difficult environments. |
| Databáze: | OpenAIRE |
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