| Surface behaviour and undercooling in the liquid Ga—Bi binary system detected by optical second harmonic generation |
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| 引用本文： | 王聪,王天民.Surface behaviour and undercooling in the liquid Ga—Bi binary system detected by optical second harmonic generation[J].中国物理 B,2003,12(3):315-321. |
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| 作者姓名： | 王聪 王天民 |
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| 作者单位： | Centre of Material Physics and Chemistry, School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083, China |
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| 基金项目： | Project supported by the Alexander von Humboldt (AvH) foundation, Germany. |
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| 摘 要： | We employ an optical second harmonic generation(SHG) technique to investigate the surface behaviours at the liquid(solid)/vapour interface of the Ga-Bi binary metallic system. In a heating and cooling cycle between 280℃ and room temperature, there is no change of the SH-intensity in the heating process, whereas there exists an abrupt and abnormal change of the SH-intensity in the cooling process. It is interesting to find that a macroscopic Bi-rich solid layer is floating on the surface of the Ga-rich liquid phase just below the monotectic temperature (222℃±2℃) in the cooling process, in spite of the Bi-rich phase being heavier than the Ga-rich phase. On the other hand, different undercooling behaviours are observed at the surface and in the bulk. The behaviours of surface solidification and surface melting are different from those in the bulk.
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| 关 键 词： | 表面物理学 液态Ga－Bi复合系统 表面 |
| 收稿时间： | 2002-05-27 |
Surface behaviour and undercooling in the liquid Ga-Bi binary system detected by optical second harmonic generation |
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| Wang Cong and Wang Tian-Min.Surface behaviour and undercooling in the liquid Ga-Bi binary system detected by optical second harmonic generation[J].Chinese Physics B,2003,12(3):315-321. |
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| Authors: | Wang Cong and Wang Tian-Min |
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| Institution: | Centre of Material Physics and Chemistry, School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083, China |
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| Abstract: | We employ an optical second harmonic generation(SHG) technique to investigate the surface behaviours at the liquid(solid)/vapour interface of the Ga-Bi binary metallic system. In a heating and cooling cycle between 280℃ and room temperature, there is no change of the SH-intensity in the heating process, whereas there exists an abrupt and abnormal change of the SH-intensity in the cooling process. It is interesting to find that a macroscopic Bi-rich solid layer is floating on the surface of the Ga-rich liquid phase just below the monotectic temperature (222℃±2℃) in the cooling process, in spite of the Bi-rich phase being heavier than the Ga-rich phase. On the other hand, different undercooling behaviours are observed at the surface and in the bulk. The behaviours of surface solidification and surface melting are different from those in the bulk. |
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| Keywords: | surface phase transition second harmonic generation liquid(solid)/vapour interface Ga-Bi binary alloy undercooling |
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