Structural Changes in Molten Vb and VIb Metals and Ultra-Sound Propagation.

我们用拨款更新了一个门控射频放大器，并建立了一个稳定的超声波测量装置，用它我们系统地测量了各种熔融合金在高温下的声速。为了补充超声波测量，我们用伽马射线衰减法测量了密度。此外，我们还推导出新的热力学关系，使我们能够解释由局部结构变化引起的浓度波动。期间，我们在国际知名期刊上发表了十篇论文。为了继续这个研究项目，我在1998年接受了马赛CNRS的C. Bergman博士和斯图加特MPI的F. Sommer博士的审查。主要结果有：1。as - te体系的结构变化：通过检测声速和/或热膨胀系数作为温度函数的最小值来研究相图。最低时速已确定为60英里。%的a。用外推法确定了过冷熔态As结构变化的过渡点为734±6℃。熔融ⅱb-ⅵb体系的结构变化：通过声速测量表明，熔融CdTe具有非常稳定的结构，而熔融HgTe在熔点附近发生连续的结构变化。确定了熔融HgTe中的过渡点。二元混合物中结构变化与浓度波动的热力学关系：导出了能够解释由局部结构变化引起的浓度波动的新的热力学关系。应用表明了脱毛S-Te体系中环形双熔体相的起源。结构变化引起的浓度波动是制备高质量化合物半导体晶体需要解决的关键问题之一。我们计划通过测量熔融化合物半导体在高温下的比热、声速和密度来系统地研究这一现象。少

We have renewed a gated RF amplifier with the grant and set up a stable ultra-sonic measurement gear, with which we have measured systematically the velocity of sound in various molten alloys at high temperatures. To compliment the ultra-sound measurements, we have measured the density with the gamma-ray attenuation method. Further we have derived the new thermodynamic relations which enable to elucidate the concentration fluctuations induced by local structural changes. During the period of the grand, we have published ten papers in well-established international journals. To proceed the research project, I was reviewed by Dr. C. Bergman at CNRS, Marseille and Dr. F. Sommer at MPI, Stuttgart in 1998.Main results are1. Structural changes in the As-Te system : the phase diagram has been investigated by detecting a minimum in the sound velocity and/or the thermal expansion coefficient as a function of temperature. The minimum has been confirmed up to 60 at.% of As. The transition point i … More n the structural change in the super-cooled molten As has been determined to be 734 ± 6℃ by an extrapolation.2. Structural changes in the molten II b-VI b system : by measuring the sound velocity, it has been shown that the molten CdTe has very stable structure whereas the molten HgTe undergoes continuous structural changes around the melting point. The transition point in the molten HgTe has been determined.3. The thermodynamic relations connecting structural changes and concentration fluctuations in a binary mixture : the new thermodynamic relations which enable to elucidate the concentration fluctuations induced by local structural changes have been derived. Application has been made to show the origin of the looped two-melt phase in the molted S-Te system.The concentration fluctuations induced by structural changes are one of the key points to be clarified to grow high quality crystals of the compound semiconductors. We are planning to investigate systematically the phenomenon by measuring the specific heat as well as the sound velocity and density of molten compound semiconductors at high temperatures. Less