Study on the Structural Relaxation in Supercooled Liquids and Glasses

本项目研究了过冷液体态和玻璃态的结构弛豫。选择氯化物和氧化物的玻璃形成体系作为研究对象。对含氯化锌的二元体系进行了超声光谱分析。在这些二元熔体中，在过冷温度区发现了声波的色散。对ZnCl_2- nacl、ZnCl_2- kcl和ZnCl_2- ZnCl_2- cscl二元熔体进行了瑞利-布里渊散射实验。在550 ~ 1000K的温度范围内，得到了每个二元熔体的瑞利-布里渊光谱的完整轮廓。光谱形状随温度和成分的变化而发生的显著变化已被观察到，并已得出结论，这是由于熔体中的结构松弛所致。在高超声速区域的熔体中观察到声波传播的色散。用粘弹性理论，在单松弛假设下对其谱进行了分析。测定了弛豫时间和极限低频、极限高频速度随温度和氯碱组分的变化规律。对玻璃态也进行了实验。用纯ZnCl_2、ZnCl_2- kbr和ZnCl_2- ki样品制备了玻璃样品。在玻璃态得到的光谱与在过冷液体中的光谱相似。在玻璃态下，在GHz频段内没有结构弛豫。

The structural relaxation in the super cooled liquid and glass states has been studied in present project. The glass forming systems of chlorides and oxides has been selected as the objects. Ultrsonic spectroscopy has been carried out in binary systems containing zinc chloride. In those binary melts, the dispersion of sound wave has been found in the super cooled temperature region.Rayleigh-Brillouin scattering experiment has been carried out for ZnCl_2-NaCl, ZnCl_2-KCl and ZnCl_2 ZnCl_2-CsCl binary melts. The complete profiles of Rayleigh-Brillouin spectra were obtained for each binary melt, and at temperatures ranging from 550 to 1000K.The remarkable change in the shape of the spectrum with the variations in temperature and composition has been observed and has been concluded to be due to a structural relaxation in the melts. A dispersion of sound wave propagation was observed in the melts at the hypersonic region. The spectra have been analyzed by the viscoelastic theory with the assumption of the single relaxation. The relaxation time and the velocities at limiting low frequency and high frequency were determined as functions of temperature and of alkali chloride composition.The experiment has also been done for glass state. The samples of pure ZnCl_2, ZnCl_2-KBr and ZnCl_2-KI has been used for preparing glass samlpes. The spectra obtained in glass state was similar to those in super cooled liquids. In the glass state there was not structural relaxation in the frequency region of GHz.