Thermophysical Property Measurements of Non-Equilibrium Melts

高温液态硅的热输运性质，如等压摩尔热容、半球总发射率和热导率，是提高直拉法制备高质量单晶硅数值模拟的关键参数。然而，由于接触材料污染和对流的存在，高温液态硅的热输运特性很难测量。为了克服这些问题，一个非接触式调制激光量热法在静磁场中发展的等压摩尔热容，半球总发射率和液态硅的热导率的同时测量。在1750 ~ 2050 K温度范围内，在0.5 ~ 4 T静磁场中，测量了液态硅的等压摩尔热容和半球总发射率。通过施加静磁场，有效地抑制了电磁悬浮硅液滴中的对流。在1750 K和2050 K之间的温度下，通过施加2 T或更大的静磁场并抑制对流来测量热导率。测定的热导率表明，在1750-2050 K温度范围内，电子对液态硅中的热输运起主导作用。

Thermal transport properties of high temperature liquid silicon such as isobaric molar heat capacity, hemispherical total emissivity and thermal conductivity, are key parameter for improving the numerical modeling to produce high quality of single crystalline silicon by Czochralski method. However, it is difficult to measure the thermal transport properties of high-temperature liquid silicon due to the existing of both contamination from contact material and convections. To overcome these problems, a noncontact modulated laser calorimetry in a static magnetic field was developed for simultaneous measurement of the isobaric molar heat capacity, the hemispherical total emissivity and the thermal conductivity of liquid silicon. The isobaric molar heat capacity and the hemispherical total emissivity of liquid silicon were measured at temperature between 1750 K and 2050 K in a static magnetic field from 0.5 to 4 T. The convections in the electromagnetically levitated liquid silicon droplet were effectively suppressed by imposing a static magnetic field. The thermal conductivity was measured at temperatures between 1750 K and 2050 K by imposing the static magnetic field at 2 T or larger with suppressed convections. The determined thermal conductivity shows that the electron contribution is dominant for thermal transport in liquid silicon at temperatures of 1750-2050 K.