Preparation And Characterazition Of Two Kinds Of Amorphous Sulfur By Rapid Compression Method

This paper consists of two parts, in the first part two kinds of amorphous sulfur were synthesized by rapid compression method from liquid sulfur at temperatures below and above λ-transition point. The glassy sulfur adopts different color and transparency depending on the temperature, which are quite consistent with the liquid λ-transition of sulfur. Therefore, we speculate it may inherit some structural information from λ-transition. We analyze the patterns of Raman scattering spectroscopy、 differential scanning calorimetry and X-ray diffraction, and the results showed that:a large fraction of polymeric chains exist in the glassy sulfur, even from the one solidified from T<Tλ. By comparing the content of the polymeric chain of amorphous sulfur under various conditions of pressure and temperature,we found that higher compression rate and larger amplitude of pressure jump instead of higher temperature of parent liquid captured more polymeric chains. The results of the thermal analysis showed that the two kinds of amorphous sulfur both has a high thermal stability,which can avoid crystallization directly into liquid sulfur at the heating rate of lOK/min, and accompanying an abnormal exothermic effect. In summary, we hypothesize that the polymeric chains are formed during rapid compression, and he existent of polymeric chains in both two sets of glassy sulfur suggests that the polymeric chains are not the factor that causes the color distinction. For improving in the great pressure grads of Bridgman anvil apparatus, the Professor Hong Shiming designs a strip opposite anvil instead of conventional round anvil and adopt assortive strip gasket. The second part of this paper is to study pressure calibration of the strip anvil and discuss the uniformity of pressure distribution. Experimental results indicate that the strip opposite anvil with 20mm in length and 5mm in width made of cemented carbide anvil can produce highest pressure may exceed up to 10 GPa and the pressure are almost homogeneous within 12mm along central line. The measuring bias is less than 2.0％in 2.55GPa and 3.6％in 7.7GPa. This feature benefits characterization for linear samples under high pressure.