Generation of negative pressure through Berthelot method and measurements of properties of super-expanded liquid states under negative pressure

金属管贝特洛法是一种热力学方法，通过温度循环，首先加热，然后在适当的温度范围内冷却系统，为密封在金属管中的液体产生负压。我们过去的工作集中在一种调节方法上，通过这种方法，将单晶钼管中的水和有机物的负压提高到150巴。不幸的是，管子慢慢地被腐蚀了。1)通过对CMSX-4镍基高温合金单晶管进行预脱气，并在9次脱气水的温度循环运行后，获得了-120 bar左右的负压。2)将PMPEB液晶密封在管中，在不同的样品密度密封条件下测量其压力与温度的关系。结果表明：2-1)绘制了该向列相液晶的P-T相图；2-2)在负压下观察到其各向同性的液-向列相转变；2-3)多晶性，即发现熔点分别为37.41和46℃的三种晶型；2-4)两种晶型之间的一级相变。大多数Berthelot方法数据与我们在1 bar下完成的DSC数据一致。这些结果表明贝特洛特方法适用于研究有机物热力学性质在正负压范围内的压力依赖性。特别是，结果2-2)对发展有机超膨胀凝聚相热力学具有重要意义。我们还表明，3)Berthelot方法可以检测到在金属管中与液体密封在一起的固体的10^<-7> cc量级的微小体积变化。硅、介孔硅酸盐和吸附在介孔中的气体分子在水中的溶解被检测为填充温度的降低，其中填充温度是贝特洛系统的特征温度，在该温度下，管道的整个体积在加热过程中完全被冷凝相所占据。少

Metal tube Berthelot method is a thermodynamic means for generating negative pressure for a liquid sealed in a metal tube by a temperature cycle, first heating and subsequent cooling of the system over an appropriate temperature range. Our past work has been concentrated on a conditioning approach by which negative pressure is raised to-150 bar for water and organics in a single-crystalline Mo tube. Unfortunately, the tube was corroded slowly.In the present work we investigate 1)CMSX-4,Ni-based super-alloy single crystalline tube has achieved negative pressure of the order of-120 bar by pre-degassing the tube, and after runs of temperature cycles with 9 times refreshing of de-aerated water.2)A liquid crystal, PMPEB, is sealed in the tube and its pressure versus temperature relations are measured at various sample-density sealing conditions. The results are 2-1)P-T phase diagram of this nematic liquid crystal is drawn, 2-2)its isotropic liquid-nematic phase transition is observed under … More negative pressure, 2-3)poly-morphism, that is, three crystalline forms having melting points of 37.41, and 46℃, respectively, are found and 2-4)a first-order phase transition between two of the crystals. Most of the Berthelot method data are consistent with our DSC data done at 1 bar.These results demonstrate that Bethelot method is applicable to investigate pressure dependence of thermodynamic properties of organics from positive to negative pressure ranges. In particular, the result 2-2)is of importance in development of thermodynamics of super-expanded condensed phases of organics.We also show that 3)Berthelot method can detect small volume changes of the order of 10^<-7> cc of solids that are sealed together with a liquid in the metal tube. Dissolutions of Si, mesoporous silicate, and adsorbed gas molecules in the mesopores into water are detected as lowerings of temperature of filling, where the temperature of filling is a characteristic temperature of a Berthelot system at which the whole volume of the tube is completely occupied by the condensed phases alone during its heating. Less