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

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 15540391
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biophysics/Chemical physics
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: OHDE Yoshihito Nagoya Institute of Technology, Graduate School of Engineering, Assistant Professor, 工学研究科, 助教授 (10024340)
• Co-Investigator(Kenkyū-buntansha): TANZAWA Yasutoshi Nagoya Institute of Technology, Graduate School of Engineering, Assistant Professor, 工学研究科, 助教授 (60236776)
• Project Period (FY): 2003 – 2004
• Keywords: Berthelot method / negative pressure / P-T phase diagram / super-expanded / thermobarometry / liquid crystal / DSC / nematic

Research Abstract

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 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.