Making temperature-pressure contour map of sound wave relaxation strength of liquid water - toward verification of liquid-liquid phase transition scenario

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03789
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
• Research Institution: Hiroshima University
• Principal Investigator: Kajihara Yukio 広島大学, 先進理工系科学研究科(総), 助教 (20402654)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 液体－液体相転移 / 水の熱力学異常 / 臨界ゆらぎ / 緩和現象 / 音波

Outline of Final Research Achievements

Contour map of the sound wave relaxation strength (temperature and pressure dependence) for liquid water over a wide temperature and pressure range up to 500 C and 10000 bar were made. Two significant mountain/hill-like enhancements were observed, which are almost consistent with the contour map of the isochoric specific heat, suggesting that the specific heat originate from the sound wave relaxation phenomenon. We conclude that the origins of the two enhancements in the high-temperature region is due to critical fluctuation of the liquid-gas phase transition, and that in the low-temperature region near ambient conditions is due to critical fluctuation corresponding to the liquid-liquid phase transition, which is believed to exist in the supercooled region.

Free Research Field

不規則系物理学

Academic Significance and Societal Importance of the Research Achievements

水は最もありふれた液体ですが、熱力学特性は他とはかなり異なる「異常液体」で、未だそのメカニズムは十分には分かっていません。今回の研究では比熱の起源が初めて実験的に特定できており、非常に価値のあるものです。今後水あるいは水溶液などの熱力学特性の理解が進み、様々な方面への応用が期待できます。また学術的には、液体－液体相転移という新しいタイプの相転移について、既知の液体－気体相転移との類似点と相違点を整理して議論しており、今後相転移論の進展が期待できます。