A recent study published in the journal Nature Physics has shed light on the peculiar properties of water, particularly its ability to exist in two liquid states at extremely low temperatures and high pressure. This phenomenon, known as the “liquid-liquid” critical transition, has puzzled researchers for years.
The unique behavior of water has long been a subject of interest due to its lower density in ice form compared to liquid form, resulting in ice floating on water. Researchers have been intrigued by this unusual characteristic, especially when temperatures drop below -38°C without ice formation.
Previous attempts to observe the transition of water from a state with higher density to a state with lower density under extreme conditions were hindered by the instant crystallization of water, leaving no time for observation. However, through computer modeling, researchers have been able to gain a better understanding of this phenomenon.
Using the MB-Pol model, which considers quantum-chemical interactions in water at a high level of accuracy, researchers were able to simulate the movement of water molecules at a microsecond scale. This modeling revealed sharp density changes at -85°C and a pressure of about 101.3 MPa, confirming the existence of the liquid-liquid transition.
The findings suggest that the transition could occur at around -75°C and a pressure of approximately 126.7 MPa under real conditions. This discovery is significant as it brings experimental verification closer to reality, with the potential for measuring the transition before water crystallizes.
Further research utilizing methods such as neutron scattering, X-ray experiments, and fast spectroscopy will help track the moment of transition between the two liquid phases. Understanding the dual behavior of water not only contributes to fundamental research but also has practical implications ranging from more precise climatic models to advancements in water purification technologies and energy storage.