Researchers identify fundamental property of how water, other liquids move at different temperatures

Jan 14, 2011 By David L. Chandler

In a finding that has been met with surprise and some controversy in the scientific community, researchers at MIT and elsewhere have discovered a basic property that governs the way water and many other liquids behave as their temperature changes.

Liquids have long been known to exhibit a rapid change in properties near a point called the glass , where the viscosity of the liquid — its “thickness,” or resistance to flow — becomes very large. But MIT professor Sow-Hsin Chen and his co-researchers have found a different transition point at a temperature about 20 to 30 percent higher, which they call the dynamic crossover temperature. This temperature may be at least as important as the glass transition temperature, and the viscosity at the dynamic crossover temperature seems to have a universal value for a large class of (called glass-forming liquids) that includes such familiar substances as water, ammonia and benzene.

At this new transition temperature, “all the transport properties of the liquid state change drastically,” Chen says. “Nobody realized this universal property of liquids before.” The work, carried out by physics professor Francesco Mallamace of the University of Messina, Italy (who is a research affiliate at MIT) and four of his students from Messina, along with Chen, an MIT professor emeritus of nuclear science and engineering, and Eugene Stanley, a physics professor at Boston University, was published on Dec. 28 in the .

This is very basic research and Chen says it is too early to predict what practical applications this knowledge could produce. “We can only speculate,” he says, because “this is so new that real practical applications haven’t really surfaced.” But he points out that one of the most widely used building materials in the world, concrete, flows as a liquid-like cement paste during construction, and a better ability to understand its process of transition to solid form might be significant for improving its durability or other characteristics.

Controversial finding

The team had previously published their findings about the new transition temperature in water, but the new work extends this to the whole class of liquids. While the findings remain somewhat controversial, Chen says that last month an international symposium devoted to the study of this phenomenon was held in Florence, Italy involving about 50 scientists from various nations.

Benjamin Widom, an emeritus professor of chemistry at Cornell University, says that the researchers’ demonstration of the universality of this crossover phenomenon and the fact that the liquids studied all show roughly the same level of viscosity at their crossover point “is striking,” and adds that “These observations are certain to arouse much interest among those who work in the field, and perhaps even controversy because they contradict long-accepted ideas.”

Liquids become much more viscous as they approach their freezing temperature — that is, they begin to move less like water and more like honey. But the exact progression of this transition is difficult to measure, so the details are still poorly understood. The new research draws on published studies detailing the behavior of 84 different liquids, and the researchers found that a fresh analysis of the data, along with their own experimental work on water, shows a previously unrecognized universal property they all share in terms of how their viscosity and other characteristics change with temperature.

“Measuring viscosity is a very tedious process,” Chen says, and measuring how it changes over tiny increments of temperature is even more difficult. But Chen and his colleagues found that they were able to measure relaxation time of water — which is directly proportional to its viscosity — using a state-of-the-art instrument at the National Institute of Standards and Technology in Washington that shoots neutrons at the material. “We discovered we can measure relaxation time very effectively with this instrument,” Chen said, and they have been carrying out such measurements over the last several years.


This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

Explore further: Scientists capture ultrafast snapshots of light-driven superconductivity

Related Stories

Data Effort Improves Flow Toward 'Greener' Chemistry

Apr 21, 2005

Jeopardy answer: Death Valley and "ionic liquids." Correct question: Where does a little bit of water make a whole lot of difference? Scientists at the National Institute of Standards and Technology (NIST) rep ...

Researchers demystify glasses by studying crystals

Nov 30, 2010

Glass is something we all know about. It's what we sip our drinks from, what we look out of to see what the weather is like before going outside and it is the backbone to our high speed communications infrastructure (optical ...

Ionic Liquid's Makeup Measurably Non-Uniform at the Nanoscale

Nov 10, 2009

(PhysOrg.com) -- Researchers at Texas Tech University, Queen's University in Belfast, Ireland, the University of Rome and the National Research Council in Italy recently made a discovery about the non-uniform chemical compositions ...

Fern's hunger-busting properties supported by research

Nov 15, 2010

Professor Roger Lentle, from the Institute of Food, Nutrition and Human Health at the Massey University, led a team that studied how an extract of the mamaku fern influenced stomach activity. Maori traditionally ...

Bodies for sale

Dec 22, 2010

For some people, intellectual property is about faster computers and better apps. But for Kara Swanson, a new professor at the Northeastern University School of Law, it’s about body products — literally.

Recommended for you

Progress in the fight against quantum dissipation

13 hours ago

(Phys.org) —Scientists at Yale have confirmed a 50-year-old, previously untested theoretical prediction in physics and improved the energy storage time of a quantum switch by several orders of magnitude. ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

gwrede
not rated yet Jan 14, 2011
It would have been polite to mention this temperature for water.
eryksun
5 / 5 (1) Jan 14, 2011
It would have been polite to mention this temperature for water.


Based on the accepted glass transition temperature of water Tg = 136 K, I suppose the dynamic crossover temperature of water is in the range 163-177 K.
Caliban
5 / 5 (3) Jan 14, 2011
The article pointedly ignores providing any description of what characteristics of liquids undergo changes at this newly discovered transition temperature. Does it, for example, represent the temperature of minimum viscosity/maximum miscibility? What about capillary pressure?

A largely useless article, heralding a breakthrough discovery without divulging the least bit in the way of details, with the exception of a general idea of this temperature(at least, from my reading of the article).

More news stories

Progress in the fight against quantum dissipation

(Phys.org) —Scientists at Yale have confirmed a 50-year-old, previously untested theoretical prediction in physics and improved the energy storage time of a quantum switch by several orders of magnitude. ...

New clinical trial launched for advance lung cancer

Cancer Research UK is partnering with pharmaceutical companies AstraZeneca and Pfizer to create a pioneering clinical trial for patients with advanced lung cancer – marking a new era of research into personalised medicines ...

More vets turn to prosthetics to help legless pets

A 9-month-old boxer pup named Duncan barreled down a beach in Oregon, running full tilt on soft sand into YouTube history and showing more than 4 million viewers that he can revel in a good romp despite lacking ...