De-icing agent remains stable at more than a million atmospheres of pressure

August 12, 2016

Lawrence Livermore National Laboratory scientists have combined X-ray diffraction and vibrational spectroscopy measurements together with first-principle calculations to examine the high-pressure structural behavior of magnesium chloride.

Magnesium chloride (MgCl2) is well known to be an effective de-icing agent, for example, in the aviation industry. Magnesium compounds, including MgCl2, also could function at extreme conditions as effective biocidal agents and work to neutralize biological weapons. The high pressure properties of these materials are important for understanding and predicting their behavior in complex chemically reactive environments such as detonations that are of interest to the Defense Threat Reduction Agency (DTRA).

The team observed an extensive stability of MgCl2 under pressure that contradicts the well-established structural systematics. The research is published in the Aug. 12 edition of Scientific Reports.

The immediate technical aim of the study was to provide equations of state (EOS) and structural phase diagrams to improve the confidence of semi-empirical thermochemical calculations predicting the products and performance of detonated chemical formulations.

"In order to determine accurate EOS data, we first conducted high-pressure X-ray diffraction measurements up to a nominal detonation pressure of 400,000 times more than our atmospheric pressure," said Joe Zaug an LLNL physical chemist and project leader.

"The EOS data enable the development of thermochemical prediction tools to guide the development of effective formulations to defeat bioagents," said Sorin Bastea, the projects' lead LLNL computational physicist.

"According to previous theoretical studies and the well-established phase diagram of high pressure compounds, MgCl2 should have transformed to a higher coordination number (more dense) and 3D connectivity structure well below 40 GPa through a first order phase transition," said lead author Elissaios (Elis) Stavrou, an LLNL physicist.

In contrast, MgCl2 remained in a low layered structure. Even after crossing past the 1 MBar (1 million atmospheres) pressure limit, no structural phase transition was observed.

The team's experimental results also were confirmed by first principle calculations performed by their collaborator, Assistant Professor Yansun Yao at the University of Saskatchewan. According to Yao, the surprising pressure stability is inherent and not due to a kinetic barrier.

Stavrou explained: "High pressure compounds are archetypal ionic solids and after nearly 50 years of systematic study theorists tend to suggest that these pressure dependent structures and transitions are predictable. Our results highlight the need to re-examine currently established structural systematics and to be prepared for unexpected results."
-end-
This research was funded by the Defense Threat Reduction Agency. Other researchers include Bora Kalkan and Martin Kunz of Lawrence Berkeley National Laboratory.

Founded in 1952, Lawrence Livermore National Laboratory (http://www.llnl.gov) provides solutions to our nation's most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

DOE/Lawrence Livermore National Laboratory

Related Behavior Articles from Brightsurf:

Variety in the migratory behavior of blackcaps
The birds have variable migration strategies.

Fishing for a theory of emergent behavior
Researchers at the University of Tsukuba quantified the collective action of small schools of fish using information theory.

How synaptic changes translate to behavior changes
Learning changes behavior by altering many connections between brain cells in a variety of ways all at the same time, according to a study of sea slugs recently published in JNeurosci.

I won't have what he's having: The brain and socially motivated behavior
Monkeys devalue rewards when they anticipate that another monkey will get them instead.

Unlocking animal behavior through motion
Using physics to study different types of animal motion, such as burrowing worms or flying flocks, can reveal how animals behave in different settings.

AI to help monitor behavior
Algorithms based on artificial intelligence do better at supporting educational and clinical decision-making, according to a new study.

Increasing opportunities for sustainable behavior
To mitigate climate change and safeguard ecosystems, we need to make drastic changes in our consumption and transport behaviors.

Predicting a protein's behavior from its appearance
Researchers at EPFL have developed a new way to predict a protein's interactions with other proteins and biomolecules, and its biochemical activity, merely by observing its surface.

Spirituality affects the behavior of mortgagers
According to Olga Miroshnichenko, a Sc.D in Economics, and a Professor at the Department of Economics and Finance, Tyumen State University, morals affect the thinking of mortgage payers and help them avoid past due payments.

Asking if behavior can be changed on climate crisis
One of the more complex problems facing social psychologists today is whether any intervention can move people to change their behavior about climate change and protecting the environment for the sake of future generations.

Read More: Behavior News and Behavior Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.