Researchers from Iowa State University have developed a method using a series of nanoscale sensors to obtain images and measurements of the stresses and strains of materials subjected to high pressure. The innovation will be instrumental in the development of new materials and phases of matter which will benefit technologies and applications in all fields.
Iowa state’s specialized lab sets the scene for innovation
This week, a team of US scientists published findings from their latest study in the journal Science, which details how they developed new, nanoscale sensor technology to measure the impact of stress on materials at a level of unprecedented detail.
Valery Levitas, professor and mechanical engineer at Iowa State University, has established a lab there that focusses on experimental testing and computational modeling of high-pressure sciences, making it the perfect setting for developing this new technology. Along with his team of highly capable academics, including the paper’s lead author, Norman Yao, an assistant professor of physics at the University of California, and Mehdi Kamrani, a doctoral student in aerospace engineering also at Iowa, Levitas facilitated the development of the innovative new sensors that were described in last week’s publication.
Inserting nanoscale sensors into diamonds
The researchers came up with the idea of inserting a series of nitrogen-vacancy color centers, which are tiny, nanoscale sensors, into diamonds. These characteristically strong diamonds were then used to exert large amounts of pressure on tiny samples of materials. Known as "diamond anvil" experiments, where the material samples are squeezed between two diamonds, the researchers were able to determine the changes in pressure and volume. The scientists used the sensors within the diamonds to relay data about the impact of the pressure on various characteristics of the material.
The system they developed allows images, measurements, and calculations to be made in relation to six different types of materials stress, giving the most comprehensive measure of the impact of pressure on materials to date. Also, the new process gave researchers the capability of measuring the changes in the material’s magnetism caused by changes in pressure.
High-pressure science has long been plagued by the problem of not being able to measure all six key stresses simultaneously because of the issues caused by attempting to measure them all under high pressure. The team at Levitas' lab came up with an ingenious way around this, by twisting the materials after putting them under high pressure, having the impact of immensely reducing phase transformation pressure, and allowing researchers to search for new phases of matter, something that may have applications in numerous fields of technology.
The Iowa lab is also unique in that it is the only one in the world where multi-scale computer modeling for high-pressure diamond anvil experiments is carried out. It was these simulations that allowed the team to reconstruct fields of all six stresses in the entire diamond anvil.
Development will have a significant impact on numerous fields of science
The new sensors created by the team facilitate the investigation of the strength and failure of materials under pressure, as well as enabling the discovery and characterization of exotic phases of matter. The sensors are also able to measure other material properties, such as electric and thermal characteristics.
The establishment of these innovative sensors has opened up new avenues of research, with a large range of experiments now possible due to the ability to quantitatively characterize materials at extreme conditions.
The scientists involved in the project believe that what they have achieved will also have implications in the advancement of high-pressure studies in numerous fields of science, such as chemistry, mechanics, geology, and planetary science.