Theories derived by Maltese scientists on how materials and structures “can respond in unexpected ways” have been proven correct by a team of UK researchers.
Prof. Joseph N. Grima, Dr Ruben Gatt, Ms Daphne Attard and co-workers from the Metamaterials Unit within the University’s Faculty of Science will be having their work published in tomorrow’s issue of Science, a world-renowned scientific journal. In their perspective, they show how the theory based on models they derived could be exhibited in real materials.
Tests by UK researchers Fortes, Suard and Knight have been performed on methanol monohydrate and this appeared to behave exactly as predicted by models studied by the Maltese scientists.
With the financial support of the Malta Council for Science and Technology, the team worked on structures and materials which exhibited very unusual properties, including the ability to get fatter rather than thinner when stretched in one direction, shrink when heated, or, expand in at least one direction when compressed on all sides.
Tests have been performed on methanol monohydrate and this appeared to behave exactly as predicted by models studied by the Maltese scientists.
Addressing a news conference this afternoon, Prof. Grima said that materials such as the ones studied by the Maltese scientists could have some very important uses.
“Negative Thermal Expansion (NTE) materials can be used in the manufacture of composite material to tailor their overall thermal expansion coefficient to some particular value.
“Mismatch in the thermal expansion coefficient can have some highly undesirable and possibly costly consequences.
“With the help of NTE inclusions, one may lower the thermal expansion coefficients o composites to some preset value, making it possible to design materials with a tailor-made response to temperature.”
Prof. Grima said that in the electronics industry, NTE materials were used to make substrates and heat sinks that matched the thermal expansion of silicon.
Composites from NTE and conventional materials could be used in telescope and satellite applications to prevent them from changing shape with variations in temperature. NTE materials were also used in laminates to control or eliminate curvatures arising from thermal stresses.
Dr Gatt said that Negative Compressibility (NC) materials could similarly be used in applications requiring extremely sensitive pressure detectors.
“It has also been postulated that NC materials may have a very high refractive index, which would provide substantial advantages in designing optics.”
The Maltese team also works on materials having a negative Poisson’s rate, including the auxetic foams that the university is developing with Methode Electronics (Malta) Ltd.