The new materials can be designed to contract more or less under heating and so can be matched to cancel the expansion of other materials and to create components that do not change shape when heated.
Dr Arash Mostofi and Dr Nick Bristowe, from Imperial’s Departments of Materials and Physics, noted: “The discovery of how to control thermal expansion in these materials is very exciting. Our understanding of the processes underlying the effect means that we can search for it in related materials in the perovskite family or in other classes of materials with wide applications.”
The contraction, known as negative thermal expansion (NTE), is caused by certain vibrations of atoms within the material, causing them to become closer together on average. The size of the effect depends on the proportions of strontium and calcium in the system. Changing the amount of these two elements allows the amount of NTE to be tuned.
The team, including members from Imperial College London, Oxford University, Diamond Light Source and institutions in Korea and the US, have built the material and demonstrated the effect, measured its crystal structure and simulated it on a computer.
