When materials are structured at the nanoscale, their CTE can change due to several factors:
Surface-to-volume ratio: Nanostructures have a higher surface-to-volume ratio, which can lead to significant surface stress and alter the thermal expansion behavior. Quantum confinement: At the nanoscale, the quantum confinement effects can modify the electronic and phononic states of the material, thereby impacting its CTE. Grain boundaries: Nanomaterials often have numerous grain boundaries that can impede thermal expansion, leading to a different CTE compared to bulk materials.
