Negative thermal expansion materials †

Abstract

The vast majority of materials have a positive coefficient of thermal expansion and their volume increases on heating. There has been considerable recent interest in materials which display the unusual property of contracting in volume on heating; i.e. those with a negative coefficient of thermal expansion. This Perspective gives an overview of some of the physical phenomena that can give rise to this unusual effect. Recent insights into negative thermal expansion materials and some of their unusual structural properties are discussed.