Framework Flexibility and the Negative Thermal Expansion Mechanism of Copper(I) Oxide, Cu2O

Abstract

The negative thermal expansion (NTE) mechanism in Cu2O has been characterised via mapping of different Cu2O structural flexibility models onto phonons obtained using ab-initio lattice dynamics. Low frequency acoustic modes that are responsible for the NTE in this material correspond to vibrations of rigid O-Cu-O rods. There is also some small contribution from higher frequency optic modes that correspond to rotations of rigid and near-rigid OCu4 tetrahedra as well as of near-rigid O-Cu-O rods. The primary NTE mode also drives a ferroelastic phase transition at high pressure; our calculations predict this to be to an orthorhombic structure with space group Pnnn.

References in corpus (4)

• Simulation study of pressure and temperature dependence of the negative thermal expansion in Zn(CN)${}_2$
• Pressure-induced softening as a common feature of framework structures that have negative thermal expansion
• Common origin of exotic properties in ceramic and hybrid negative thermal expansion materials
• Phonons, Nature of Bonding and Their Relation to Anomalous Thermal Expansion Behavior of M2O (M=Au, Ag, Cu)

Cited by in corpus (4)

• Quantitative understanding of negative thermal expansion in scandium trifluoride from neutron total scattering measurements
• Origins of anisotropic thermal expansion in flexible materials
• Classical model of negative thermal expansion in solids with expanding bonds
• Simulation study of negative thermal expansion in yttrium tungstate Y2W3O12