Fully dense crystalline solids with extremely low lattice thermal conductivity (${\kappa }_L$) are of practical importance for applications including thermoelectric energy conversion and thermal barrier coatings. Here we show that lone-pair electrons can give rise to minimum ${\kappa }_L$ in chalcogenide compounds that contain a nominally trivalent group VA element. Electrostatic repulsion between the lone-pair electrons and neighboring chalcogen ions creates anharmonicity in the lattice, the strength of which is determined by the morphology of the lone-pair orbital and the coordination number of the group VA atom.

• Received 29 August 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.235901