Thermal Conductivity and Disorder in Nonmetallic Materials

Abstract

Experimental results for thermal conductivity λ are presented and discussed for a range of nonmetallic materials. Disorder, involving both static and dynamic aspects, is covered over a range from well-ordered solids to glasses. Amongst intermediately-disordered (ID) solids which are considered the cases of plastic crystal phases, the glassy crystal state, inclusion compounds and chiral substances receive detailed attention. Emphasis is given to relatively-high temperature (T) where results for λ of glasses and ID solids are shown to be similar. It is demonstrated how data for λ(T) which have been measured under isobaric conditions can be transformed to isochoric conditions, and this transformation is shown to be important for purposes of analysis of results. Limitations at high temperature of the phonon picture of heat transport are explored using an empirical approach and an alternative picture involving hopping of localized vibrational excitations is also briefly discussed.

Key Words:

• Thermal conductivity
• disordered materials
• glasses
• high pressure
• phonons