Year: 2015
Type: article
Abstract: Diminution of the thermal conductivity is a crucial aspect in thermoelectric research. We report a systematic and significant reduction of the cross-plane thermal conductivity in a model system consisting of dc sputtered TiNiSn and HfNiSn half-Heusler superlattices. The reduction of $\ensuremath{\kappa}$ is measured by the $3\ensuremath{\omega}$ method and originates from phonon scattering at the internal interfaces. Heat transport in the superlattices is calculated based on Boltzmann transport theory, including a diffusive mismatch model for the phonons at the internal interfaces. Down to a superlattice periodicity of 3 nm the phonon spectrum mismatch between the superlattice components quantitatively explains the reduction of $\ensuremath{\kappa}$. For very thin individual layers the interface model breaks down and the artificial crystal shows an enhanced $\ensuremath{\kappa}$.
Source: Physical Review B
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,675
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W1769980784