6533b85ffe1ef96bd12c1be2
RESEARCH PRODUCT
Reduced thermal conductivity of TiNiSn/HfNiSn superlattices
Emigdio Chávez AngelPeter KratzerTino JaegerUte KolbGerhard JakobGregor FiedlerChristoph EulerPaulina HołujBenjamin BalkeMathis M. Müllersubject
Condensed Matter - Materials ScienceMaterials sciencePhonon scatteringCondensed matter physicsPhononSuperlatticeMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesPhysik (inkl. Astronomie)Condensed Matter PhysicsThermal conductionCondensed Matter::Mesoscopic Systems and Quantum Hall EffectElectronic Optical and Magnetic MaterialsCrystalsymbols.namesakeCondensed Matter::Materials ScienceThermal conductivityThermoelectric effectBoltzmann constantsymbolsdescription
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 $\kappa$ is measured by the 3$\omega$ 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 superlattice periodicity of 3 nm the phonon spectrum mismatch between the superlattice components quantitatively explains the reduction of $\kappa$. For very thin individual layers the interface model breaks down and the artificial crystal shows an enhanced $\kappa$. We also present an enhanced ZT value for all investigated superlattices compared to the single TiNiSn and HfNiSn films.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2015-04-14 |