Dresden 2017 – scientific programme

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DS: Fachverband Dünne Schichten

DS 39: Thin Film Applications

DS 39.8: Talk

Thursday, March 23, 2017, 11:30–11:45, CHE 91

Minimizing thermal conductivity in laser deposited multilayers — •Döring Florian and Krebs Hans-Urlich — Institut für Materialphysik, Universität Göttingen

Minimizing thermal conductivity is essential for modern applications in the field of thermal barrier coatings, thermoelectrics, cryogenics and space-applications. The reduction of thermal conductivity can be achieved by an increase of phonon scattering and phonon localization as well as by a reduction of phonon mean free path and velocity. These effects happen typically in materials with a high amount of interfaces and result in a thermal boundary resistance. Thus, the goals in order to minimize the thermal conductivity are on the one hand to maximize the interface density and on the other hand to maximize the thermal boundary resistance at each interface, which gives a high overall thermal resistance and thereby a low thermal conductivity. Those goals can be achieved by combining materials with a high acoustic mismatch in nanoscale multilayers. A prominent method for this purpose is pulsed laser deposition, which is a very versatile thin film method, allowing combining materials with very different properties such as metals, oxides and polymers and thus fabricating materials with a high density of interfaces between dissimilar materials that show a high thermal resistance. In this contribution, multilayers of W/polycarbonate and W/ZrO2 as well as measurements on their thermal conductivity, showing very low values, are presented. While the first material combination excels by a very high acoustic mismatch, the second material combination is outstanding in terms of thermal stability.