Design of transparent thermal insulating thin films of nanoscale-layered oxides

MDR Open Deposited

In industrial application, one of the important features for thermal insulating films in electronic devices is transparency. In order to expand the potential for industrial application, both high transparency and thermal insulating performance must be pursued. For discovery of the material systems which satisfy both properties, the extrapolative search by adaptive learning is applied combining with the previous proposed ITR model. The reduction in thermal conductivity is related to the high density of interfaces which have high ITR rather than to the change of intrinsic thermal conductivity. The consistent thermal conductivity of TiO2 of 1.56 W/mK from 5 nm to 50 nm is observed. The selected material system of SiO2/TiO2, nanoscale-layered thin films synthesized by sputtering, show ultra-low thermal conductivity of 0.23 W/mK and high transparency (>90%, 400-780 nm). The strong substrate dependence is also found that the additional Ti2O3 phase forms as growing on Si substrate and reduces the thermal resistance as relative to the one on quartz substrate. Compared to the current transparent thermal insulating materials, aerogel or polypropylene, the proposed SiO2/TiO2 composites have higher transparency, higher robusticity, good adaptivity to electronics, and lower cost.

Alternative title
  • ナノスケールの層状酸化物を用いた透明断熱薄膜の設計
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