Thermal transport properties of nanoporous zeolite thin films
Hudiono, Yeny C.
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This thesis has addressed several of the fundamental challenges in correlating the structure thermal transport properties of complex nanoporous polycrystalline zeolite materials. Two types of zeolite materials, MFI and LTA, were employed in order to investigate the effects of temperature and both the framework and non-framework cations on the thermal conductivity of zeolite. The thermal conductivity values of both materials were measured using a well intergrown zeolite film 3-omega method. The thermal transport mechanisms in these materials were investigated by separately analyzing the contributions of different phonon scattering processes. This thesis represents our progress towards a robust framework for understanding and predicting thermal transport properties of zeolite materials and complex crystals in general. Furthermore, the important roles of boundary and defect scattering, as illustrated in this thesis, also imply that the thermal conductivity of zeolite materials can be tuned by exploiting not only the composition but also the pore structure. In addition, a non-equilibrium molecular dynamics simulation with external force was developed and employed to predict the thermal conductivity of materials. It has shown that this method can accurately predict the thermal conductivity of simple materials, such as argon and quartz; however, it failed to predict the thermal conductivity of complex materials, such as zeolite. This thesis presents possible factors that can explain the phenomena and future recommendations to elucidate this issue.