Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (EITO ≈ 96.7 GPa, EHKUST−1 ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.
Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers
James P. Best, Johann Michler, Jianxi Liu, Zhengbang Wang, Manuel Tsotsalas, Xavier Maeder, Silvana Röse, Vanessa Oberst, Jinxuan Liu, Stefan Walheim, Hartmut Gliemann, Peter G. Weidler, Engelbert Redel, Christof Wöll; Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers. Appl. Phys. Lett. 7 September 2015; 107 (10): 101902. https://doi.org/10.1063/1.4930141
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