While network formation is prevalent in nature, networks are generally not expected in inorganic structures. Exceptions are those cases in which surface states become important, such as nanoparticles. However, even in these cases, the morphology of these networks is difficult to control and they show a large degree of disorder. In this work, we show that highly ordered and interconnected nanoscale networks of functional metal oxides can be fabricated by a combination of polymer imprinting and polymer templating through solution processable methods. We report the fabrication of a number of functional oxide networks (i.e., BiFeO3, SrTiO3, La0.7Ca0.3MnO3, and HfO2) from solution, showing that all the oxide materials tried so far are able to follow the self-assembled network morphology dictated by the polymer structure. These networks were characterized for the overall structure by scanning electron microscopy and atomic force microscopy (AFM). Grazing incidence small angle X-ray scattering showed a good imprint quality on the mm2 scale for the combined networks, which is challenging given that multiple processing steps were involved during the fabrication. The material stoichiometries were investigated by X-ray photoemission spectroscopy and the crystal phases by grazing incidence wide angle X-ray scattering. When electronic functionality is anticipated, the networks behave as expected: conducting AFM on the La0.7Ca0.3MnO3 networks confirmed the conductive character of this composition; and piezoresponse force microscopy of the BiFeO3 network is consistent with the presence of ferroelectric behavior. These nanoscale networks show promise for future applications in adaptable electronics, such as neuromorphic computing or brain-inspired information processing.
Metal oxides are of much interest in a large number of applications, ranging from microelectronics to catalysis, for which reducing the dimensions to the nanoscale is demanded. For many of these applications, the nano-materials need to be arranged in an orderly fashion on a substrate. A typical approach is patterning thin films using lithography, but in the case of functional oxides, this is restricted to sizes down to about 100 nm due to the structural damage caused at the boundaries of the material during processing having a strong impact on the properties. In addition, for applications in which multifunctional or hybrid materials are requested, as in the case of multiferroic composites, standard top-down methods are inadequate. Here, we evaluate different approaches suitable to obtain large areas of ordered nano-sized structures and nanocomposites, with a particular focus on the literature of multiferroic nanocomposites, and we highlight the polymer-templating method as a promising low-cost alternative.
Daniel Mannion opened discussion of the paper by Hyunsang Hwang: This is a question regarding your devices relating to Fig. 21 of your paper (DOI: 10.1039/c8fd00127h). The caption states the potentiation and depression observed in Fig. 21a and 21b respectively are for separate devices with diff
Ella Gale opened discussion of the introductory lecture by Rainer Waser: At the end of your talk you introduced complementary resistance switches, which you used for binary pattern matching. Do you have any insight into how you might use these systems to do computation in the real number space?
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