Direct Fabrication of Patterned Functional Ceramic Films by Soft Solution Processing without Post-Firing
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Direct Fabrication of Patterned Functional Ceramic Films by Soft Solution Processing without Post-Firing Masahiro Yoshimura, Tomoaki Watanabe, Takeshi Fujiwara, and Ryo Teranishi Center for Materials Design, Materials and Structures Laboratory Tokyo Institute of Technology 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan ABSTRACT We are proposing an innovative concept and technology, Soft Solution Processing (SSP) for ceramics, which aims to achieve direct fabrication of shaped, sized, located, oriented ceramic materials from solutions without firing and/or sintering. We have successfully fabricated thin and thick films of BaTiO3, SrTiO3, BaWO4, SrMoO4, LiCoO2, and LiNiO2 by SSP in aqueous solutions from room temperature to 200 ºC. In these experiments, interfacial reactions between a solid reactant (substrate) and component(s) in a solution have been designed and realized. By locally activating the reaction and moving the reaction point dynamically in these reactions, we can produce patterned ceramics directly in solution without masking, etching, pattern forming, or any post-heating such as firing or sintering. In this paper we present recent results for patterned ceramic films of PbS, CdS, and LiCoO2. The processes used to produce these films are entirely new, and represent the first examples of successful direct patterning of ceramics from solutions. In previous reports, heating processes have been essential for synthesis and/or sintering of powders and precursors to obtain patterns in ceramic materials. Such processes inevitably cost environmentally and economically. In contrast, our method, where no firing is needed, provides an environmentally and economically less expensive alternative.
INTRODUCTION The present human society is supported by the tremendous consumption of resources, energy and advanced materials. Thin and thick films of functional materials, including ceramics, have traditionally been fabricated by processes requiring huge amounts of energy and resources, some of which are wasted to the environment [1-3]. Such processes have caused the exhaustion of resources and environmental contamination. Recycling of waste materials is possible when we put more energy into the recycling process than into the production/fabrication processes, but this brings about further thermal contamination. In order to address this problem, we must aim to minimize the total energy consumption during the whole life cycle of products, from mining and up-grading of raw materials, through production/fabrication, transportation, usage, and disposal to recycling. Only then will processes become more environmentally friendly [1-3]. In this regard, we are proposing Soft Solution Processing (SSP) for production of advanced materials such as ceramics, semiconductors, composites etc (figure 1) [4]. SSP aims, based upon thermodynamic considerations, to fabricate shaped, sized and controlled advanced materials from aqueous solutions without excess heat and energy consumption and without using expensive equipment and precur
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