Renaissance of Topotactic Ion-Exchange for Functional Solids with Close Packed Structures |
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Authors: | Eric Gabilondo Shaun O'Donnell Dr Ryan Newell Rachel Broughton Marcelo Mateus Dr Jacob L Jones Dr Paul A Maggard |
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Institution: | 1. Department of Chemistry, North Carolina State University, Raleigh, NC 27695 USA;2. Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 USA |
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Abstract: | Recently, many new, complex, functional oxides have been discovered with the surprising use of topotactic ion-exchange reactions on close-packed structures, such as found for wurtzite, rutile, perovskite, and other structure types. Despite a lack of apparent cation-diffusion pathways in these structure types, synthetic low-temperature transformations are possible with the interdiffusion and exchange of functional cations possessing ns2 stereoactive lone pairs (e. g., Sn(II)) or unpaired ndx electrons (e. g., Co(II)), targeting new and favorable modulations of their electronic, magnetic, or catalytic properties. This enables a synergistic blending of new functionality to an underlying three-dimensional connectivity, i. e., -M−O-M-O-]n, that is maintained during the transformation. In many cases, this tactic represents the only known pathway to prepare thermodynamically unstable solids that otherwise would commonly decompose by phase segregation, such as that recently applied to the discovery of many new small bandgap semiconductors. |
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Keywords: | cation exchange metastability topotactic reaction metal oxides solar energy conversion |
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