Structural characterization of (TBA, H)Ca2Nb3O10 nanosheets formed by delamination of a precursor-layered perovskite

(TBA, H)Ca2Nb3O10 nanosheets have been obtained via delamination of a precursor-layered perovskite KCa2Nb3O10. A confined structural characterization was performed using transmission electron microscopy. It has been found that nanosheet fragments with a dimension along the sheet normal consisting of no more than four elementary Ca2Nb3O10 slabs usually curve, showing tubular morphology at the periphery. Then cross-sectional view of the nanosheets is possible, which, along with plane-view observations, reveals that most of the present nanosheets are unilamellar with a thickness of only similar to1.2 nm and high crystallinity is sustained after multiplex synthesis processes including ion exchange, intercalation, and exfoliation. However, chemical analysis indicates partial loss of Ca ions, which appears more severe in thick nanosheet aggregates with more than 4-fold stacking. The soft two-dimensional crystallites contain a considerable density of various defects, e.g., vacancies, antiphase domain boundaries, and local structural collapse. Surface structures have been examined by high-resolution electron microscopy, and atomic reconstruction has been observed. Finally, interfacial structures upon restacking of nanosheets are investigated.