![]() ![]() The nanosheet exhibited highly efficient photochromic properties, showing reversible color change upon UV irradiation. Cesium tungsten bronze (CsxWO3) is synthesized by solid phase method or liquid phase method with cesium carbonate and sodium tungstate as raw materials. Ca, Na, and Ln on the A -site, with Nb, Ta and Ti on the B -site. Analysis of the absorption profile provided 3.6 eV as indirect band gap energy, which is 0.8 eV larger than that of the bulk layered precursor, probably due to size quantization. Materials with the crystal structure of pyrochlore, general formulation A2B2 O 6Y, have been found to contain a wide variety of metal cations on both the A- and B- sites, e.g. Product Name: Sodium Tungstate Dihydrate Product Number: All applicable American Elements product codes, e.g. The colloidal cesium tungstate nanosheet showed strong absorption of UV light with sharp onset, suggesting a semiconducting nature. In-plane XRD analysis confirmed that the 2D pyrochlore structure was retained. ![]() Microscopic observations by transmission electron microscopy and atomic force microscopy clearly revealed the formation of unilamellar crystallites with a very high 2D anisotropy, a thickness of only approximately 2 nm versus lateral size up to several micrometers. This indicates the total delamination of the layered tungstate into nanosheets of Cs(4)W(11)O(36)(2-). X-ray diffraction (XRD) measurements on gluelike sediment recovered from the colloidal suspension by centrifugation showed a broad pattern of a pronounced wavy profile, which closely matched the square of calculated structure factor for the single host layer. Interlayer Cs ions were replaced with protons by acid exchange, and quaternary ammonium ions were subsequently intercalated under optimized conditions. Layered cesium tungstate, Cs(6+x)W(11)O(36), with two-dimensional (2D) pyrochlore structure was exfoliated into colloidal unilamellar sheets through a soft-chemical process.
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