Issue 18, 2020, Issue in Progress

Cesium polytungstates with blue-tint-tunable near-infrared absorption


Revisiting Wöhler's method (1824), Cs-doped tungsten bronzes were synthesized by reducing Cs-polytungstate at high temperature, and were pulverized into nanoparticles for determining their optical properties. The high-temperature reduced Cs4W11O35 crystals absorbed strongly in the near-infrared, providing an improved luminous transparency with a less-bluish tint than normal Cs0.32WO3−y synthesized in a reductive atmosphere. The high-temperature reduction caused an orthorhombic-to-hexagonal phase transformation and a nonmetal–metal transition, which was monitored by spectrophotometry, X-ray diffraction, and X-ray photoelectron spectroscopy measurements, assisted by a first-principles analysis using a DFT+U method. The high-temperature reduction of Cs4W11O35 is concluded to decrease the number of W deficiencies and produce oxygen vacancies, releasing both free and trapped electrons into the conduction band and thereby activating the near-infrared absorption. The comparatively narrow bandgap of Cs4W11O35 was identified as the origin of the less-bluish tint of the produced Cs tungsten bronzes.

Graphical abstract: Cesium polytungstates with blue-tint-tunable near-infrared absorption

Article information

Article type
17 Jan 2020
03 Mar 2020
First published
11 Mar 2020
This article is Open Access
Creative Commons BY license

RSC Adv., 2020,10, 10491-10501

Cesium polytungstates with blue-tint-tunable near-infrared absorption

S. Yoshio, M. Wakabayashi and K. Adachi, RSC Adv., 2020, 10, 10491 DOI: 10.1039/D0RA00505C

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