Oxygen vacancies and pseudo Jahn‐Teller destabilization in cesium‐doped hexagonal tungsten bronzes

• DOI: 10.1111/jace.16414
• Publication Date: 2019-03-05T06:01:38Z
• Authors: Mika Okada; Katsushi Ono; Satoshi Yoshio; Hideaki Fukuyama; Kenji Adachi
• Keywords: 02 engineering and technology; 0210 nano-technology; 01 natural sciences; 0104 chemical sciences

AbstractStructural and compositional changes of Cs‐doped hexagonal tungsten bronzes (HTB) with respect to variations in oxygen deficiency and alkali content have been investigated in detail through x‐ray diffraction Rietveld analysis, x‐ray photoelectron spectroscopy, and Raman spectroscopy. Cs‐HTB crystallized in a reductive atmosphere is evidenced to generally contain plenty of oxygen defects, and a general formula, CsxWO3−y (0.20 ≤ x ≤ 0.32, 0 < y ≤ 0.46), is proposed. Lattice parameters of Cs‐HTB are observed to vary according to the relation, c (Å) = −3.436a (Å) + 33.062. The coordinated modification of W–O octahedral dimensions suggests the origin of the structural change with increasing x and y to be a destabilization of the pseudo Jahn‐Teller distortion due to donated electrons. The dimensional change of lattice due to electrons emitted from oxygen defects is appraised only 1/18 as that due to electrons from doped alkali ions, suggesting that most electrons from oxygen defects should be localized in Cs‐HTB.