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Hydrothermal synthesis and optical properties of hexagonal tungsten oxide nanocrystals assisted by ammonium tartrate
Author(s) -
Pang HuaFeng,
Xiang Xia,
Li ZhiJie,
Fu YongQing,
Zu XiaoTao
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201127456
Subject(s) - materials science , band gap , intercalation (chemistry) , crystallization , inorganic chemistry , photoluminescence , x ray photoelectron spectroscopy , hydrothermal circulation , oxide , nanocrystal , hydrothermal synthesis , ion , nanorod , tungsten , raman spectroscopy , crystallography , chemical engineering , nanotechnology , chemistry , optoelectronics , organic chemistry , engineering , metallurgy , physics , optics
Crystals of hexagonal tungsten oxides (hex‐WO 3 ) have been synthesized using hydrothermal method at 150 °C, assisted by the capping reagent of ammonium tartrate (AT). The XRD and EDX results reveal that the lattice distortion exists in all the samples, possibly due to the defects and the intercalation of the residual sodium ions. Different crystal shapes including plate‐like, urchin‐like, and particle structures were obtained by varying concentration of AT and pH values in the precursor solution. Beside the absorption action of the ${\rm NH}_{4}^{ + } $ and Na + ions, the capping effect can be reinforced by the hydrogen bonding from the tartrate groups in the crystallization process. The bandgap energies were modulated by the size of the nanostructured hex‐WO 3 crystals due to quantum confinement effect, which increases from 2.74 to 3.04 eV. Based on the analysis of the photoluminescence and X‐ray photoelectron spectroscopy, the enhancement of the blue emission of the nanocrystals is assigned as a result of a complex of the local intercalation of the residual sodium ions and the oxygen vacancies or defects.