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The majority of bismuth containing oxides have been taken as important functional materials for applications including photocatalytic water splitting and highly conductive solid electrolytes, which however suffer from property degradation owing to the presence of intermediates. This work initiated a case study on α-Bi2O3nanoparticles with an aim to uncover the origin of property degradation when bismuth oxides that contain traces of secondary phase α-Bi2O3were exposed in either air or aqueous solutions. First, α-Bi2O3nanoparticles with spherical and rod-like morphologies were prepared by developing solution chemistries. It was found that α-Bi2O3transformed partially to Bi2O2CO3when stored in air for 6 months. Such transformation was further accelerated when α-Bi2O3nanoparticles were exposed to water or methylene blue (MB) solution, probably because α-Bi2O3reacts with the species HCO3−as formed by dissolution of CO2from air. Bi2O3surfaces had an unusual tendency to adsorb MB molecules, which in turn prevented the reaction between α-Bi2O3and HCO3−. Consequently, MB solution became clear even without light irradiation. The results reported in this work may help to fully comprehend the property degradation of bismuth containing oxides when used in aqueous solutions. [ABSTRACT FROM AUTHOR]

Rutile TiO2hierarchical microspheres were prepared by a facile solution chemistry method with an aim to achieve nanoscale boundary cavities (NBCs) that can be tailored for optimum giant dielectric performance. The formation of these microspheres proceeded viaa supersaturated spontaneous nucleation and a subsequent radial growth to develop into well-defined 3D hierarchical structures. All microspheres showed a diameter of about 8–10 μm and were constructed by small bundles that consisted of smaller nanowires with a diameter of 8–10 nm. These nanowires are characterized by a preferential growth along the [001] direction which eventually led to the externally exposed (110) planes for hierarchical microspheres. Strikingly, in between these constituent nanowires, there existed plenty of NBCs that created a great number of surface defect dipoles. The NBCs were further tailored by subsequent annealing of the microspheres, as clearly indicated by lattice contraction, linear increase of axis ratio, and red-shift of band-gap energy. As a consequence, rutile TiO2hierarchical microspheres showed an optimum giant permittivity of approximately 104level till 500 Hz at room temperature, compatible to the known giant-dielectric multicomponent materials such as CaCu3Ti4O12. These findings were rationalized in terms of NBCs and the resulting surface defect dipoles. As a reproductive prototype, tailoring of the NBCs in rutile hierarchical microspheres as reported in this work can be applied to a broad class of assembled nanostructures and probably film systems to modulate the dielectric performances for advanced electronic device aspects. [ABSTRACT FROM AUTHOR]

Pure cubic In2O3, orthorhombic InOOH and cubic In(OH)3nanocrystals were separately synthesized viaa one-pot aqueous solvothermal route at low temperature by simply regulating the amount of water in the ternary system H2O–DMF–In(NO3)3·4.5H2O. [ABSTRACT FROM AUTHOR]