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Abstract: Large-scale SiC–SiO2 core–shell nanowires decorated with carbon nanoparticles have been synthesized on Si substrate using thermal decomposition of ethanol. The amorphous carbon nanoparticles on SiO2 shell are of hemispherical configuration hiving a mean diameter of about 20nm. The average size of carbon nanoparticles estimated from Raman measurement is 23.4nm close to that evaluated from transmission electron microscopic observation. Strong enhancement of blue emission band and appearance of a new yellow emission band were observed in SiC–SiO2 core–shell nanowires decorated with carbon nanoparticles and their origins were discussed. A possible synthesis mechanism of SiC–SiO2 core–shell nanowires decorated with carbon nanoparticles was proposed. [Copyright &y& Elsevier]

Abstract: MoO3 nanoflowers were successfully synthesized on a Si substrate by a facility microwave hydrothermal method. The nanoflowers consisted of tens of nanobelts and the nanobelts were about several micrometers in length, several tens to several hundreds of nanometers in width, and tens of nanometers in thickness. Field-emission measurements showed that the nanoflowers had a relatively low turn-on field of ∼4.3V/μm and their emission was a barrier tunneling quantum-mechanical process. The fluctuations of the emission current were less than 10% over 3h. The low turn-on field and high stability of emission current indicate that the as-grown MoO3 nanobelts exhibit a good field-emission property and have great potential for applications in field-emission devices. [Copyright &y& Elsevier]

Abstract: Cubic and hexagonal NaYF4:Ln3+ (Ln=Eu and Yb/Tm) microcrystals were separately synthesized by an EDTA-assisted solvothermal method. Under 393-nm excitation, the emission spectra of NaYF4:Eu3+ microcrystals show the characteristic Eu3+ emissions. In the excitation spectra of the 610-nm emission, the 7F0 → 5D3 is dominant for the cubic microcrystals, while the 7F0 → 5L6 is dominant for the hexagonal sample. In addition, unusually strong ultraviolet emissions (1I6 → 3H6, 1I6 → 3F4, and 1D2 → 3H6) were observed in the hexagonal NaYF4:Yb3+/Tm3+ microcrystals under 980-nm excitation. In comparison with a cubic sample having the same chemical compositions, the hexagonal microcrystals had a markedly enhanced ability of emitting ultraviolet up-conversion luminescence. [Copyright &y& Elsevier]