Yefeng Yang

Facile synthesis and characterization of ultrathin cerium oxide nanorods

Single-crystalline ultrathin nanorods of CeO2 with uniform diameters of ca. 1.5 nm have been synthesized via an oriented attachment process based on a facile solution-based approach.

Piezoelectric properties of rhombic LiNbO3 nanowires

Rhombic LiNbO3 nanowires along the c-axis were synthesized by using wire-like NH4Nb3O8 as the starting material based on a molten salt reaction with Li2CO3 powders in the KCl melt. Meanwhile, the as-synthesized LiNbO3 nanowires exhibit excellent piezoactivity. An effective piezoelectric coefficient of around 100 pm V−1 could be obtained.

Bandgap engineering and shape control of colloidal CdxZn1−xO nanocrystals

Bandgap engineering and shape control are important and advantageous for potential applications involving colloidal ZnO nanocrystals. Here we demonstrate the syntheses of high quality alloyed Cd(x)Zn(1-x)O nanocrystals with well-defined shapes, from faceted particles to tetrapods and ultrathin nanowires. By comparing the optical bandgaps of the pure ZnO, Cd(x)Zn(1-x)O and Mg(x)Zn(1-x)O nanocrystals with various dimensions, we conclude that bandgap engineering of colloidal ZnO nanocrystals via cadmium alloying effectively narrows the bandgaps. Our study may shed light on the design and syntheses of colloidal alloyed oxide nanocrystals with controlled band structures and shapes.

Highly near-infrared reflecting and transparent conducting ZnO : Ga films: substrate temperature effect

Highly near-infrared (IR) reflecting and transparent conducting Ga-doped ZnO films were deposited on a glass substrate by dc reactive magnetron sputtering. The influence of substrate temperature on the structural, electrical and optical properties of the films was investigated. A lowest resistivity of 3.0 × 10−4 Ω cm was obtained at the substrate temperature of 300 °C. The average transmittance of the films is over 90% in the visible range. The IR transmission cut-off wavelength of the films shifts towards the lower wavelength with increasing electron concentration. All the films have low transmittance and high reflectance in the near-IR region. The IR reflectance of the films shows an increase with increasing electron concentration.

Microstructure and crystal defects in ZnMgO pleated nanosheets

Dislocations in the ZnMgO pleated nanosheets were observed from high-resolution transmission electron microscopy (TEM). The Burgers vector was identified as 1/3⟨112¯3⟩ from the Fourier filtered TEM images. Raman spectra revealed that there were microstructure defects in the ZnMgO nanosheets with the increasing Mg content. The incorporation of the Mg impurities in the ZnMgO nanosheets may promote the congregation of oxygen vacancies and thus facilitate the generation of dislocations. The oxygen deficiency as well as surface dislocations played an important role in determining the optical properties of ZnMgO pleated nanosheets.

Rational synthesis and characterization of heterostructures of ZnO nanocombs with (Zn,Cd)O nanocaps

ZnO/(Zn,Cd)O nanoscale heterostructures were synthesized by a two-stage thermal evaporation method. The heterostructures consisted of ZnO nanocombs and (Zn,Cd)O nanocaps. Two types of nanocaps, wurtzite and cubic (Zn,Cd)O with different Cd contents, could be produced by tuning the growth conditions. The Cd vapour pressure played an important role in determining the morphology, structure and size of the (Zn,Cd)O nanocaps on the branches. Temperature-dependent PL measurements indicated that band-gap engineering of ZnO could be realized in the heterostructures of ZnO nanocombs with cubic (Zn,Cd)O nanocaps. This method can be used to synthesize ZnO nano-heterostructures with other materials.

Synthesis and characterization of ultrathin single-crystalline cerium oxide nanorods

We report a facile solution-based synthetic route to high-quality ultrathin cerium oxide nanorods with diameters of ∼1.3nm. High resolution transmission electron microscopy studies revealed that the nanorods were single-crystalline and grew along the [100] direction. The powder X-ray diffraction pattern of the final products indicated a cubic fluorite structure. The optical properties of the cerium oxide nanorods were explored by UV/Vis absorption and photoluniinescence (PL) measurements at room temperature. The absorption edge of the ultrathin nanorods was obviously blue-shifted with respect to that of the bulk, suggesting the presence of size confinement resulted from the molecular-scale dimension of the nanorods. The current work is of interest for developing UV blocking and shielding materials, and would open up new opportunities for fundamental studies in the field of ultrathin nanorods and nanowires.

Highly near-infrared reflecting and transparent conducting ZnO:Ga

In the inset plot of the previously published figure 8, the horizontal scale in °C was incorrectly numbered from 250 to 450 °C, but should be corrected to range from 200 to 400 °C, as shown below. Figure 8. Spectral dependence of the transmittance of ZnO:Ga films in the wavelength range of 300--450 nm: (a) 200 °C; (b) 250 °C; (c) 300 °C; (d) 350 °C; (e) 400 °C. The inset shows the variation of optical band gap with substrate temperature for ZnO:Ga films.