Flower-shaped Nanostructures Research Articles

Complex nanostructures of ZnO: growth and properties

Variety of complex ZnO nanostructures such as flower-shaped structures, hierarchical and star-shaped nanostructures have been grown by the novel cyclic feeding chemical vapour deposition (CFCVD) process on various substrates at low-temperatures of 475°C to 550°C. Metal organic source, diethyl zinc (DEZn) and oxygen gas was used as source materials for zinc and oxygen, respectively for the growth of ZnO nanostructures synthesised by CFCVD process. The selected area electron diffraction (SAED) pattern of the flower-shaped structures confirmed that the grown products are single-crystalline ZnO. In addition to the ZnO nanostructures grown CFCVD process, comb-like ZnO structures were also synthesised, in a high density, via simple thermal evaporation process by using metallic zinc powder and oxygen as source materials for zinc and oxygen, respectively. The X-ray diffraction pattern of the synthesised comb-like structures exhibited that these structures are possessing single-crystallinity and wurtzite hexagonal phase of ZnO.

Low-Temperature Synthesis of Flower-Shaped CuO Nanostructures by Solution Process: Formation Mechanism and Structural Properties

Flower-shaped CuO nanostructures have been prepared by the simple solution process at 100 °C using copper nitrate, NaOH, and hexamethylenetetramine (HMTA) for 3 h without the use of any complex reagents. The morphological investigations by field emission scanning electron microscope (FESEM) revealed that the flower-shaped nanostructures are monodispersed in large quantity and exhibit the nanocrystalline nature with monoclinic structure. The flower-shaped morphologies are strongly dependent on the concentration of HMTA, presence or absence of NaOH and HMTA, and reaction time. The possible growth mechanism for the formation of flower-shaped CuO products was also discussed in detail.

Low-Temperature Growth of Flower-Shaped UV-Emitting ZnO Nanostructures on Steel Alloy by Thermal Evaporation

Flower-shaped ZnO nanostructures, containing the triangular-shaped petals (sharpened tips and wider bases) have been achieved by simple thermal evaporation of high purity metallic zinc powder in the presence of oxygen at 440 degrees C on steel alloy substrate without the use of metal catalyst or additives. Detailed structural studies confirm that the obtained flower-shaped nanostructures are single crystalline and possesses a wurtzite hexagonal structure, grown along the c-axis in the [0001] direction. Raman and room temperature photoluminescence analysis substantiate a wurtzite hexagonal phase with a good crystal quality and a strong UV emission at 378 nm, respectively, indicating few or no structural defects. Additionally, a detailed possible growth mechanism has also been discussed.

Flower-shaped ZnO nanostructures obtained by cyclic feeding chemical vapour deposition:structural and optical properties

Flower-shaped ZnO nanostructures were grown on Si(100) and Si(111) substrates by cyclicfeeding chemical vapour deposition without the use of a metal catalyst. The structuresobtained on the Si(100) substrate exhibited triangle-shaped leaves with lengths anddiameters in the ranges 300–400 and 90–130 nm, respectively. Uniformly shaped leaves withhexagonal facets originating from one centre were observed on the flower-shapedstructures grown on the Si(111) substrate. Transmission electron microscopy andselected area electron diffraction patterns showed that these structures are highlycrystalline, with the wurtzite hexagonal phase, and preferentially oriented in thec-axis direction. Unlike star-shaped ZnO nanostructures grown on Au-coated siliconsubstrates, the flower-shaped nanostructures showed sharp and strong UV emission at378 nm and broad and weak green emission at 520 nm, indicating a good crystal quality andfew structural defects.