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ZnO Nanocrystals (zno + nanocrystal)

Distribution by Scientific Domains
Polymers and Materials Science75%

Selected Abstracts

Nanocrystal Shape Control: Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Mater.
Chemical vapor synthesis is a convenient one-step synthesis process for the production of nanocrystalline powders. On page 875, Bacsa et al. report that by controlled variation of experimental parameters, tetrapods (as in image) or spherical ZnO nanocrystals can be selectively obtained directly from Zn metal precursor. Shape control leads to improved optical properties and a better performance when applied as electrodes in dye sensitized solar cells. [source]

Analysis of Raman modes in Mn-doped ZnO nanocrystals

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2009
Shuxia Guo
Abstract Mn-doped ZnO was synthesized using a co-precipitation technique. X-ray diffraction (XRD) measurements and photoluminescence (PL) spectra show that Mn ions are doped into the lattice positions of ZnO. The modes at 202, 330, and 437,cm,1 in the Raman spectrum are assigned as 2E2 (low), E2 (high),E2 (low), and E2 (high) modes of ZnO base, respectively. The mode at 528,cm,1 is ascribed to a local vibrational mode related to Mn. The mode at 580,cm,1 should be an intrinsic mode of ZnO and assigned to E1 longitudinal optical (LO). Its reinforcement should result from a combination of resonance at the excitation wavelength and impurity-induced scattering. [source]

A Novel Approach for Chemical Vapor Synthesis of ZnO Nanocrystals: Optimization of Yield, Crystallinity,

CHEMICAL VAPOR DEPOSITION, Issue 7-9 2009
Moazzam Ali
Abstract The experimental yield of ZnO nanocrystals decreases drastically with increasing reactor temperature in a typical chemical vapor synthesis (CVS) of ZnO nanocrystals from diethylzinc. A novel CVS set-up , a microwave plasma combined with a hot-wall zone , is described to minimize the loss of particles at higher reactor temperatures. The powder samples have been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is observed that the synthesis set-up and reaction temperature have substantial influence not only on yield but also on crystallite size and crystallinity of the pure wurtzite-type ZnO nanocrystals. The lattice constants of ZnO nanocrystals increase with decreasing crystallite size. Defect densities (twin and stacking faults), as well as microstrain, decrease with increasing reactor temperature, whereas crystallinity increases. [source]