We derive within the dielectric-continuum model an integral equation that defines interface and confined polar optical-phonon modes in nanocrystals with a wurtzite crystal structure. It is demonstrated theoretically that, while the frequency of confined polar optical phonons in zinc-blende nanocrystals is equal to that of the bulk crystal phonons, the confined polar optical phonons in wurtzite ...

Precursor-reduction method is employed to synthesize nanostructures of ZnTe. The shape of zinc blende ZnTe nanocrystals could be influenced by reaction temperature, concentration of the precursors as well as the use of stabilizing agent. By controlling the synthetic conditions, three types of nanoscaled ZnTe, quasi-spherical ZnTe nanocrystals, ZnTe nanobelts and ZnTe nanorods have been observed...

We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sul...

Here we report a low-cost and "green" phosphine-free route for the size- and shape-controlled synthesis of high-quality zinc blende (cubic) ZnSe nanocrystals. To avoid the use of expensive and toxic solvents such as trioctylphosphine (TOP) or tributylphosphine (TBP), SeO(2) was dispersed in 1-octadecene (ODE) as a chalcogen precursor. It has been found that the temperature and the surface ligan...

background: galvanization is the process of coating steel or cast iron pieces with a thin layer of zinc allowing protection against corrosion. one of the important hazards in this industry is exposure to zinc compounds specially zinc oxide fumes and dusts. in this study we evaluated chronic effects of zinc oxide on the respiratory tract of galvanizers. method : 188 workers were selected from a ...

optical modeling was applied for obtaining absorbance spectra and band gap values for different morphology of zno semiconductor. in optical modeling, the relative permittivity scalars of zinc oxide coral like nanorods were calculated using the bruggeman homogenization formalism. zno nano rods (zonrs) as a nucleus layer were fabricated on the indium tin oxide (ito) by chronoamperometry (ca) in a...

background : incidence of  white  spots due  to  demineralization of  enamel  and  gingival problems  is  an  unacceptable  result  of  orthodontic  treatment.  plaque  accumulation  and bacterial biofilm growth are responsible for these phenomena. the resin-based dental composites used as bonding agents in orthodontics play a major role in mentioned problems. as recent researches assert the an...

Metal–oxide–semiconductor capacitor structure with metal nanocrystals embedded in the gate oxide for the application of nonvolatile memory (NVM) is fabricated. Optimal process parameters are investigated and Au nanocrystals are adopted in this paper. High-frequency capacitance versus voltage (C–V ) and conductance versus voltage (G–V ) measurements demonstrate the memory effect of the structure...