Papers by Keyword: ZnS

Abstract: We present the fabrication and optical testing of a fine grating on a ZnS substrate to be used as a wideband infrared spectral disperser and for which the primary application is measurement of the composition of the atmospheres of transiting exoplanets using space-borne infrared astronomical telescopes. A grating with a blaze angle of 2.1 deg. and pitch of 166.667 μm was constructed on a roughly flat 10 mm × 10 mm substrate with a maximum thickness of 1 mm. To obtain high accuracy, the sample was fabricated on a ZnS monocrystal using a high performance processing machine at Canon Inc. The surface roughness measured with a microscope interferometer was 2.6 nm rms. The shape of the fabricated grating edges was examined with a scanning electron microscope. The diffraction efficiency was evaluated by optical experiments at λ = 633 nm, 980 nm, and 1550 nm, and compared with the efficiencies calculated using a Fourier Modal Method. The results showed that the differences between the diffraction efficiencies obtained from experiment and by calculation were between just 0.9 % and 2.4 %. We concluded that the quality of the fabricated ZnS grating was sufficiently high to provide excellent diffraction efficiency for use in the infrared wavelength region. We also present the design of a spectral disperser in CdTe for future more advanced performance.

Abstract: In and Ag co-doped ZnS photocatalysts were successfully prepared by hydrothermal method to extend the light absorption of ZnS to the visible light region. The concentration of In was constant while for Ag was varied to optimize the photocatalytic activity. The In and Ag co-doped ZnS photocatalysts showed smaller band gap energy compared to single doped In (0.1)-ZnS and undoped ZnS. The photocatalytic activity of In and Ag co-doped ZnS photocatalysts was evaluated from the amount of hydrogen produced. The hydrogen evolution rate from aqueous solution containing Na₂SO₃ and Na₂S as sacrificial reagent under visible light irradiation obtained from In and Ag co-doped ZnS is higher compared to the single doped In (0.1)-ZnS when optimum amount of Ag dopant was added. The highest photocatalytic activity is observed for In (0.1),Ag (0.01)-ZnS with hydrogen production rate of 26.82 μmol/h. The higher performance of this photocatalyst is ascribed to the extended visible light absorption, efficient charge separation as well as improved electron transfer associated with synergistic effect of appropriate amount of In and Ag co-doped ZnS.

Abstract: Series samples ZnS and ZnS: Cu²⁺(0.001<x<0.05) have been prepared by a simple and template-free microemulsion improvement method. From the XRD we know that all samples are single phase. The SEM photo shows that the particle sizes are about 20nm~50nm.When the contents of doping Cu²⁺ ions increasing, the particle sizes become larger, which proves that Cu²⁺ ions occupy the position of Zn²⁺ ions. The emission spectrum (ES) indicates that when doping Cu²⁺ ions ,samples show a blue light and the main emission peaks which caused by Cu²⁺ ions t² transition locates at 425nm.

Abstract: A self-assembled film of an amphiphilic perylene tetracarboxylic diimide derivative (N-hexane-N'-(1-phenyl-4-aminoethanol)-1,7-di (4-tert-butylphenoxy) perylene-3,4;9,10-tetracarboxylate diimide, HH-PDI) has been used as the organic template to produce the first example of monodispersed nanoparticles of HH-PDI/ZnS composites. The HH-PDI pure film and HH-PDI/ZnS nanocomposites were characterized by UV-vis absorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and current-voltage (I-V) measurements. Experimental results revealed the film crystallinity and general molecular order for HH-PDI molecules in the nanocomposites are improved effectively in comparison with those in the pure film due to the introduction of ZnS nanocrystals. The electrical conductivity of the HH-PDI/ZnS nanocomposites (6.6×10^-5 S cm^-1) is more than ca. 2 order of magnitude higher than that of (3.6×10^-7 S cm^-1). The present result provides an efficient way to improve the performance of organic semiconductors through introducing inorganic semiconducting nanocrystals.

Abstract: Large quantities of ZnS dentalation nanostructures were synthesized successfully at low temperature using a simple chemical vapor deposition method, and the microstructures and field emission properties of the dentalation structures were investigated. The results indicated that the stem of the dentalation structures is single-crystalline but the surfaces of the teeth are amorphous. The photoluminescence properties show a strong green emission at 520.89 nm due to S vacancy. Investigations on the field emission properties of the ZnS dentalation nanostructures imply that the turn-on field is about 5.56V/μm at an anode-cathode distance of 150μm, which should be attributed to the specific sharp tips and high aspect ratios of the present needle-shaped structure. The field emission behavior of the ZnS obeys Fowler-Nordheim relationship. The results could be valuable for using the ZnS nanostructure as cold-cathode field-emission materials.

Abstract: As the most wide band gap in II-VI compound semiconducting materials, ZnS has many advantages of low-price, innocuity and excellent electro-optical, piezoelectric and pyroelectric properties. ZnS powder with wurtzite structure was synthesized by hydrothermal co-reduction from ZnCl₂ and Sulfur powder. The phase was characterized by X-ray diffraction (XRD), while the size and morphology of the product were characterized by field emission scanning electron microscope (FESEM). The results show that, the powders grow mainly along (0 1 8), (1 1 0), (1 1 24) crystal planes, and the ZnS powders were polygonal nanoflakes with sizes of about 100~300 nm in length or small particles less than 100 nm.

Abstract: ZnS semiconductor nanocrystals (NCs) were prepared by ways from primary materials of ZnCl₂ and Na₂S in water solution. Using the synthesized ZnS NCs, a polyclonal antibody-based ZnS-labelled immunosorbent assay for the determination of estriol (E₃) was developed with atomic absorption spectrophotometry (AAS) as a detector. An immunoaffinity column was applied to testify conjugation between antibody and ZnS NCs. The linear range for determination of estriol is 40.0~600.0 ng.mL^-1, and the limit of detection (LOD) is 10.0 ng.mL^-1. Some serum samples have been analyzed with satisfactory results which are in good agreement with those obtained using ELISA. This work suggests the potential application of NCs as biological probes and AAS as detector in nonisotopic immunoassay.

Abstract: A quantum mechanics study on the electronic properties and copper activation of Fe- and Cd-bearing sphalerite (ZnS) has been done using density-functional theory (DFT). Calculated results indicate that Fe impurity introduces the impurity state near the Fermi level and Fe-S bond shows stronger covalent character. Moreover, Fe impurity could not be replaced by Cu atom due to the more stable electronic structure, which results in the reduced copper adsorption amount. For the Cd-bearing ZnS, the Cd-Zn substitution introduces large lattice distortion and the Cd-S bond shows stronger ionic bonding character than Zn-S bond. For Cd-bearing sphalerite, Cd atom is easily replaced by Cu atom, which could increase the Cu²⁺ adsorption. The experiments of copper adsorption on the synthesized Fe-doped and Cd-doped ZnS samples confirm the simulation prediction.

Abstract: Employing yeast cells as carriers,a novel cell-loaded photocatalyst yeast/ZnS (YC/ZnS) was successfully synthesized. The adsorption performance of methylene blue on the YC/ZnS microspheres was studied. Experimental results showed that the optimized adsorption conditions were 23°C,pH7 and the YC/ZnS dosage 4.5g/L. Under these conditions,the adsorption capacity of YC/ZnS could reach 471.2μg/g. Isotherm modeling revealed that Freundlich equations described well the adsorption of methylene blue onto YC/ZnS.

Abstract: In this work, zinc sulfide (ZnS) thin films were prepared by radio frequency (RF) magnetron sputtering on glass substrates. The effects of sputtering power, working pressure, substrate temperature and annealing treatment on the structural and optical properties of ZnS films were studied using X-ray diffraction and UV-visible spectrometer in detailed.