ZnS Powders Research Articles

Complex hierarchical arrangements of stacked nanoplates in Al‐doped ZnO

AbstractAl‐doped micro‐ and nanostructures have been grown by an evaporation–deposition method with a mixture of ZnS and Al2O3 powders as precursor. It has been found that the presence of Al is the cause of the growth of complex morphologies, as rods formed by stacks of nanoplates and other complex hierarchical structures. The role of Al in the growth process has been investigated by electron microscopy techniques. Al‐rich particles in specific sites of a central rod lead to hierachical growth. Transmission electron microscopy shows that in some cases the Al‐rich zones are clusters of spinel ZnAl2O4 nanoparticles adhered to ZnO nanorods. Al incorporation into the structures and the dopant effect on the luminescence behavior of the ZnO structures were investigated by energy dispersive spectroscopy and by cathodoluminescence.

Phase Evolution of Cubic ZnS Annealed in Mild Oxidizing Atmosphere

ZnS thin films are prepared by thermal evaporation of high-purity ZnS powder on quartz glass substrates. The samples were annealed in floating argon at temperatures from 300°C to 900°C. The effects of annealing temperature on the structural and optical properties were investigated by x-ray diffraction (XRD), scanning electron microscope (SEM) and optical absorption. The results show that annealing below 500°C is beneficial to improve the quality of ZnS films. When the annealing temperature exceeds 500°C, ZnS is gradually oxidized into ZnSO4, which has evident influences on the structural and optical properties of ZnS films.

Synthesis of nanocrystalline ZnS using biologically generated sulfide

This work describes the synthesis of ZnS powders in high yield and via a straightforward process, under ambient conditions (temperature and pressure), by adding to aqueous zinc (II) a nutrient solution containing biologically generated sulfide from sulfate-reducing bacteria (SRB). The powders obtained as above were composed mainly of ZnS (sphalerite) nanoparticles (NP's) exhibiting a spheroidal morphology (20–30nm). The NP's morphological properties and crystalline phase were not markedly altered by the SRB growth media composition neither by the presence of bacterial cells. The relevance of this method to obtain ZnS supported solid substrates has been demonstrated by performing the synthesis in the presence of TiO2 and SiO2 submicron particles.

대기 분위기에서 ZnS의 산화에 의해 생성된 야구 배트 형상의 ZnO 결정과 음극선형광 특성

ZnO crystals with a baseball bat shape were synthesized without any catalysts through a simple thermal oxidation of ZnS powder in alumina crucible under air atmosphere. SEM images demonstrated that the bat structure was composed of two pieces of ZnO crystals, i.e hexagonal-shaped rod and inverted cone-shaped rod. X-ray diffraction (XRD) pattern revealed that the ZnO crystals had wurtzite hexagonal structure. Energy dispersive X-ray (EDX) spectrum showed that the ZnO was of high purity. A strong green emission peak at 510 nm was observed in cathodoluminescece spectrum.

Facile Synthesis of Hierarchical ZnS Microspheres and their Photocatalytic Properties

Hexagonal ZnS nanostructured spheres self-assembled from ZnS nanocrystals were successfully synthesized through a facile hydrothermal method using 1-butyl-3-methlyimidazole thiocyanate ([BMIM][SCN]) as both sulfur source and capping ligand. By combining the results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), ultraviolet–visible (UV–vis) absorption spectra, a structural and morphological characterization of the products was performed. The photocatalytic activity of ZnS microspheres had been tested by degradation of Rhodamine B (RB) under UV light compared to commercial ZnS powders, which indicated that the as-syntherized ZnS spheres exhibited enhanced photocatalytic activity for degradation of RB.

Synthesis of pencil-shaped ZnO nanowires using sunlight

ZnO nanowires with pencil shape were synthesized in several seconds through a simple thermal evaporation of ZnS powder using sunlight under air atmosphere. ZnS powder was used as a source material. Light from the sun was used to heat and evaporate the ZnS powder. The sunlight was converged on the ZnS powder by a fresnel lens, and then the ZnS powder was evaporated and oxidized in air. ZnO nanowires with a diameter of about 100nm and lengths up to several micrometers were fabricated. Any catalysts were not used in the synthesis of ZnO nanowires, from which it is suggested that the ZnO nanowires were grown by a simple evaporation–condensation mechanism. This synthetic method using sunlight must be a green technique with low energy consumption and without any environmental pollution.

The Growth of Porous ZnO Nanowires by Thermal Oxidation of ZnS Nanowires

The growth of porous ZnO nanowires (NWs) via phase transformation of ZnS NWs at 500-850 degrees C in air was studied. The ZnS NWs were first synthesized by thermal evaporation of ZnS powder at 1100 degrees C in Ar. On subsequent annealing at 500 degrees C in air, discrete ZnO epilayers formed on the surface of ZnS NWs. At 600 degrees C, polycrystalline ZnO and the crack along the (0001) interface between the ZnO epilayer and ZnS NW were observed. At 700-750 degrees C ZnS NWs transformed to ZnO NWs, meanwhile nanopores and interfacial cracks were observed in the ZnO NWs. Two factors, the evaporation of SO2 and SO3 and the stress induced by the incompatible structure at the interface of ZnO epilayer and ZnS NW, can be responsible for the formation of porous ZnO NWs from ZnS NW templates on annealing at 700-750 degrees C in air. Rapid growth of ZnO at 850 degrees C could heal the pores and cracks and thus resulted in the well-crystallized ZnO NWs.

공기 중 대기압 분위기에서 ZnS의 산화에 의해 생성된 벨트형상과 빗 형상의 ZnO 결정

ZnO crystals with belt and comb shapes were synthesized without any catalysts through a simple thermal oxidation of ZnS powder in alumina crucible under air atmosphere. X-ray diffraction (XRD) pattern revealed that the ZnO crystals had wurtzite structure of hexagonal phase. Energy dispersive x-ray (EDX) spectra showed that the ZnO was of high purity. In the cathodoluminescece spectra obtained for the ZnO crystals with belt and comb shapes, a strong ultraviolet emission centered at 380nm was observed, which indicates the ZnO crystal has high crystalline quality.

Microstructures, Growth Mechanism of ZnS Nanomatrials Farbicated by Physical Vapor Deposition

In this paper, one-dimensional ZnS nanostructures were fabricated in a conventional tube furnace by physical vapor deposition method using commercial ZnS powder as the starting materials. The morphologies, microstructures of the products were characterized. The results revealed that the products showed different morphology in different deposition temperature area. The growth mechanisms of the products were also discussed. The nanowires and triangular nanosheets formed via a vapor-liquid-solid process, while the nanobelts formed via a vapor-solid process. The key factors which influenced the morphologies of the products were discussed.

Enhanced violet emission from ZnS nanowires annealed in an oxygen atmosphere

The influence of thermal annealing in an oxygen atmosphere on the photoluminescence properties of ZnS nanowires has been investigated. ZnS nanowires with the diameters of a few tens of nanometers and the lengths of a few hundreds of micrometers were synthesized by thermal evaporation of ZnS powders on Au-coated Si substrates. The ZnS nanowires had an emission band centered at approximately 430 nm in the violet region. The intensity of the violet emission was enhanced significantly by annealing the ZnS nanowires at 500 °C in an oxygen atmosphere for 45 min. The possible sources for the violet emission enhancement by annealing in an O 2 atmosphere are as follows: (1) the Zn 2+ vacancies formed in the nanowires. (2) the oxygen impurity atoms, which have diffused from the O 2 annealing atmosphere into the nanowires.

Synthesis, structure, and photoluminescence properties of ZnSSe alloy nanorods

ZnSSe alloy nanorods were prepared on gold (Au)-coated Si (100) substrates by the thermal evaporation of a mixture of ZnSe and ZnS powders. The nanorods were straight, 70–150 nm in width, and up to a few tens of micrometers in length. Transmission electron microscopy and X-ray diffraction indicated that the nanorods were ZnSSe single crystals with a wurtzite-type hexagonal close-packed structure. The photoluminescence measurements showed that the ZnSe nanorods had a strong emission band centered at approximately 500 nm in the blue-green region. The blue-green emission band corresponding to the deep-level emission of the ZnSSe nanorods showed no shift. On the other hand, a shoulder of the band in the blue region corresponding to the near-band edge (NBE) emission band shifted continuously from 466 nm to a lower wavelength region with increasing composition x in ZnSe 1− x S x from 0 to 0.41. The blue-green emission intensity of the ZnSSe nanrods also increased with increasing composition x. The enhancement of blue-green emission might be due to the increase in structural defects, such as dislocations and stacking faults in the nanorods.

Research on Photoluminescence Characteristics of the Active Cl-Doped ZnS

A active Cl-doping for photoluminescent ZnS powder has been carried out by thermal decomposed AlCl3·6H2O in a quartz tube. Room temperature photoluminescence of the Cl-doped ZnS powder has been investigated using a photoluminescence spectrometer with 365 nm excitation wave length. A strong blue photoluminescence with maximum peak about 450 nm and green photoluminescence with maximum peak about 500 nm can be observed if the doping temperature in range of 800 ~ 900 °C and 1100 ~1200 °C, respectively. The structural characterizations of the Cl-doped ZnS powders were performed with X-ray diffraction (XRD) and the mechanism of photoluminescence was preliminarily discussed.

Fe solubility, growth mechanism, and luminescence of Fe doped ZnO nanowires and nanorods grown by evaporation-deposition

Fe doped ZnO nanowires, nanorods, and urchin-like nanostructures have been grown using an evaporation-deposition method with compacted mixtures of ZnS and Fe2O3 powders, with different Fe contents as precursors. Treatments at 950 °C under argon flow lead to the growth of iron doped nanowires, nanorods, and other nanostructures on the surface of the compacted sample. The incorporation of iron into the nanostructures has been investigated via energy dispersive spectroscopy as well as by cathodoluminescence in a scanning electron microscope and photoluminescence in an optical microscope. The iron content in the structures is limited to the range of 0.5–0.7 at.% and does not depend on the content in the precursor. Bright and dark field imaging and twist contour analysis via transmission electron microscopy support the possibility of a dislocation driven growth of the nanowires.

Synthesis Aligned ZnS Nanocone and its Photoluminescence

We report the synthesis and characterization of ZnS nanostructures, which were grown by thermal evaporation of the ZnS powder at high temperature using iron network as the collection substrate. Scanning electron microscopy investigations show that the products present taper-like morphologies. Transmission electron microscopy studies indicate ZnS nanostructures are well crystallized. The formation mechanism of the novel nanostructure is discussed on the basis of the experimental results; The nanostructure is formed due to a fast growth of ZnS nanowire along [0001] and the subsequent “epitaxial” radial growth of the ZnS nanocone along the six (01-10) surfaces around the nanowire. A strong room-temperature photoluminescence in ZnS nanostructures has been demonstrated.

Self-assembled three-dimensional Al-doped ZnO nanorod networks

Al-doped ZnO nanorod networks and other microstructures have been grown by a thermal evaporation–deposition method with a mixture of ZnS and Al2O3 powders as precursor. Some of the grown structures consist of star-like arrays of nanorods arranged around a central axis with nearly four-fold symmetry. Scanning electron microscopy (SEM) observations indicate that these arrays are the origin of large well-ordered three-dimensional networks of nanorods resulting from the perpendicular growth of lateral branches in every nanorod. CL in SEM has been used to study the influence of Al doping on the emission. Regions with high Al content, about 1 at%, show a luminescence band at about 1.98 eV.

Synthesis and optical properties of wurtzite ZnS nanorings

ZnS nanorings have been synthesized via thermal evaporation of ZnS powders at 1050 °C for the first time. The ZnS nanorings grew along the [ 10 1 ¯ 0 ] direction with a high density of stacking faults along the [0001] direction. The ZnS nanorings were believed to be formed by strain induced bending. This mechanism of ZnS nanoring formation is totally different from those proposed for the formation of ZnO, ZnSe, AlN and GaN nanorings via coiling of their polar surface and long-rang electrostatic interaction. This synthesis method of ZnS nanoring suggests that similar ring-like structures of other II–VI semiconducting nanomaterials may be synthesized.

Crystalline Cr^2+:ZnSe/chalcogenide glass composites as active mid-IR materials

We propose new transition metal (TM)-doped ZnSe/As₂S₃:As₂Se₃ composite materials for mid-IR fiber lasers. The composites are the suspension of crystalline micro- and nanosized TM²⁺:ZnSe or TM²⁺:ZnS powders in chalcogenide glasses with the refraction index matching. Mid-IR room-temperature lasing of Cr²⁺:ZnSe/As₂S₃:As₂Se₃ microcomposite material is demonstrated at the 2.4 μm wavelength.

Preparation of W–Ta thin-film thermocouple on diamond anvil cell for in-situ temperature measurement under high pressure

In this paper, a W-Ta thin-film thermocouple has been integrated on a diamond anvil cell by thin-film deposition and photolithography methods. The thermocouple was calibrated and its thermal electromotive force was studied under high pressure. The results indicate that the thermal electromotive force of the thermocouple exhibits a linear relationship with temperature and is not associated with pressure. The resistivity measurement of ZnS powders under high pressure at different temperatures shows that the phase transition pressure decreases as the temperature increases.

Fabrication and luminescence properties of In 2O 3-capped ZnS nanowires

ZnS-core/In 2O 3-shell nanowires have been prepared by using a two-step process: thermal evaporation of ZnS powders on Si(1 0 0) substrates coated with Au thin films and sputter-deposition of In 2O 3. The ZnS nanowires were a few tens of nanometers in diameter and a few hundreds of micrometers in length. ZnS nanowires have an emission band centered at approximately 570 nm in the yellow region. The yellow emission has been enhanced in intensity by capping the ZnS nanowires with In 2O 3 presumably due to the increase in the concentrations of indium and oxygen interstitials in the very surface region of the ZnS cores and further enhanced by annealing in a reduction atmosphere maybe because of the increase in the concentration of Au Zn − in the ZnS cores. In contrast, the yellow emission intensity has been decreased by annealing in an oxidation atmosphere due to the conversion of ZnS into ZnO as a result of the reaction of ZnS in the cores with oxygen.

ZnO and ZnS composited tri-crystal nanoribbons

ZnO and ZnS composited tri-crystal nanoribbons were fabricated by one-step thermal evaporation of ZnS and CuO powders. The tri-crystal nanoribbons have typical length of about 10 μm and width of 100–300 nm. The tri-crystal nanoribbon was composed of three intersected nanoribbons by 120°, which had a thickness of 50 nm with a growth direction along [10–10]. The rough nanoribbon contained several grains and the averaged elemental enrichment of Zn:O:S was 1:0.72:0.28. The tri-crystal nanoribbons exhibited three emission peaks at room temperature, which are associated to band gap and defect emissions of ZnO and ZnS. This 3D composited nanocrystal has potential applications in optoelectronics and energy-harvesting devices.