Zinc Sulfide

Zinc sulfide [ZnS] thin films were deposited on glass substrates using radio frequency magnetron sputtering. The substrate temperature was varied in the range of 100°C to 400°C. The structural and optical properties of ZnS thin films were characterized with X-ray diffraction [XRD], field emission scanning electron microscopy [FESEM], energy dispersive analysis of X-rays and UV-visible transmission spectra. The XRD analyses indicate that ZnS films have zinc blende structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM data also reveal that the films have nano-size grains with a grain size of approximately 69 nm. The films grown at 350°C exhibit a relatively high transmittance of 80% in the visible region, with an energy band gap of 3.79 eV. These results show that ZnS films are suitable for use as the buffer layer of the Cu(In, Ga)Se2 solar cells.

Optical properties of highly chromium doped (2-4 at.%) zinc sulfide made by pulsed laser deposition have been studied by spectroscopic ellipsometry in the spectral range of 0.73-5.90 eV. The characteristic optical features of the ZnS are a direct bandgap with absorption onset at 3.6 eV, with E 0 , E 1 and E 2 critical points around 3.7, 5.7 and 7 eV. Excitonic effects were observed to be strong in this material -in line with the literature. The sub-bandgap absorption accredited to the chromium doping appears as a broad sub-bandgap feature increasing monotonously with increased doping concentration at a given growth temperature. In this report, we discuss three different approaches to extract and analyze the optical properties in terms of the complex dielectric function.

We present the properties of Cr-doped zinc sulfide (ZnS:Cr) films deposited on Si(100) by pulsed laser deposition (PLD). The films are studied for solar cell application, and to have a high absorption a high Cr content (2.0-5.0 at.%) was intended. It is determined by energy-dispersive X-ray spectroscopy that Cr is relatively uniformely distributed, and Cr increase corresponds to Zn decrease. The results indicate that most Cr atoms substitute Zn sites. Consistently, electron energy loss and X-ray photoelectron spectroscopy (XPS) showed that the films contain mainly Cr 2+ ions. Structural analysis showed that the films are polycrystalline and textured. The films with ∼ 4 % Cr are mainly grown along the hexagonal [001] direction in wurtzite phase. The average lateral grain size decreases with

Single molecular precursors are appropriate starting materials for synthesis of semiconductor nanoparticles (NPs), which allow for the control of atomic ratio, monodispersity, composition and particle size of nanoscaled metallic sulfide nanoparticles. In the present study, we have reported the synthesis of nanostructured chalcogenides pharmacologically active active zinc sulfide nanoparticles (ZnS NPs) using Zn (II) ion inserted thiosemicarbazone ligand as a single molecular precursor .The precursors were thermally pyrolysized using high energy microwave radiations to obtain very fine ZnS nanoparticles. In this synthesis, we use DMSO as a nonpolar solvent for the synthesis of all compounds. The heating of Zinc complex in the non-aqueous environment of DMSO plays a very crucial role in decreasing reaction time, reducing the chances of side reactions and proper conversion of Zn complex into ZnS nanoparticles. In this reaction Zn complex of thiosemicarbazone ligand provides both Zn 2+ and S 2-ions for synthesis of ZnS nanoparticles. The microwave synthesis of ZnS NPs from Zn complex is a very simple, fast, highly effective, efficient and low cost method. All synthesized compounds were characterized by various structural, electronic, vibrational, optical, morphological and pharmacological characterizations. The prepared ZnS NPs were found to crystallize in cubic phase, which generally forms at low temperatures, with the dimensions dependent upon the molar ratio of molecular precursors used. Synthesized ZnS nanomaterials had surface sulfur vacancies that extend their absorption spectra towards the visible region and decreased the bond gap. This allowed ZnS nanoparticles to demonstrate various pharmacological activities like antibacterial, antioxidant and anti-inflammatory activities under normal conditions. Powered X-ray diffraction studies confirms the formation of well -defined equispaced crystalline ZnS NPS. TEM and FE SEM microscopic studies confirmed the elongated tubules structure of ZnS NPs with an average particle size of 60 nm. Sharpe electronic absorption band at 390 nm indicates the synthesis of good quality ZnS NPs. The FT-IR spectral studies confirmed the presence of Zn-S stretching, N-H bending and C=N stretching, vibrations in molecular precursor as Zn(II) complex. The thermal analysis of molecular precursor was performed to investigate the thermal stability of zinc complex. The Zn complex was stable up-to 380 0 c. All synthesized compounds demonstrated excellent pharmacological activities like antibacterial, antioxidant and antiinflammatory activities as compared to standards used in analysis of compounds. The microwave synthesis of ZnS nanoparticles via single molecular precursor in proper stoichiometric ratios is an excellent and an efficient method for synthesizing highly effective bioactive agents which can be considered as good drug candidate for the treatment of various diseases in future.

Gold -cadmium selenide/zinc sulfide (Au -CdSe/ZnS) nanocomposites (NCs) were synthesized and characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, ultraviolet -visible (UV -visible) absorption and photoluminescence (PL) emission spectroscopy. The PL intensity in the Au -CdSe/ZnS NCs system was found to be much greater than that of CdSe/ZnS nanoparticles (NPs) alone, because of the surface-enhanced Raman scattering of Au NPs. Adding Au -CdSe/ZnS NCs to the cyclometalated iridium(III) complex (Ir-complex) greatly enhanced the PL intensity of a triplet emitter. Three double-layered electroluminescence (EL) devices were fabricated where the emitting zone contains the definite mixture of Ir-complex and the NCs [molar concentration of Ir-complex/ NCs = 1:0 (Blank, D-1), 1:1 (D-2) and 1:3 (D-3)] and the device D-2 exhibited optimal EL performances.

This paper reports on the development of a measurement instrument to perform gloss measurements using an image-based detector. The image-based gloss meter was built according to the specifications of the optical layout of a specular gloss meter in a 60°m easurement geometry, as described in ASTM D523-14. The photodiode detector was thereby substituted with a CMOS detector. The optical layout of the system was designed and validated by the use of ray tracing software. A series of 16 matte to high-gloss test samples, with nominal gloss values ranging between 3 and 90 gloss units, was used to compare specular gloss measurements obtained with the developed instrument and a commercial specular gloss meter. An average and maximum deviation of only 1.2 and 2.7 gloss units, respectively, was obtained, confirming the suitability of the system to perform standard specular gloss measurements. The potential benefits of the image-based approach were then studied. By way of example, the optical characterization of orange peel and contrast gloss by the use of the system was discussed, corroborating the fact that the proposed instrument offers important opportunities for a more global characterization of the total gloss impression.

Un doped and doped with Al ZnS thin Films have been fabricated by vacuum evaporation technique under the vacuum of 10-5 Torr on glass substrate at room temperature and with different ratio of Al concentration of thickness (0.8μm). Structure of these films was characterized by X-ray diffraction and Atomic force microscope. The structures of these films grown on glass substrate are in cubic zinc-blende phase and textured along (111) plane. The crystallite size increases from 68.02 to 215.8 nm as the Al concentration increased from pure to 2% Al. The grain size is increase with increasing of Al concentration the surface roughness of the films is decrease with increasing of Al concentration

In this study, we report on a new method for the synthesis of ZnS quantum dots (QDs). The synthesis was carried out at low temperature by a chemical reaction between zinc ions and freshly reduced sulfide ions in ethanol as reaction medium. Zinc chloride and elemental sulfur were used as zinc and sulfur sources, respectively and hydrazine hydrate was used as a strong reducing agent to convert elemental sulfur (S8) into highly reactive sulfide ions (S2−) which react spontaneously with zinc ions. This facile, less toxic, inexpensive route has a high yield for the synthesis of high quality metal sulfide QDs. Transmission electron microscopy (TEM) image analysis and selected area electron diffraction (SAED) reveal that ZnS QDs are less than 3 nm in diameter and are of cubic crystalline phase. The UV-Vis absorption spectrum shows an absorption peak at 253 nm corresponding to a band gap of 4.9 eV, which is high when compared to the bulk value of 3.68 eV revealing strong quantum confinement...

Water contamination with hazardous dyes is a serious environmental issue that concerns humanity. A green technology
to resolve this issue is the use of highly efficient photocatalysts under visible light to degrade these organic molecules.
Adding composite and modifying shape and size on semiconductor materials are attempts to improve the efficacy of these
compositions. The optical, microstructural and photocatalytic features of the compositions were investigated by several
characterization procedures such as XRD, XPS, SEM, and TEM. Here, modifies Scherrer equation, Williamson–Hall (W–H),
and Halder–Wagner method (H–W) have been used to investigate the crystal size and the micro-strain from the XRD peak
broadening analysis. The average crystal size according to Modified Scherrer’s formula was 6.04–10.46 nm for pristine CdS
and CdS/Gd2O3@GO, respectively. While the micro-strain (ɛ) corresponds to 3.88, 4.63, 4.03, and 4.15 for CdS,  Gd2O3,
CdS/Gd2O3, and CdS/Gd2O3@GO. It was also shown that the modest difference in average crystal size acquired by the
Modified Scherrer and Halder–Wagner (HW) forms was related to differences in average particle size classification. As a
result, the Halder–Wagner method was accurate in estimating crystallite size for the compositions. The average roughness
is slightly changed from 4.4 to 4.24 nm for CdS/Gd2O3 and CdS/Gd2O3@GO, respectively. A kinetics investigation further
revealed that the photocatalytic degradation of MB dyes was accompanied by a Langmuir isotherm and a pseudo-second
order reaction rate. The highest adsorption capacity (qe) determined for (type 1) CdS,  Gd2O3, CdS/Gd2O3, and CdS/Gd2O3@
GO adsorption was 5, 0.067, 0.027, and 0.012  mgg−1, respectively. The  R2 values originated from the pseudo-second-order
(type 2) for CdS,  Gd2O3, CdS/Gd2O3, and CdS/  Gd2O3@GO were 0.904, 0,928, 0.825, and 0.977. As a result, the initial
sorption rate (h) is altered between types 1 and 2. In type 2, the pseudo-second-order rate constant (k2) ranges from 0.005
for CdS to 0.011 for CdS/Gd2O3@GO. The Langmuir Hinshelwood and pseudo-second-order kinetic models describe the
photodegradation process. The results demonstrate that the developed compositions can be used as a long-term substance
for dye removal.

P-nitrophenol (PNP) is a toxic organic pollutant and it is difficult to remove from wastewater by means of conventional treatment processes. Therefore, effective and low cost alternative water treatment technologies are required. In the last years there has been a growing interest in advanced oxidation processes involving semiconductor mediated photocatalysis because the process mineralizes many toxic organic pollutants to carbon dioxide and water at ambient temperature under UV light. The aim of this work is to synthetize ZnS photocatalyst starting from formerly ZnO prepared with different precursors such as zinc sulphate and zinc nitrate by means of precipitation method. ZnS was then obtained by sulfuration of ZnO particles. The sulfuration step was carried out at 450°C in presence of N2 gaseous stream containing H2S at 5 vol%. The prepared photocatalysts were characterized from chemical-physical point of view using different techniques (XRD, BET, UV-vis DRS, Raman). The photocatalytic tests were carried out in a recirculating batch cylindrical photoreactor irradiated by a UV-LEDs strip (nominal power of 12W/m and wavelength emission peak at about 365 nm) surrounding the external surface of the reactor. The experimental results evidenced that the optimal sample is ZnS obtained from the sulphuration of ZnO synthetized by zinc sulphate. In particular, this sample was able to achieve about 51% PNP degradation after 240 min of UV light irradiation.

The mist chemical vapor deposition (mist CVD) method, which uses ultrasonically atomized solutions as sources, is an environmental friendly and cost-effective technology for the growth of compound semiconductors. This growth process is realized under atmospheric pressure and allows us to use many kinds of salts, complexes, and compounds with low toxicity for sources. Using the oxidizability of water including the source, most of the previous reports of the mist-CVD method are on oxide materials. In this study, we fabricated zinc sulfide (ZnS) films by mist-CVD method using thiourea-based water solutions as sources. Investigating the growth of ZnS by mist-CVD under various growth conditions and experimental setups, we proposed zinc-chloride complexes are necessary for the growth of ZnS and vaporized mist sources act as precursors.

Gel of tapioca starch (TS) is a suitable matrix for the formation of ZnS, CdS and core-shell ZnS/CdS as well as CdS/ZnS quantum dots (QDs). These QDs reside in the matrix as non-agglomerating 3 -10 nm nanocrystals. It is demonstrated that amylopectin is responsible for the QDs formation rather than amylose. Combination of ZnS with CdS in the core-shell QDs results in the increase in the intensity of emission without any shift of its wavelength.

In this paper an attempt was made to detect Staphylococcal enterotoxin B (SEB) both by electrochemical and fluorescence immunoassay methods using zinc sulphide (ZnS) QDs. Wet-chemical method was adopted for the preparation of fluorescent ZnS QDs (diameter $ 5-10 nm). These QDs were bioconjugated with monoclonal antibodies and then characterized by various method. A detection limit of 0.02 ng mL À1 by fluorescence assay and 1.0 ng mL À1 by electrochemical assay for SEB was achieved. While by sandwich ELISA it is possible to detect 0.24 ng mL À1 only. The sensitivity of all techniques is very good, since the LD 50 of SEB is 20 ng kg À1 . Electrochemical assay is faster, need low-cost instrument, independent to the size of QDs and found to be one of the best alternative methods as compared to the other existing methods studied herein. The presented method could be expanded to the development of electrochemical and fluorescence biosensors for various agents for field and laboratory use.

The present study, for the first time, reports the successful consolidation of chromium doped zinc sulfide (ZnS) polycrystalline infrared (IR) transparent ceramics (maximum transmittance of 67% at 11.6 μm) via hot pressing under vacuum. The phase composition of the as-sintered Cr 2+ :ZnS ceramics was determined to be primarily cubic ZnS sphalerite, with a minor amount of hexagonal ZnS wurtzite. Scanning electron microscopy (SEM) observation of the sintered ceramics showed a highly consolidated microstructure. IR absorption and photoluminescence measurements revealed that the Cr 2+ ions are tetrahedrally coordinated within the ZnS host lattice.

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 (20-30 nm). 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 TiO 2 and SiO 2 submicron particles.

Zinc sulfide (ZnS) and aluminum doped zinc sulfide (ZnS:Al) thin films have been prepared by chemical bath deposition onto glass substrates at 85 °C using non-toxic complexing agents by varying the Al concentration between 0 wt. % and 18 wt. %. The ZnS and ZnS:Al thin films exhibited a hexagonal wurtzite crystal structure and showed (008) preferential orientation. The Field Emission Scanning Electron Microscope (FESEM) images of the film showed that the glass substrate was nicely covered by compact and dense mosaic like nanostructures. The elemental composition of ZnS and ZnS:Al thin films was measured by energy dispersive x-ray spectroscopy. X-ray photoelectron spectroscopy (XPS) demonstrates the doping of Al into ZnS. From the XPS spectra, the binding energy (BE) values were observed to shift toward the lower BE side for increasing aluminum content. Raman spectra were obtained for the undoped and Al doped ZnS films, which exhibit first-order phonon modes at 328.33 cm−1 and 341.66 ...

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In this work, Anti-reflective thin film is made on Germanium (Ge) optical window, which is one of the most used materials in thermal imaging systems. ZnS material was used its optical transmittance between 2-14 m and due to the fact that it has a refractive index proportional to the refractive index of Ge. ZnS thin films have been prepared by Radio Frequency (RF) magnetron sputtering on Germanium (Ge) optical windows for anti-reflection coating (ARC). ZnS films were produced at different thicknesses using RF sputtering system working pressures under 3, 20 and 30 mTorr. The other RF systems parameters such as RF power, deposition temperature were kept constant for all depositions. Crystal structures, optical and surface properties of ZnS thin films were characterized with X-ray diffraction (XRD), Atomic force microscopy (AFM), Fourier transform ınfrared (FTIR) and UV-VIS transmission spectrometer. The characterization results of Ge optical windows coated ZnS thin films grown at 3 mT...

We have measured the effect of pressure on the luminescence and thermoluminescence characteristics of three ZnS phosphors doped with Cu and C1. The total dopant concentration varied in the ratio 1/1.5/2.5, but the CI/Cu ratio was constant at -8/1. The excitation was via the 325-nm (3.82-eV) line of a He-Cd laser. The absorption edge of ZnS is at 3.67 eV at 1 atm and increases by 6.35 meV/kbar, so that at high pressure the excitation is to 'deep levels" provided by the C1. The emission consists of two peaks at 20 000 and 22 000 cm-' assigned to emission from a C1-center to a Zn vacancy and a Cu+ center, respectively. Both emission peaks increased in energy with pressure. The shifts could be explained in terms of the degree of pinning of donor and acceptor levels to the conduction and valence bands. The thermoluminescence data indicated an initial trap depth of 0.3 eV for all three samples. This trap depth increased with pressure at low pressures but leveled at 0.39,0.46, and 0.54 eV for the high-, intermediate-, and low-concentration samples, respectively. The thermoluminescence intensity decreased by 2 orders of magnitude in 40 kbar. The behavior of the thermoluminescence could be explained largely by differences in the nature and behavior of the "deep levels" initially in the conduction band.

This work focuses on the study of zinc sulfide (ZnS) thin films prepared by chemical bath deposition. The effect of the pH ranging from 10.0 to 10.75 on quality of ZnS thin films on SiO 2 substrate is investigated. The effect of pH on the surface showed that the variation of pH has a significant effect on the morphology of the ZnS thin films. The sample with pH value of 10.50 was uniform, free of agglomerates with band gap energy about 3.67 eV. The resistivity of ZnS thin films on SiO 2 substrate with different pH value were about 10 7 Ω cm.

ZnS-PVA nanocomposite thin films are grown by chemical bath deposition (CBD) method by varying the concentration of zinc source. Formation of nanocrystalline hexagonal ZnS is confirmed by X-ray diffraction. Hexagonal form is predominant at some lower concentration. The morphological properties of the films are determined by transmission electron microscope (TEM). The particle size as given by TEM indicates increase in particle size. Bandgap measured from UV-Visible transmission spectra shows a decreasing trend with decrease of Zn source concentration. Photoluminescence (PL) measurement showed blue emission centred at 417 nm and that the intensity decreases with decrease in Zn source concentration.

Zinc sulphide nanoparticles (ZnS NPs) were successfully synthesized by chemical co-precipitation method at 20°C and 40°C using zinc chloride (ZnCl2 ) and sodium sulphide (Na2S) as precursors. Ascorbic acid was used as a capping agent. The synthesized ZnS NPs were characterized by X-ray diffraction (XRD), UV-visible and Fourier transform infrared (FTIR) spectroscopy. UV-visible spectra showed that the bandgap of synthesized NPs was 3.8-3.9 eV at two different temperatures. XRD analysis showed the particles were present in the cubic phase with a zinc blend structure. FTIR spectra were used in the confirmation of the chemical species of the synthesized NPs. The average particle size calculated by using Debye-Scherrer’s equation at 20°C and 40°C was found to be 5.01 and 3.1 nm which indicates that the particle size was temperature-dependent.

The ZnS nanocrystals were prepared in chitosan solution (0.1 wt.%) using a wet ultra-fine milling. The obtained suspension was stable and reached high value of zeta potential (+57 mV). The changes in FTIR spectrum confirmed the successful surface coating of ZnS nanoparticles by chitosan. The prepared ZnS nanocrystals possessed interesting optical properties verified in vitro. Four cancer cells were selected (CaCo-2, HCT116, HeLa, and MCF-7), and after their treatment with the nanosuspension, the distribution of ZnS in the cells was studied using a fluorescence microscope. The particles were clearly seen; they passed through the cell membrane and accumulated in cytosol. The biological activity of the cells was not influenced by nanoparticles, they did not cause cell death, and only the granularity of cells was increased as a consequence of cellular uptake. These results confirm the potential of ZnS nanocrystals using in bio-imaging applications.

Die Konzentrationskette A wird beschrieben und mit ihr der Aktivit ätskoeffizient von ZnS in einer (Zn,Cd)S-Mischphase bei 650 rc C gemessen. F ür den Wechselwirkungsparameter der Mischphase ergibt sich nach der 1. Guggenheimschen N äherung f ür streng regul äre Systeme W = -36,9 kJ/Mol.

CuxS/Zno‐5Cd0‐85 S‐ und CuxS/ CdS‐Heteroübergänge werden unter besonderer Berücksichtigung der Einflüsse der Umgebung (speziell von O, und Wasserdampf) auf die nahe der CuxS‐Ober?äche auftretenden chemischen Spezies oberflächenchemisch charakterisiert.

Cu-Ni co-doped Zn 1-x Al x O (AZO; Al/Zn = 1.5 at.%) films with fixed Ni concentration at 0.5 mol% and different Cu concentrations (0-2.0 % mole ratio) were synthesized on glass substrates using a sol-gel method. The effects of the Cu composition on the structure, electrical and optical properties were examined. X-ray diffraction (XRD) of the Cu-Ni co-doped AZO (CuNi:AZO) films revealed a polycrystalline ZnO phase with a hexagonal wurtzite structure. The stress variation of the CuNi:AZO films were analyzed from the XRD pattern. XPS spectra indicated the existence of two valence states of Cu atoms in Cu ? and Cu 2? states after N 2 /H 2 (95/5) forming gas heat treatment for CuNi:AZO films. Scanning electron microscopy showed that all the films were smooth with a good packing density. The particle size was calculated by both XRD and SEM analysis, and the difference between them has been discussed in detail. Hall measurements indicated that the lowest resistivity of the CuNi:AZO film is approximately 1.16 9 10 -3 X cm at a 1.0 mol% Cu content, which is one order of magnitude lower than that of AZO film (1.01 9 10 -3 X cm) and 43.9 % lower than that of Ni-doped AZO film (2.07 9 10 -3 X cm). All the films exhibited high transmittance in the visible region and showed sharp absorption edges in the UV region. The optical band gap shifted from 3.44 to 3.35 eV with increasing Cu content. This study provides a simple and efficient route for preparing low resistivity and high transparency CuNi:AZO films for optoelectronic applications.

The synthesis of 6-(2,5-dimethoxy-4-(2-aminopropyl)phenyl)hexylthiol, an agonist with a very high affinity for the 5HT 2A serotonin receptor subtype is reported. This agonist was designed to be attached to highly fluorescent cadmium selenide/zinc sulfide core/shells via a thiol at the end of a linker arm. This conjugate has applications in biological assays and biological imaging.

Dissimilatory reduction of sulfate, mediated by various species of sulfate-reducing bacteria (SRB) and a few characterized species of archaea, can be used to remediate acid mine drainage (AMD). Hydrogen sulfide (H 2 S/HS À ) generated by SRB removes toxic metals from AMD as sulfide biominerals. For this, SRB are usually housed in separate reactor vessels to those where metal sulfides are generated; H 2 S is delivered to AMD-containing vessels in solution or as a gas, allowing controlled separation of metal precipitation and facilitating enhanced process control. Industries such as optoelectronics use quantum dots (QDs) in various applications, e.g. as light emitting diodes and in solar photovoltaics. QDs are nanocrystals with semiconductor bands that allow them to absorb light and re-emit it at specific wavelength couples, shifting electrons to a higher energy and then emitting light during the relaxation phase. Traditional QD production is costly and/or complex. We report the use of waste H 2 S gas from an AMD remediation process to synthesize zinc sulfide QDs which are indistinguishable from chemically prepared counterparts with respect to their physical and optical properties, and highlight the potential for a empirical process to convert a gaseous "waste" into a high value product.

Dissimilatory reduction of sulfate, mediated by various species of sulfate-reducing bacteria (SRB) and a few characterized species of archaea, can be used to remediate acid mine drainage (AMD). Hydrogen sulfide (H 2 S/HS À ) generated by SRB removes toxic metals from AMD as sulfide biominerals. For this, SRB are usually housed in separate reactor vessels to those where metal sulfides are generated; H 2 S is delivered to AMD-containing vessels in solution or as a gas, allowing controlled separation of metal precipitation and facilitating enhanced process control. Industries such as optoelectronics use quantum dots (QDs) in various applications, e.g. as light emitting diodes and in solar photovoltaics. QDs are nanocrystals with semiconductor bands that allow them to absorb light and re-emit it at specific wavelength couples, shifting electrons to a higher energy and then emitting light during the relaxation phase. Traditional QD production is costly and/or complex. We report the use of waste H 2 S gas from an AMD remediation process to synthesize zinc sulfide QDs which are indistinguishable from chemically prepared counterparts with respect to their physical and optical properties, and highlight the potential for a empirical process to convert a gaseous "waste" into a high value product.

The macro-structure of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) substrates is characterized by cone-like structures that start growing at the early stages of deposition. As deposition progresses, these cones grow larger and reach centimeter size in height and millimeter size in width. It is challenging to polish out these features from the top layer, particularly for the magnetorheological finishing (MRF) process. A conventional MR fluid tends to leave submillimeter surface artifacts on the finished surface, which is a direct result of the cone-like structure. Here we describe the MRF process of polishing four CVD ZnS substrates, manufactured by four different vendors, with conventional MR fluid at pH 10 and zirconia-coated-CI (carbonyl iron) MR fluids at pH 4, 5, and 6. We report on the surface-texture evolution of the substrates as they were MRF polished with the different fluids. We show that performances of the zirconia-coatedCI MR fluid at pH 4 are significantly higher than that of the same fluid at

Copper doped ZnS nanophosphors with the cubic zinc blende (Sphalerite) structure have been prepared through the wet chemical route in aqueous media. The ZnS:Cu nanoparticles display a widening in the band gap with increase in Cu dopant concentration. The observed green photoluminescence (PL) in ZnS:Cu originates from the transition between the conduction band and the copper acceptor levels. The open aperture Z-scan traces of the ZnS:Cu nanoparticles embedded in PVA matrix, excited at 800 nm using 100 fs laser pulses, show an optical limiting type nonlinearity which is attributed to three photon absorption. An increase in the value of the three photon absorption coefficient is observed with increase in the Cu doping concentration. The increase in the density of intermediate defect levels plays a significant role in the enhancement of three photon absorption in Cu doped ZnS. These studies reveal that Cu doped ZnS nanoparticles in polymer matrices are potential candidates for ultra fast optical limiting applications.

This paper presents results of a contact-angle study performed to revisiting the chemistry and kinetics of sphalerite activation with Cu(II) on the light of the contact angle technique. Sphalerite (ZnS) activation is conducted with the aim of developing a cuprous sulfide layer with chemical affinity toward thiol-type collectors. This is achieved by manipulating the concentration of Cu(II), the conditioning time and the pH of the flotation slurry. The chemistry of the reaction consists of the reduction of Cu(II) to Cu(I) while copper replaces zinc from the external layers of the mineral crystal, to form a cupric sulfide (CuS) which spontaneously transforms to cuprous sulfide (Cu 2 S) and polysulfide (S n 2- ), rendering the activated sphalerite hydrophobic. The activation process follows a second-order kinetics in which the apparent controlling step is the adsorption of Cu(II) on the unreacted mineral surface.

Refinement and thin film synthesis methods were used by members of six different institutions to design antireflection coatings for germanium substrates. The solutions are based on the use of zinc sulfide and germanium layers only. Several systems were found with an average reflectance that is less than 1% in the 7.7 to 12.3 μm spectral region.

In this paper, Ni-doped ZnS (ZnS:Ni 2+ ) nanoparticles (NPs) have been prepared through a chemical method. The average size of the particle is 45 nm. Thin films of the particles have been prepared by using the spin-coating method. The linear and nonlinear optical properties of Ni-doped ZnS thin films and the colloidal solution of them have been studied widely. Using a precise numerical method, the refractive index curve (dispersion curve), absorption coefficient and optical permittivity of Ni-doped ZnS film have been obtained. Using these values, the absorption coefficient of the colloidal solution of Nidoped ZnS particles has been simulated and compared with experimental results. Finally, using the z-scan method at low laser irradiation, the thermooptical effect has been studied and the nonlinear refractive index due to this effect has been reported.

The stoichiometry and rate of the reaction of H2S (0.05-0.80% in N2) with high surface area ZnO have been studied at 273-318 K. Absorption of H2S by ZnO is not accompanied by evolution of the stoichiometric amount of H2O which has a catalytic action via chemisorption as surface hydroxide. Shallow bed reactors have been used to limit the conversion, providing rate data at nearly uniform gas composition. Three reaction regimes have been identified being, in order of decreasing rate, gaseous diffusion-reaction of H2S, formation, desorption, and diffusion of H20, and solid state diffusion. The fast rates appear to depend upon the crystallite size and morphology, as influenced by the thermal and environmental history of the sample and doping of the ZnO by divalent ions or Na+. The rate in the slowest regime is independent of H2S partial pressure and zinc oxide conversion and is promoted by water vapor. The mechanism appears to involve proton transfer from adsorbed H2S to chemisorbed OH.

The stoichiometry and rate of the reaction of H2S (0.05-0.80% in N2) with high surface area ZnO have been studied at 273-318 K. Absorption of H2S by ZnO is not accompanied by evolution of the stoichiometric amount of H2O which has a catalytic action via chemisorption as surface hydroxide. Shallow bed reactors have been used to limit the conversion, providing rate data at nearly uniform gas composition. Three reaction regimes have been identified being, in order of decreasing rate, gaseous diffusion-reaction of H2S, formation, desorption, and diffusion of H20, and solid state diffusion. The fast rates appear to depend upon the crystallite size and morphology, as influenced by the thermal and environmental history of the sample and doping of the ZnO by divalent ions or Na+. The rate in the slowest regime is independent of H2S partial pressure and zinc oxide conversion and is promoted by water vapor. The mechanism appears to involve proton transfer from adsorbed H2S to chemisorbed OH.

The objective of this study is to explore the electrical and optical characterization of zinc selenide (ZnSe) and zinc sulfide (ZnS) semiconductors as cathode materials of an Infrared image converter. The experiments and simulations have been performed for various converter parameters such as pressure, breakdown voltage, interelectrode distance and illumination. The plasma system has been excited by a dc source, and gas discharge phenomena has been determined under a wide atmospheric pressure range, p. The findings show that ZnS and ZnSe have similar electronic behavior in the image converter in general. The measured discharge currents vary for the two cathodes. In the simulations, the electron mobility, thermal velocity, 3D electron density, space and surface charge density, and mean electron energy have been explored in the Ar-filled converter. It has been proven that the two semiconductors exhibit different properties of discharge, in particular, the mobility of electrons, the ionization coefficients, the breakdown voltages U B , thermal velocities of electrons and surface charge densities. According to the experimental and theoretical findings, ZnSe shows better electrical and optical characteristics for the Ar-filled converter.

Hydrogen sulfide (H 2 S) is one of the most toxic and smelly gases emitted from animal production facilities, which also acts as a catalyst poison in many industrial processes. The principal objective of this research was to develop a dry scrubber to adsorb H 2 S gas efficiently from airstreams mimicking air exhausts of animal and poultry barns at the ambient atmospheric condition. Nano zinc oxide (nZnO) coated 3-mm sized glass beads were investigated to adsorb H 2 S gas in a vertical dry scrubber setting. Colloids of nZnO were prepared and thin films of nZnO were grown on the surfaces of commercially available glass beads following a sol-gel method. The sizes of nZnO on glass bead surfaces ranged from nm to µm and found to be clustered due to the repeated coatings on the same surfaces. The energy dispersion spectroscopy (EDS) analysis confirms the presence of sulfur (S) compound that indicated a conversion of H 2 S into zinc sulfide (ZnS) on nZnO coated bead surfaces. The highest H 2 S breakthrough capacity of 2.54 mg H 2 S g-1 sorbent was observed. Heating the beads at 550°C regenerated glass beads effectively but experienced a gradual loss of reactivity as a number of regeneration cycles progressed. This research demonstrated that nZnO supported on glass beads are promising adsorbents for capturing H 2 S gas from airstreams at ambient temperature.

Zinc sulfide (ZnS) thin film was grown by a shallow chemical bath deposition (SCBD) technique. In this technique a highly conducting hot plate was used to heat the substrate, while higher thermal gradient was achieved by a shallow bath of the ZnS solution. Consequently, homogeneous nucleation is reduced and quality of ZnS thin films can be improved by shaking. The main advantage of this technique over a traditional one is that the use of solution can be reduced greatly, which is crucial for cost reduction in practice. The effects of shaking on growth kinetics and film properties were investigated by characterizing the as-grown ZnS thin films by x-ray diffraction, transmittance and scanning electron microscopy (SEM).

The most informative technique for this phase is X-ray diffraction. The lines observed for the 90/10 and neat NaEHOP are listed in Table . A few data were obtained on the 90/10 sample using the high-resolution synchrotron source at Daresbury, UK. These clearly show the double line at ca. 24 A, and a very large spacing of low intensity at ca. 130 A both of which disappear in the La phase but reappear on cooling. As yet we have been unable to index this pattern and plan to make further measurements on the system. In the LI phase the oxypropionate group is fully hydrated. The limited stability of the H! phase and the onset of the La phase at a rather low concentration, so unlike normal soaps, is a simple consequence of an increased alkyl chain volume and can be predicted from the packing constraint model.I4 There is no bicontinuous cubic (V,) phase between HI and La, but a reentrant L1 occurs instead. This has also been observed with short alkyl chain polyoxyethylene surfactants,I5 where it was suggested that the unfavorable entropy change in making one large surfactant aggregate in the VI phase from many tiny ones in L, could be an important factor. A similar phase sequence occurs for shortchain alkylammonium cationic ~urfactants,~~ briefly for some polyhydroxy s u r f a ~t a n t s ~~ and extensively for sodium ricinoleate,26 indicating also that this is a general property of short-chain surfactants. Within the La phase there is lateral swelling on addition of water rather than a linear increase in d,. The concurrent changes in head-group conformation are reflected in the variation of a and the order parameter of bound water. At high surfactant levels there is a competition between the carboxylate and sodium ions for water binding, with the sodium ions being favored at low temperatures, but carboxylatewater binding increases with increasing temperature. The S phase formed at the highest concentrations of NaEHOP is a mesophase. Because it forms at the La boundary where reversed bicontinuous cubic phase (V,) would be expected, it may be classified as an "intermediate" phase having surfactant aggregate curvature between that of La and H2.5v6J7 We have observed similar behavior in other surfactant systems (ref 26 for example), and have so far been equally successful in elucidating their structures. Work on this problem continues.

The photoluminescence (PL) emission from zinc sulfide (ZnS) synthesized by the microwave-assisted solvothermal method in the presence/absence of a capping agent was examined to understand the key role of its PL activity. In addition, we also investigated the electronic structure using a first-principle calculation based on density functional theory (DFT) applied to periodic models at B·LYP level. Two models were selected to simulate the effects of structural deformation on the electronic structure; the ordered o-ZnS model and the disordered d-ZnS model, dislocating the Zn atom, 0.1 Å, in the z-direction. The PLemission in the visible region showed different peak positions and intensities in capped and uncapped ZnS. The PL emission was linked to distinct distortions in lattices and the emission of two colors, green in the capped and blue in the uncapped, was also examined in the light of favorable structural and electronic conditions. The computational simulations indicate that the e...

Highlights ► ► ZnS/G nanocomposites were prepared by a simple solvothermal process. ► ► Electrochemical measurements were carried out in 6M KOH electrolyte. ► ► Cyclic voltammetry showed the excellent capacitive behavior of the composites. ► ► A specific capacitance of 197.1 F/g was observed for ZnS/G-60 nanocomposites.