Optical Properties Of ZnS Nanoparticles Research Articles

Effect of cadmium concentration on the structural, morphological, and optical properties of ZnS nanoparticles

The present study is focused on the synthesis and characterization of the Zn1−xCuxS nanoparticles at x = 0, 0.03, 0.05, 0.07 that find application in optoelectronic devices. The synthesized nanoparticles were subjected to various characterizations. From the XRD profile, it was found that Zn1−xCuxS nanoparticles are in a cubic structure. The EDAX spectrum confirms that zinc, sulfur, and cadmium are present in stoichiometric ratios. The FE-SEM and TEM nanographs confirm the formation of spherical-shaped clusters. The crystal structure and texture of the samples were confirmed by SAED patterns. The specific surface area and pore diameter were estimated using a BET surface analyzer. The band gap of the samples was determined using Tauc’s and Cody’s relation, and it decreased as the Cd concentration increased. The Zn1−xCuxS nanoparticles exhibited photoluminescence, and emission peaks were observed in the visible region. The XPS studies confirmed the presence of dopant cadmium in the Cd2+ ions state.

Magnetic, Phonon and Optical Properties of Transition Metal and Rare Earth Ion Doped ZnS Nanoparticles.

The surface, size and ion doping effects on the magnetic, phonon and optical properties of ZnS nanoparticles are studied based on the s-d model including spin-phonon and Coulomb interaction, and using a Green's function theory. The changes of the properties are explained on a microscopic level, due to the different radii between the doping and host ions, which cause different strains-compressive or tensile, and change the exchange interaction constants in our model. The magnetization increases with increasing small transition metal (TM) and rare earth (RE) doping concentration. For larger TM dopants the magnetization decreases. The phonon energies increase with increasing TM, whereas they decrease by RE ions. The phonon damping increases for all doping ions. The changes of the band gap energy with different ion doping concentration is also studied. Band gap changes in doped semiconductors could be due as a result of exchange, s-d, Coulomb and electron-phonon interactions. We have tried to clarify the discrepancies which are reported in the literature in the magnetization and the band gap energy.

Effect of microwave irradiation time on structural and optical properties of ZnS nanoparticles

In this communication, we report the synthesis of ZnS nanoparticles by chemical precipitation of Zn2+ ions with S2- ions in aqueous solution. Freshly formed ZnS nanoparticles (NPs) in colloidal suspension were microwave irradiated for different time intervals in a domestic microwave oven. Effect of microwave irradiation (MWI) time on microstructure, surface morphology and optical properties of NPs are studied using various characterization tools. The structural analysis confirms the influence of MWI time on cubic and crystalline nature of the samples which are in good agreement with selected area electron diffraction (SAED) pattern. The size of the NPs increased with increase in time of MWI. The size increase is consistent with literature reports that microwave irradiation accelerates not only the nucleation but also crystal growth. The band gap of the material tends to decrease as a function of irradiation time. The role of MWI time on surface defect removing process is also explained in detail.

Role of Aluminium Concentration on the Structural, Morphological, and Optical Properties of ZnS Nanoparticles

Role of Aluminium Concentration on the Structural, Morphological, and Optical Properties of ZnS Nanoparticles

Optimization of Synthesis Temperature and Study the Structural and Optical Properties of ZnS Nanoparticles via Simple Chemical Precipitation Method

Optimization of Synthesis Temperature and Study the Structural and Optical Properties of ZnS Nanoparticles via Simple Chemical Precipitation Method

Synthesis and photovoltaic application of ZnS:Cu (3%) nanoparticles

The wet chemical method was used to prepare ZnS:Cu (3%) nanoparticles. The capping agent (mercaptoethanol) was handled during the synthesis process. To investigate the photovoltaic properties of ZnS:Cu (3%) nanoparticles synthesized via the wet chemical method, the incident photon to electron conversion efficiency (IPCE) measurement was performed. The IPCE (%) value at 400 nm was found as 5.12. This result shows that successfully synthesized ZnS:Cu (3%) nanoparticles can be used as promising sensitizers in solar cell technology. The energy band gap value of ZnS:Cu (3%) nanoparticles with cubic structure was determined as approximately 3.92 eV. In this study, it is emphasized that it is possible to develop both photovoltaic properties and optical properties of ZnS nanoparticles by using additive metal.

Effect of Mo and Ti doping concentration on the structural and optical properties of ZnS nanoparticles

In this paper, we report the effect of single phase Mo and Ti doping concentration on the structural and optical properties of the ZnS nanoparticles. The structural and optical properties of the as-synthesized samples have been examined by x-ray diffraction, transmission electron microscopy (TEM), UV–visible near infrared absorption spectroscopy and x-ray photoelectron spectroscopy. TEM characterizations reveal a variation in the doped ZnS nanoparticle size distribution by utilizing different dopants of Mo and Ti. In absorption spectra, a clear red shift of 14 nm is observed with increasing Mo concentration as compared to pure ZnS nanoparticles, while by increasing Ti doping concentration, blue shift of 14 nm is obtained. Moreover, it demonstrates that the value of energy band gap decreases from 4.03 eV to 3.89 eV in case of Mo doping. However, the value of energy band gap have shown a remarkable increase from 4.11 eV to 4.27 eV with increasing Ti doping concentration. Our results provide a new pathway to understand the effect of Mo and Ti doping concentrations on the structural and optical properties of ZnS nanoparticles as it could be the key to tune the properties for future optoelectronic devices.

Synthesis and characterization of ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres

Herein, we synthesized and characterized fluorescent and super paramagnetic ZnS@Fe3O4 nanospheres. First, (3-mercaptopropyl) trimethoxysilane (MPS) capped ZnS quantum dots (QDs) and SiO2 coated Fe3O4 nanoparticles were synthesized separately by using solution growth and co-precipitation techniques. After synthesis and characterization of these two nanoparticles, they were conglutinated together in a nano sized sphere. The QDs were attached to the surface of the Fe3O4 nanoparticles by SiOSi bonds and so SiOSi bonds created a SiO2 network around the nanoparticles during the formation of the ZnS@Fe3O4 nanospheres. The synthesized MPS capped ZnS fluorescent QDs, SiO2 coated magnetite super paramagnetic nanoparticles and ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres were characterized by using UV–Vis Absorption Spectroscopy, Fluorescence Spectroscopy, X-ray analysis, Vibrating Sample Magnetometer analysis, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy. ZnS@Fe3O4 bifunctional nanospheres were shown to retain the magnetic properties of magnetite, while exhibiting the luminescent optical properties of ZnS nanoparticles. The combination of fluorescent and magnetic behaviors of nano composites make them useful for potential applications in the field of bio-medical and environmental.

Preparation and characterization of ZnS nanoparticles prepared by hydrothermal method

ZnS nanoparticles were prepared by hydrothermal method using zinc nitrate [Zn(NO[Formula: see text] ⋅ 6H2O] and thiourea [SC(NH[Formula: see text]] as sources of Zn[Formula: see text] and S[Formula: see text] ions and cetyltrimethyl ammonium bromide [CH3(CH2)[Formula: see text]N[Formula: see text](CH3)3 ⋅ Br[Formula: see text]; CTAB] as a surface active agent. The structural, surface morphology and optical properties of ZnS nanoparticles as a function of growth temperature were investigated. The studies show that ZnS nanoparticles have high transmittance over 70% in the visible light range of 400–800 nm, and it has a strong green emission band at about 520 nm which originates from the recombination of electrons from the energy level of sulfur vacancies with the holes from the energy level of zinc vacancies. With the increase of the growth temperature, the XRD peak intensity and the size of ZnS nanoparticles increase, while the green emission intensity firstly increases and then decreases.

Enhanced dielectric permittivity and photoluminescence in Cr doped ZnS nanoparticles

The effect of Cr doping on dielectric and optical properties of ZnS nanoparticles was systematically investigated at room temperature. Structural analysis confirmed that dopant occupy the regular lattice and interstitial sites in host lattice. Experimental data revealed exceptionally large, low frequency dielectric constant (ϵ′≈106) and enhanced photoluminescence emission in Cr doped ZnS nanoparticles. It is argued that larger value of the dielectric constant in doped nanoparticles originate due to combined effect of Maxwell–Wagner phenomenon and microscopic spontaneous polarization, when larger ionic radius Zn2+ (0.74Å) ions are replaced by smaller ionic radius Cr3+(0.63Å) ions. The huge enhancement in the value of dielectric constant and emission intensity justify the use of doped ZnS nanostructures for various technological applications.

The effect of magnetic metal doping on the structural and the third-order nonlinear optical properties of ZnS nanoparticles

Undoped ZnS nanoparticles and doped with selected magnetic metal ions (Fe2+, Co2+, and Ni2+) have been synthesized by a solvothermal method utilizing low dopant concentrations (1%) and employing poly(vinylpyrrolidone) (PVP) as a capping agent.Cubic structure of undoped and doped ZnS nanoparticles has been observed from X-ray diffraction results. The SEM images show that the particles have smooth surface and the average grain size was found to be in range of 39–60nm for undoped and doped ZnS nanoparticles.The optical direct band gap of undoped and doped ZnS nanoparticles have been studied using UV–vis spectra. The band gap energy value was in the range of 3.49–3.92eV. The result of UV–vis spectroscopy shown that the absorption edge shifted to lower wavelengths with doping. The linear absorption of synthesized nanoparticles have been characterized by optical limiting (OL) method. The third order nonlinear coefficients are investigated with the help of z-scan experimental set-up using Nd: YAG laser. The samples clearly exhibit a two photon absorption effect and self-defocusing process. The results show nonlinear optical properties by doping is reduced.

Effect of Hydrothermal Reaction Temperatures on Structural and Optical Properties of ZnS Nanoparticles

A ZnS nanoparticle was prepared using hydrothermal interaction of zinc acetate with Thiourea in different reaction temperatures (170oC, 180oC, 185oC, 190oC). The structural characterization of synthesized nanoparticle was determined by X-ray diffraction (XRD) which showed a hexagonal structural of ZnS. Scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) analysis were confirmed that the morphology and elemental analysis was formed ZnS nanoparticle. Absorption study has been carried out using UV-VIS spectrophotometer to determine the band gap of ZnS nanoparticle. The optical energy band gap was changed at values equal to (4.16, 4.46, 4.1 and 4.35eV) with different hydrothermal temperatures at (170oC, 180oC, 185oC and 190oC) respectively. However, these values of energy gaps for ZnS nanoparticles are blue shift and larger than that bulk value due to quantum confinement. Fourier Transform Infrared Spectra (FTIR) is recorded in an FTIR spectrometer to verify the presence of ZnS powder. The particle size of ZnS calculated was ranged between 3.5 to 3.9 nm according to Sherrer's equation and the results were compatible when using Effective Mass Approximation (EMA).

Effect of solvent medium on the structural, morphological and optical properties of ZnS nanoparticles synthesized by solvothermal route

Different morphologies of ZnS have been synthesized by a facile solvothermal approach in a mixed solvent made of Ethylenediamine (EN) and distilled water. The effect of solvent medium on the structural, morphological and optical properties of ZnS nanoparticles were investigated. The formation mechanism of different morphologies was proposed based on the experiment results. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), Raman spectroscopy and UV-Vis-IR spectrophotometer. The results show that phase transformation is easily induced and there is a strong correlation between morphology and structure of the ZnS nanocrystals by changing the solvent. The results also show that we have successfully produced hexagonal phase ZnS nanorods with mixed solvent. The grain sizes in the range of 17–22 nm were obtained according to elaboration conditions. Raman spectra show the intense peak at 346 cm−1, which is a typical Raman peak of bulk ZnS crystal, no signature of secondary phases. The band gap of ZnS increased from 3.49 to 3.74 eV with an increase in the EN composition in the solvent, implying that the optical properties of these materials are clearly affected by the synthesis medium.

Starch-assisted synthesis and optical properties of ZnS nanoparticles

ZnS nanoparticles are fabricated via starch-assisted method. The effects of different starch amounts on structure and properties of samples are investigated, and the forming mechanism of ZnS nanoparticles is discussed. By X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis) spectroscopy and fluorescence (FL) spectrometer, their phases, crystalline lattice structure, morphologies, chemical and optical properties are characterized. The results show that ZnS has polycrystalline spherical structure with the mean diameter of 130nm. Sample without starch reveals irregular aggregates with particle size distribution of 0.5–2μm. The band gap value of ZnS is 3.97eV. The chemical interaction exists between starch molecules and ZnS nanoparticles by hydrogen bonds. The stronger FL emission peaks of ZnS synthesized with starch, indicate a larger content of sulfur vacancies or defects than ZnS synthesized without starch.

Effect of nickel doping on structural and optical properties of ZnS nanoparticles

In the present work, solution based simple chemical precipitation method has been used to prepare undoped and Ni-doped ZnS nanoparticles. Zinc acetate, sodium sulfide, and nickel nitrate have been used as precursors for the preparation of Ni-doped ZnS nanoparticles. The X-ray diffraction results revealed that the undoped and Ni-doped ZnS nanoparticles exhibit hexagonal Structure. The average grain size of the prepared nanoparticles was found to lie in the range of 2.6–4.2nm. The SEM images show that the particles have smooth surface and the formation of agglomerated nanoparticles. The compositional analysis results confirm the presence of Ni, Zn and S in the prepared samples. The optical properties of undoped and Ni-doped ZnS quantum dots have been studied using absorption spectra. HRTEM results show that undoped and Ni-doped ZnS nanoparticles exhibit a uniform size distribution with average grain size lying in the range of 2.3–3.6nm. The synthesized nanoparticles exhibited an emission peak centered at around 612nm in the PL spectrum.

Computational study of the optical properties of ZnS nanoparticles

ABSTRACTUsing the density functional theory (DFT) and time dependent DFT, within the generalized gradient approximation (GGA), the electronic and optical properties of stoichiometric (ZnS)n nanoparticles (NP) were calculated. The dependence of the gap on the size (n) of the nanoparticle will be presented. The effect of replacing S atoms with P, Se or Te atoms in the (ZnS)n nanoparticles and its influence in the gap will be also shown.

Tuning optical properties of ZnS nanoparticles in micellar medium at different pH

Synthesis of sodium dodecylsulphate (SDS) capped ZnS nanoparticles with relatively narrow size distribution in acidic and basic medium having average size of 11.3 and 10.7nm respectively have been reported. The nanocrystallites were characterized by using powder X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), selected area electron diffraction (SAED), UV–vis optical absorption and photoluminescence (PL) spectroscopy. The surface charges of the nanoparticles in different mediums were studied in term of zeta potential (ζ). This study correlates the crystallinity with pH of the synthesis medium and optical property of a material. The nanoparticles synthesized in basic medium, possess higher crystallinity while those in acidic medium are microcrystalline in nature. The optical performance of the material in terms of UV absorption and photoluminescence emission at different pH has been compared and correlated with the crystallinity. The optical properties of the as-synthesized ZnS nanoparticles in both the mediums have been explained using vibrational spectroscopy. This study clearly demonstrates how to tune the optical properties of ZnS nanoparticles by changing the reaction medium to find potential applications in the field of electronics. The work reported is a step towards understanding the role of crystallinity to tune the optical properties of a material.

Synthesis and Optical Properties of ZnS Nanoparticles Using Multi-Mercaptan-Terminated Thio Ether as Surface Modifier

ZnS nanoparticles have been prepared by using 2, 3-dimercaptoethylthiopropanethiol (BES) as the coordinating modifier reagent to form Zn-thiol complex at low reaction temperatures. By controlling the experimental conditions, the diameter of the ZnS nanopaticles can be tuned from 43 nm to 115 nm. Systematic experiments were carried out to investigate the factors such as the amounts of the reagents (thiourea and BES) and the temperature, which have great influence on the sizes of the products. And when the content of BES is much higher, ZnS nanopaticles with mercapto surface modification were synthesized. In addition, massive blue shift in UV-vis spectra has been observed and the photoluminescence spectra of the ZnS show a strong emission at approximate 432 nm and 527 nm. Therefore, the preparation and properties studies of different ZnS sizes will offer great opportunities to explore the dependence of a material’s properties and find many interesting applications in the optical devices.

Mechano-chemical synthesis and optical properties of ZnS nanoparticles

In the present work, we report the synthesis and optical properties of ZnS nanoparticles produced by the mechano-chemical route. We used zinc acetate and sodium sulphide as source materials in a high energy planetary ball mill at rotation speed of 300rpm and vial rotation speed of 600rpm with ball to powder (BPR or charge ratio CR) 5:1 for 30 and 90min. The milled powders were washed with methanol to remove impurity and dried at 300°C for 1h. The prepared nanoparticles have been characterized using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), UV–vis–NIR spectrophotometer and Fluorescence spectroscopy. The crystallite size of the synthesized ZnS nanoparticles is found to be in the range 7–8nm which was calculated using Debye–Scherer's formula. The value of optical band gap has been found to be in the range 3.80–4.15eV. Room temperature photoluminescence (PL) spectrum of ZnS samples exhibit a blue emission peaked at 466nm under UV excitation.

Effect of Cr doping on the structural and optical properties of ZnS nanoparticles

AbstractZn1−xCrx S nanoparticles with x = 0.00, 0.005, 0.01, 0.02 and 0.03 were synthesized by chemical co‐precipitation method at room temperature for the first time. Ethylene diamine tetraacetic acid was used as stabilizer. Energy dispersive analysis of X‐rays confirmed the presence of Cr in the samples. The samples were characterized by scanning electron microscopy, X‐ray diffraction (XRD), transmission electron microscopy and optical absorption studies. XRD and selected area electron diffraction results showed that the samples of all compositions crystallized in cubic structure and the lattice parameters decreased linearly with increase in Cr content following Vegard's law indicating that the Cr ions have substituted for Zn in the ZnS lattice. The particle size estimated from XRD was in the range 6–10 nm.The optical absorption studies on the doped samples indicated that the absorption edge blue shifted with respect to those of bulk and nanocrystalline ZnS. The bandgap increased with increasing Cr concentration in a narrow range 3.81–4.03 eV. Photolumonesence studies showed blue emission with appreciable luminescence quenching with increasing Cr concentration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)