Mn-doped ZnS Nanoparticles Research Articles

CeO2 supported Zn1-xMnxS (x: 0.025, 0.05, 0.075 and 0.10) catalyst for photoremoval of rhodamine B dye

Present work provides a detailed study of enhanced photocatalytic performance of CeO2 coupled Mn-doped ZnS nanoparticles. In a systematic study, undoped and Mn− doped (2.5, 5, 7.5 and 10 mol%) ZnS nanoparticles were synthesized using co-precipitation method. Then, using synthesized samples, heterostructure samples (ZnS/CeO2) were prepared by hydrothermal route. Successful incorporation of Mn ions in ZnS lattice was determined by X-ray diffraction, transmission electron microscopy and Fourier-transform infrared spectroscopy. Optical spectroscopies revealed the associated optical modifications because of Mn-doping and confirmed CeO2 attachment. The specific surface area calculated from N2 sorption isotherms suggested the mesoporous structure of the samples. Rhodamine B (RhB) dye was used to understand the structural modifications of both components for the photocatalytic performance under different radiations. It was observed that hydroxyl radicals (OH∙) were responsible for photo-oxidation of RhB molecule with excellent photostability of synthesized heterostructure sample under UV–visible illumination. To prove photocatalytic activity of catalysts under visible light, additional experiments with the use of vancomycin antibiotic, which do not absorb visible light, were performed. Though Mn doping improves the recombination rate of charge carriers of host ZnS, the attachment of CeO2, not even reduces the optical bandgap (red shift) but contributes to better separation of the photo-excited charge carriers in heterostructure catalysts.

Structural, optical, and magnetic properties of Mn-doped ZnS nanoparticles

Undoped and Mn-doped ZnS nanoparticles were successfully prepared through a coprecipitation method at low-temperature processing. The X-ray diffraction patterns reveal that the undoped and Mn-doped ZnS nanoparticles have polycrystalline nature with cubic ZnS structure. Furthermore, the lattice constant of the ZnS nanoparticles increases with an increase in the Mn doping concentration. Transmission electron microscope images demonstrated the as-synthesized nanoparticles have particle size ranging from 3 to 5 nm with spherical-shaped particles. Optical band gap values were found to increase from 3.32 to 3.50 eV with the increasing Mn doping concentration. The magnetic properties of undoped and Mn-doped ZnS samples were studied using the vibrating sample magnetometer at room temperature. The synthesized undoped ZnS nanoparticles exhibit ferromagnetism, while Mn-doped ZnS nanoparticles showed paramagnetism at room temperature. Moreover, the saturation magnetization of Mn-doped ZnS samples is higher compared to undoped ZnS. The present synthesis technique to produce high-crystalline quality Mn-doped ZnS nanoparticles and prepared nanoparticles has great potential applications in spintronic and optoelectronic devices.

Synthesis of Mn-Doped ZnS Nanoparticles and Its Characterization

ZnS powders doped with manganese (ZnS:Mn) was synthesized by the sol gel method. The structural and optical characteristics are studied using various techniques. Analysis with X-ray diffraction shows that cubic ZnS phase is formed with average crystallite sizes varying between 10 nm and 13 nm. There is no phase transformation due to Mn2+ doping. The formation of ZnS was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. TEM images indicated the spherical shape of the nanoparticles. However, optical study has shown a strong reflectance in the visible range. The band gap (Eg) of ZnS:Mn is varied between 3.51 eV and 3.56 eV. The photoluminescence properties of ZnS:Mn nanopowders were studied.

Structural and Optical Properties of Mn doped ZnS Nanoparticles: Sol-gel and Quantum Chemical Studies

A bstract - In the present work, undoped and Mn-doped ZnS nanoparticles (ZnS:Mn) were growth by the spin coated method at room temperature. The concentration of the Mn ions was changed from 2 to 6%. Different analytical techniques including were used to investigate the influence of Mn concentration on optical properties of produced thin films. In summary, the influence of Mn doping on the optical properties of un-doped ZnS thin films was reported. These results were also compared to the ZnS:Mn thin films produced by different techniques. In UV-Vis. studies, the band gap energy was found to be 3.5–3.8 eV depending on the Mn doping ratio. In addition, undoped and Mn-doped ZnS nanoparticles were theoretically performed as a cluster by semi empirical calculations. In these calculations, the Zn 7 S 7 and Zn 5 Mn 2 S 7 were optimized as a hexagonal wurtzite phase structure by semi-empirical pm6 level. The theoretical band gaps for both molecules were calculated with same method.

Physical and Optical Characterization of Mn-doped ZnS Nanoparticles Prepared via Reverse Micelle Method Assisted by Compressed CO2

This paper presents the study on the Mn-doped ZnS (ZnS:Mn) nanoparticles synthesized using reverse micelle method assisted by compressed CO2 at 60 bar and 40°C. Effects of retention time (30-120 min) on the particle formation were studied. The optical properties, size, morphology, and structure of the resulting particles were investigated. The results showed that ZnS:Mn nanoparticles were successfully formed with particle size ranging from 2 to 3 nm, which showed quantum size effects. The highest photoluminescence (PL) intensity ratio was found at 60 min retention time. The increase in photoluminescence (PL) intensity ratio indicated an increased homogeneity of nanoparticle growth with decreased surface defects.

Effect of the exposure to Mn-doped ZnS nanoparticles on biomarkers in the freshwater western mosquitofish Gambusia affinis

ABSTRACTSynthesized Mn-doped ZnS nanoparticles, with 10% of Mn dopant, were used to investigate their environmental toxicity. Mn-doped ZnS quantum dots (QDs) stabilized by 3-mercaptopropionic acid (MPA) were synthesized in a basic aqueous solution using the nucleation doping. The optical properties and structure of the obtained Mn (10%):ZnS QDs have been characterized by X-ray diffraction, UV–vis, photoluminescence spectroscopies and transmission electron microscopy. The brain, gills and liver stained sections from Gambusia affinis were dissected. Antioxidant enzyme activities (acetylcholinesterase and catalase), as well as malondialdehyde and H2O2 levels, were determined after exposure (94 h) to 14 and 28 mg/L of nanoparticles. The obtained nearly monodisperse Mn(10%):ZnS@MPA QDs have an average diameter of ca. 2.8 nm and a zinc-blende crystal structure. Mn-doped ZnS acts differently on the activities of the biomarkers in a dose-dependent manner. The recorded alterations varied between organs. Such findings provide information on the biological target of nanoparticles and their behaviour within the environment.

Evaluation of cell penetrating peptide coated Mn:ZnS nanoparticles for paclitaxel delivery to cancer cells

This work aimed at formulating paclitaxel (PTX) loaded cell penetrating peptide (CPP) coated Mn doped ZnS nanoparticles (Mn:ZnS NPs) for improved anti-cancer efficacy in vitro and in vivo. The developed PTX loaded Mn:ZnS NPs with different CPPs (PEN, pVEC and R9) showed enhanced anti-cancer effect compared to bare PTX, which has been validated by MTT assay followed by apoptosis assay and DNA fragmentation analysis. The in vivo bio-distribution and anti-cancer efficacy was studied on breast cancer xenograft model showing maximum tumor localization and enhanced therapeutic efficacy with R9 coated Mn:ZnS NPs (R9:Mn:ZnS NPs) and was confirmed by H/E staining. Thus, R9:Mn:ZnS NPs could be an ideal theranostic nano-carrier for PTX with enhanced the rapeutic efficacy toward cancer cells, where penetration and sustainability of therapeutics are essential.

Investigation of Structural and Electrical properties of ZnS and Mn doped ZnS nanoparticle

ZnS and Mn doped ZnS nanoparticles with blende structure have been prepared by hydrothermal synthesis method. Nanoparticles of two samples are very homogeneous with a narrow size distribution of 20-50 nm. The structural and morphological properties of these particles were studied by X-ray diffraction (XRD) and TEM. UV-Visible absorption spectroscopy was used to calculate absorption edges which are found at 306 nm for ZnS and 330 nm for Mn-ZnS nanoparticle.There are strongest photoluminescence peak at 587 nm corresponding to yellow light. That can be used in flat panel display and LED.The temperature variation of resistivity of ZnS and Mn-ZnS pellets are done in the temperature range of 100-300 K, and show semiconducting behavior.

A fluorescent sensor based on one-step fabrication of chitosan/ZnS: Mn2+ composite film for iodine ion detection

Biocompatible chitosan-coated ZnS:Mn2+ composite films were successfully fabricated via a one-step in situ route. The present paper reports the synthesis, characterization and fluorescence studies of Mn doped ZnS nanoparticles films. These are characterized using SEM, DSC, UV–vis Spectroscopy and fluorescence studies. The fluorescence spectra of ZnS:Mn2+ nanoparticles were measured for different concentrations of I− used. The fluorescence emission of the films was sensitive to the presence of I−. The effect of its concentration on the emission of the film decreased significantly with the increasing of I− concentration from 0~3.6 × 10−5 mol/L. The fluorescence dependent on the concentration could be described by correlation equation. The response of the film to the same concentrations of I− was fully reversible. The composite films should potentially be applied to detect I− in biological system and environment.

Ferromagnetic ordering in chemically synthesized ZnS:Mn diluted magnetic semiconductor: A density functional theory explanation

We have carried out DFT calculations to investigate the origin of room temperature ferromagnetism in experimentally obtained Mn doped ZnS magnetic semiconductor. For experimental investigations, the formation of the cubic ZnS structure of ∼4 nm in size is confirmed by XRD and TEM results. Theoretical calculations reveal that Mn doped ZnS system possesses half metallic characteristics in addition to strong p–d hybridization between the d-states of Mn atom and the p-states of surrounding S atoms, which leads to the strong ferromagnetic coupling and is experimentally realized in the M–H curves of Mn doped ZnS nanoparticles. The ferromagnetic coupling between Mn–Mn atoms are studied by using two dopant model, replacing two Zn atoms by two Mn atoms in ZnS supercell, which depicts that ferromagnetic state is always ground state. In calculating formation energies for single and two Mn dopant ZnS systems, negative values of formation energy are obtained indicating of higher stability of the system.

Effect of Mn2+ and Cu2+ co-doping on structural and luminescent properties of ZnS nanoparticles

Undoped and transition metal (Cu, Mn, Cu:Mn) doped ZnS nanoparticles are synthesized by chemical co-precipitation method via an aqueous synthesis route. Synthesized samples are characterized by various techniques for their structural and optical properties. Crystallite size obtained from X-Ray Diffraction (XRD) is 1.68, 1.87, 1.50, 1.42nm for undoped, Cu, Mn, Cu:Mn doped ZnS nanoparticles. The XRD, High Resolution Transmission Electron Microscopy, and Selected Area Electron Diffraction confirm the evolution of stable hexagonal phase of ZnS nanoparticles at low temperature. Energy Dispersive Spectroscopy confirms the doping of nanoparticles. Blue shift in UV absorbance shows the increase in optical bandgap with decrease in particle size. The Photoluminescence studies exhibit blue, yellow and red emission in visible region. Surface functionalization of nanoparticles is confirmed from Fourier Transform Infra Red spectroscopy. The present samples are tunable in wider range of emission and are prospective candidates for biological labels due to their fluorescent properties.

Optical properties and toxicity of undoped and Mn-doped ZnS semiconductor nanoparticles synthesized through the aqueous route

Undoped and Mn-doped ZnS nanoparticles were synthesized at 95 °C in basic aqueous solution using the nucleation-doping strategy. Various samples of the Mn:ZnS NPs with 5, 10 and 20% of Mn dopant have been prepared and characterized using X-ray diffraction, energy-dispersive X-ray analysis, high resolution electron microscopy and photoluminescence (PL) measurements. When increasing the concentration of manganese Mn, the photoluminescence intensity gradually decreases. The PL spectra of the Mn-doped ZnS nanoparticles at room temperature exhibit both, the 450 nm blue defect-related emission and the 592 nm orange Mn2+ emission. It is vital to obtain NPs that meet the application requirements, however their environmental toxicity needs to be investigated. In this study, the induction of oxidative stress within the digestive gland of the Ruditapes decussatus organism (clam) is described. Antioxidant enzyme activities (superoxide dismutase (SOD) and catalase (CAT)) as well as malondialdehyde (MDA) levels have been determined in the digestive gland after exposure to 100 μg/L of ZnS, ZnS:Mn (5%), ZnS:Mn (10%) and ZnS:Mn (20%).The nanomaterials studied exhibit different responses in the digestive gland. Undoped Mn-ZnS has no effect on the markers considered, showing the limited interaction between this nanoparticle and the cells of the test organisms. In contrast, Mn-doped ZnS increases the activities of SOD and CAT and the level of MDA species, although this toxicity is highly dependent on the chemical properties of the material.These findings provide ideas for future considerations of ZnS nanoparticles, as well as information on the interaction between these materials and an aquatic environment.These data are the first evidence available of the formation of ZnS NPs using aqueous method and are an indication of the importance of knowing the biological target of the NPs when testing their potential impact on environmental model organisms.

Paramagnetic nature of Mn doped ZnS nano particles in opto electronic device application

Manganese (Mn2+) doped ZnS nano sized powder was prepared by co precipitation method with different concentration from 1 to 5 %. The X-ray diffraction pattern indicates that the prepared powders are in cubic structure with the crystallite sizes lie in the range of 10–12 nm. Diffuse reflectance studies enlightens that an increment in the band gap (3.38–3.55 eV) with increasing dopant. The morphology and size of the sample could be intuitively determined by field emission scanning electron microscope and it shows that ZnS and Mn doped ZnS nanoparticles are appeared as spherical shape. The replacement of Zn by Mn is confirmed by energy dispersive analysis. TEM images confirm the spherical shape of the nanoparticles and SAED images exhibit the crystalline nature and confirm the cubic nature of the synthesized samples. The prepared luminescent nanoparticles of Mn doped ZnS have emission peak at around 617 nm. The symmetry and electronic structure of the Mn doped samples are studied with electron paramagnetic resonance.The paramagnetic nature of Mn doped ZnS nano particles are validated by using vibrating sample magnetometer spectra at room temperature. Thermal analysis measurement of the samples shows that the thermal stability of Mn doped ZnS is higher than the undoped ZnS. This corroborates that ZnS:Mn doping is attributed to the removal of water and it enhanced the crystallinity.

Optimization of ultrasound-assisted dispersive solid-phase microextraction based on nanoparticles followed by spectrophotometry for the simultaneous determination of dyes using experimental design

A simple, low cost and ultrasensitive method for the simultaneous preconcentration and determination of trace amount of auramine-O and malachite green in aqueous media following accumulation on novel and lower toxicity nanomaterials by ultrasound-assisted dispersive solid phase micro-extraction (UA-DSPME) procedure combined with spectrophotometric has been described. The Mn doped ZnS nanoparticles loaded on activated carbon were characterized by Field emission scanning electron microscopy (FE-SEM), particle size distribution, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) analyses and subsequently were used as green and efficient material for dyes accumulation. Contribution of experimental variables such as ultrasonic time, ultrasonic temperature, adsorbent mass, vortex time, ionic strength, pH and elution volume were optimized through experimental design, and while the preconcentrated analytes were efficiently eluted by acetone. Preliminary Plackett–Burman design was applied for selection of most significant factors and giving useful information about their main and interaction part of significant variables like ultrasonic time, adsorbent mass, elution volume and pH were obtained by central composite design combined with response surface analysis and optimum experimental conditions was set at pH of 8.0, 1.2mg of adsorbent, 150μL eluent and 3.7min sonication. Under optimized conditions, the average recoveries (five replicates) for two dyes (spiked at 500.0ngmL−1) changes in the range of 92.80–97.70% with acceptable RSD% less than 4.0% over a linear range of 3.0–5000.0ngmL−1 for the AO and MG in water samples with regression coefficients (R2) of 0.9975 and 0.9977, respectively. Acceptable limits of detection of 0.91 and 0.61ngmL−1 for AO and MG, respectively and high accuracy and repeatability are unique advantages of present method to improve the figures of merit for their accurate determination at trace level in complicated materials.

Studies on photo- and thermal stability of PVA-encapsulated Mn-doped ZnS nanoparticles

In this study, an aqueous-based synthesis route has been developed to prepare highly luminescent polyvinyl alcohol (PVA)-capped manganese-doped ZnS quantum dots (QDs). The QDs showed markedly blue shift in their optical absorbance, indicating strong quantum size effect and the average diameter of the QDs calculated ~3 nm. The QDs showed high-intensity Mn2+-related orange luminescence at 585 nm with a very low-intensity peak at 430 nm for the surface defect states. X-ray powder diffraction, transmission electron microscopy, UV–visible spectroscopy and spectrofluorometry have been used to characterize the doped QDs. Studies on the thermal and photochemical stability of the photoluminescence properties are carried out, which showed that after 5 h of photoexcitation and 30 min of 70 °C treatments, the nanoparticles retain almost 40 % of their initial quantum yield. Our systematic investigation shows that these PVA-capped Mn:ZnS QDs may be used as fluorescent labels in biological applications.

Synthesis, characterization and photoluminescence studies of Mn doped ZnS nanoparticles

The present paper reports the synthesis, characterization and photoluminescence (PL) studies of Mn doped ZnS nanoparticles prepared by chemical precipitation method using mercaptoethanol as a capping agent. The nanoparticles were characterized by X-ray diffraction (XRD), field emission gun scanning electron microscope (FEGSEM), and high resolution transmission electron microscope (HRTEM). When the concentrations of capping agent (merceptoethanol) used are 0M, 0.01M, 0.025M, 0.040M, and 0.060M, the sizes of the nanoparticles are 2.98nm, 2.80nm, 2.61nm, 2.20nm and 2.10nm, respectively. Two peaks are obtained in the PL spectra of ZnS:Mn nanoparticles for the excitation wavelength of 220nm, in which the first peak shifts from 400nm to 388nm with decreasing size of nanocrystals, and the second peak lies at 583nm and it does not shift with reducing size of nanocrystals. The PL spectra of ZnS:Mn nanoparticles were measured for different concentrations of merceptoethanol used. The concentration of Mn was kept 1.2%, in which two peaks were found for each sample of ZnS:Mn nanocrystals. The intensities of both the PL peaks increase with reducing size of the nanoparticles. The PL emission centered at 583nm is the characteristics emission of Mn-ion which can be attributed to a 4T1→6A1 transition. However, the blue emission around 400nm is very broad and originates from the radiative recombination involving defect states in the ZnS nanocrystals. Expressions derived for the dependence of PL intensities of peak-I and peak-II on the size of nanoparticles are in good agreement with experimental results.

Structural and Optical Properties of White Light Emitting ZnS:Mn(2+) Nanoparticles at Different Synthesis Temperatures.

We report of the synthesis and characterisation of white emitting ZnS:Mn(2+) nanoparticles. The spectroscopic properties and the crystal structure of Mn doped ZnS nanoparticles are studied here to provide a better understanding on how the luminescence emission and the crystalline composition are influenced by the synthesis temperature. The synthesis of the samples were carried out by the simple wet chemical precipitation method. The influence of synthesis temperature on structure and optical properties were studied at constant Mn concentration. The nanoparticles were structurally characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD studies show the phase singularity of Mn doped ZnS particles having zinc-blende (cubic) structure at all temperatures. The band gap of the doped samples are red shifted with temperature. Electron Paramagnetic Resonance (EPR) spectra exhibited resonance signals, characteristic of Mn(2+). Incorporation of Mn in the ZnS nanoparticles was confirmed by Inductively Coupled Plasma- Atomic Emission Spectroscopic studies (ICP-AES). The samples show an efficient emission of yellow-orange light centred at 590nm which is characteristic of Mn(2+) along with a blue emission at 435nm due to sulfur vacancy. The overall emission is white at all temperatures with CIE co-ordinates in close agreement with achromatic white.

High potential of Mn-doped ZnS nanoparticles with different dopant concentrations as novel MRI contrast agents: synthesis and in vitro relaxivity studies

Over several decades, metal-doped quantum dots (QDs) with core–shell structure have been studied as dual probes: fluorescence and magnetic resonance imaging (MRI) probes (Dixit et al., Mater Lett 63(30):2669–2671, 2009). However, metal-doped nanoparticles, in which the majority of metal ions are close to the surface, can affect their efficacy as MRI contrast agents (CAs). In this context, herein the high potential of synthesized Mn-doped ZnS QDs via polyol method as imaging probe is demonstrated. The mean diameters of QDs were measured via transmission electron microscopy (TEM) and X-ray diffraction (XRD). Optical and magnetic properties of MnZnS nanoparticles were characterized using fluorescence spectroscopy and super quanducting interference devices magnetometer and electron paramagnetic resonance system, respectively. T1- and T2-weighted images of nanoparticles in aqueous solution were acquired from spin–echo sequences at 3 T. From TEM images and XRD spectra of the prepared nanoparticles, it is observed that the average diameter of particles does not significantly change with Mn dopant content (~1.6–1.9 nm). All three samples exhibit broad blue emission under UV light excitation. According to the MRI studies, MnZnS nanoparticles generate strong T1 contrast enhancement (bright T1-weighted images) at the low concentration (<0.1 mM). The MnZnS nanoparticles exhibit the high longitudinal (r 1) relaxivity that increases from 20.34 to 75.5 mM−1 s−1 with the Mn dopant contents varying between 10 and 30 %. Strong signal intensity on T1-weighted images and high r 1 with $$\frac{{r_{2} }}{{r_{1} }} \approx 1$$ can demonstrate the high potential of the synthesized Mn:ZnS nanoparticles, which can serve as an effective T1 CA.

Synthesis and Characterization of Pure and Mn Doped Zinc Sulphide Nanoparticles and Nanofluids

In this work, pure ZnS and Mn doped ZnS nanoparticles are synthesized by simple chemical precipitation method. The structure of pure zinc sulphide and Mn doped zinc sulphide sample are analyzed by X-ray diffraction technique. The morphological structure of zinc sulphide and Mn2+doped zinc sulphide nanoparticles are studied using scanning electron microscope (SEM). The average particle sizes of pure ZnS nanoparticles are determined to be from 29 nm to 44 nm and Mn doped ZnS nanoparticles are determined to be from 99 nm to 135 nm. The optical properties of pure and Mn doped ZnS nanoparticles have been investigated by photoluminescence (PL) spectroscopy. The emission spectrum of Mn2+doped with ZnS particles of the present study shows blue shift of the yellow-orange emission peak at 590 nm. Nanofluids are prepared for six different concentrations by dispersing pure and Mn2+doped ZnS nanoparticles in de-ionized water. Thermal conductivity studies are carried out for both nanofluid systems and the results are discussed.

Preparation and characterization of Mn-doped ZnS nanoparticles

Mn-doped ZnS nanoparticles are synthesized by simple and cost effective chemical precipitation method. This diluted magnetic semiconductor is characterized by various techniques such as energy dispersive X-ray analysis, scanning electron microscopy, X-ray diffraction, photoluminescence and UV–Vis spectroscopy. High purity of the sample is confirmed by energy dispersive X-ray analysis. Sub-micrometer nanocrystals are observed using scanning electron microscope. Hexagonal phase of the material is confirmed by X-ray diffraction studies, and the micro-structural properties such as grain size, strain, dislocation density and texture coefficient are examined. High value of texture coefficient indicates the well-crystalline nature of the material. The band gap, Urbach energy and steepness parameter are calculated from the absorption spectrum. The band gap is also calculated from photoluminescence. The Stokes’s shift, Urbach energy and steepness parameter are reported in the case of Mn-doped ZnS for the first time.