Investigation of structural,optical and morphological properties of copper doped zinc sulphide nanoparticles

Semiconductor nanoparticles doped with transition metal ions can influence the transition probabilities and electronic structure. The undoped and copper doped zinc sulphide nanoparticles with various concentrations are synthesized by wet chemical co-precipitation method. These nanoparticles are characterized by using X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), UV–visible (UV–vis) absorption spectroscopy, Fourier Transform Infrared (FT-IR) Spectroscopy, conductivity measurement and time-resolved photoluminescence studies. X-ray powder diffraction analysis reveals that the synthesized samples have cubic zinc blende structure. The Scanning Electron Microscope shows the synthesized nanoparticles are agglomerated. The UV–visible spectra reveal the absorption edge is red shifted. The FT-IR spectra show vibrational peaks around 617 cm⁻¹ which indicate the presence of Cu–S stretching modes. The AC conductivity measurement confirms the semiconducting nature and shows a marked increase in conductivity as the doping concentration of copper increases. The photoluminescence shows that the emission at 426 nm may be due to transition from the conduction band to the zinc vacancies. These transition metal ions doped semiconductor nanoparticles have important applications in solid state lighting, imaging, and other photonic devices.     

Biologically synthesized copper sulfide nanoparticles: Production and characterization

In the present research, copper sulfide nanoparticles were synthesized through a low-cost and environmentally friendly method using the fungus Fusarium oxysporum for the first time. The extracellularly generated nanoparticles were characterized by UV–vis, Florescence Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and Transmission Electron Microscopy (TEM). According to the UV–vis, Florescence and FTIR analysis, it was confirmed that the biosynthesized nanoparticles were created of copper sulfide composition. Moreover, from the morphological point of view, TEM images demonstrated that spherical particles having the size of 2–5 nm were entangled in spherical peptide shells which were about 20 nm in diameter.     

The role of oxidizing agents in the structural and morphological properties of CeO2 nanoparticles

Cerium oxide (CeO₂) nanoparticles with good crystallinity and smooth surface are prepared by chemical precipitation method with different bases (NH₃, NaOH and KOH) using cerium nitrate as a source material. The effect of precipitating agents on the growth of cerium oxide nanoparticles are investigated by Photoluminescence (PL), X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FTIR), thermo gravimetric–differential thermal analysis (TG-DTA), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and X-ray Photoelectron Spectroscopy (XPS). Cubic fluorite crystallites are detected by XRD pattern with preferred orientation along (1 1 1) direction. PL spectra revealed the presence of a strong and broad emission band at425 nm due to the blue shift in the visible region. The broad band below 700 cm⁻¹ is due to the envelope of the phonon band of metal oxide (Ce–O) network as revealed by the IR spectra. The TG-DTA curves revealed that the total weight loss of the samples is 19.67% when the samples are heated upto 800 °C. SEM images exhibits weakly agglomerated spheroid crystallites are obtained with the typical size in the range 10–50 nm. TEM images display that the particles are nearly spherical and square in shape with diameter 8–12 nm. XPS spectrum confirms the existence of Ce⁴⁺ oxidation states in CeO₂samples.     

Microwave combustion synthesis of zinc substituted nanocrystalline spinel cobalt ferrite: Structural and magnetic studies

Zinc doped cobalt ferrite spinel nanoparticles were prepared by the microwave combustion method. All the samples were characterized by using X-ray diffraction technique (XRD), Scanning Electron Microscopy, energy dispersive X-ray analysis, UV–visible diffuse reflectance spectroscopy, Fourier transformed infrared (FT-IR) spectroscopy and vibrating sample magnetometry. The XRD patterns confirmed the formation of single phase CoFe₂O₄ inverse spinel structure without impurities. The lattice parameter increased from 8.380 to 8.396 Å with increasing Zn²⁺ fraction. The average crystallite sizes obtained by a Scherrer method varied between 46.22 nm and 30.79 nm. The estimated band gap energy values increases with an increasing zinc fraction (1.88–2.10 eV). The elemental composition of Zn, Co, and Fe was qualitatively obtained from energy dispersive X-ray (EDX) analysis.     

Synthesis and characterization of Manganese doped Tungsten oxide by Microwave irradiation method

The aim of this article is to synthesis tungsten oxide (WO₃) nanoparticle along with Manganese (3 wt% and 10 wt%) by Microwave irradiation method. The physical properties of the synthesized Manganese doped Tungsten oxide materials were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscope (TEM), UV-Diffuse Reflectance Spectroscopy, SEM-EDAX and Photoluminescence studies. The predominant peaks obtained in X-ray diffraction pattern reveal the crystalline nature of the nanoparticles and the structure belongs to Monoclinic for pure and Mn doped WO₃. FTIR analysis shows the presence of Tungsten and oxygen in the synthesis material and verified with EDAX. TEM analysis shows both pristine and Mn doped WO₃ nanopaticles. They are having spherical shaped morphology with average particle size from 35 to 40 nm. UV-DRS revealed that the bandgap energy for pure and Manganese doped WO₃ are discussed in this article. The Scanning Electron Microscope analysis shows the plate like morphology for pure WO₃ and the morphology were decreased by doping Manganese. The defects and oxygen deficiencies were analysed by photoluminescence spectroscopy.     

Enhanced properties for visible-light-driven photocatalysis of Ag nanoparticle modified Bi2MoO6 nanoplates

The visible light driven Bi₂MoO₆ photocatalyst doped with different contents of Ag nanoparticles was successfully synthesized by a combination of hydrothermal and sonochemical methods. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM and TEM) and UV–visible spectroscopy to investigate crystalline structure, morphology, composition and photocatalytic properties. XRD patterns and TEM images of the samples revealed pure phase orthorhombic Bi₂MoO₆ nanoplates without any detection of Ag dopant due to its low concentration and very tiny particle size. TEM images showed that Ag nanoparticles with the size of 10–15 nm were dispersed randomly on the surface of Bi₂MoO₆. The XPS analysis of Ag/Bi₂MoO₆ nanocomposites revealed the presence of additional metallic Ag. Photocatalytic activities of the Ag/Bi₂MoO₆ nanocomposites were evaluated by determining the degradation of rhodamine B (RhB) under visible light radiation. In this research, the 10 wt% Ag/Bi₂MoO₆ nanocomposites showed the best photocatalytic activity. The results suggest that the dispersion of Ag nanoparticles on the surface of Bi₂MoO₆ significantly enhances its photocatalytic activity.     

One step synthesis of ZnO nanoparticles in free organic medium: Structural and optical characterizations

Nano-sized ZnO particles are synthesized by the sol–gel method in aqueous medium without any annealing, ripening treatment or organic additive addition. The structure, morphology, and optical properties of these ZnO nanoparticles are characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Ultraviolet–visible spectroscopy (UV–vis) respectively. The effect of the synthesis temperature on the morphological (shape and size) and optical properties of these nanoparticles have been examined for temperatures varying from 0 to 80 °C. XRD analysis shows that the as-prepared particles crystallize in the Würtzite hexagonal phase even at very low synthesis temperatures. Meanwhile, Transmission Electron Microscopy observations reveal that the particles present a significant change in shape and size as the temperature increases. They take a flower shape, at very low temperatures, a conical or ellipsoidal shape when the temperature is ranging from 20 °C to 50 °C and a rodlike shape with a hexagonal section at elevated temperatures (>50 °C). Moreover, it has been observed that the increasing of the synthesis temperature leads to a net increase in the average particle size. It affects especially the length in the minor axis direction while the length in the major direction (c-axis) remains nearly constant. Optical properties, carried out by spectrophotometric measurements, indicate that increasing the temperature results in lower band gap energy values.     

Direct thermal decomposition synthesis and characterization of hematite (α-Fe2O3) nanoparticles

Hematite (α-Fe₂O₃₎ nanoparticles were prepared via direct thermal decomposition method using γ-Fe₂O₃ as a wet chemically synthesized precursor. The precursor was calcinated in air at 500 °C. Samples were characterized by Thermogravimetric analysis (TGA), X-ray diffraction, Infrared, Scanning electron microscopy, Transmission electron microscopy (TEM) and Photon correlation spectroscopy (PCS). TEM and PCS analyses revealed that the average particle size of the α-Fe₂O₃ nanoparticles synthesized at 500 °C are about 18±2 nm and 50±3 nm for 1 h and 24±2 nm and 82±3 nm for 2 h, respectively. The difference in average particle size determined by PCS and TEM analysis is due to the electrostatic forces between particles, and their agglomeration in PCS analysis. Magnetic properties have been detected by a Vibrating sample magnetometry at room temperature. The α-Fe₂O₃ nanoparticles exhibited a weak ferromagnetic behavior at room temperature.     

Structural properties of size-controlled SnO2 nanopowders produced by sol–gel method

SnO₂ nanoparticles were synthesized by sol–gel method with different sol concentrations and the effect of sol concentration on the structural properties of SnO₂ was investigated. The aim of this work is synthesizing of SnO₂ nanoparticles from SnCl₂·2H₂O (tin (II) chloride dihydrate) precursor to obtain high quality powders for using as Li-ion anode material. For this purpose, during the SnO₂ precursor solution preparation, chloride ions were removed from the solution and then the sol–gel synthesis was applied. Produced SnO₂ nanopowders were characterized by x-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive x-ray spectroscopy (EDS) analyses. TG-DTA and FT-IR analysis were performed on the synthesized sol. Grain size, crystal index and lattice strains of SnO₂ particles were calculated. The results showed that the grain size of particles has increased by the increasing of sol concentration, and the crystallinity has been improved. The smallest crystallite size (6.03 nm) was obtained from the SnO₂ sample of 6 mmole concentration sol and maximum size (9.65 nm) from 14 mmole sol according to W–H analysis.     

Cobalt-doped cerium oxide nanoparticles: Enhanced photocatalytic activity under UV and visible light irradiation

CeO₂ nanoparticles (NPs) were synthesized by coprecipitation using cerium(III) nitrate hexahydrate as the precursor and ethanol as the solvent. Different concentration of cobalt-doped cerium oxide NPs (3mol % and 6 mol %) were prepared by adding various concentrations of cobalt chloride to cerium nitrate. The as-synthesized NPs were characterized through X-ray diffraction (XRD) measurements, ultraviolet (UV)–visible spectroscopy, Photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). XRD results reveal that the as-prepared CeO₂ NPs had a face-centered cubic structure with crystallite size in the range of 5–8 nm. TEM analyses showed that the CeO₂ NPs and Co-doped CeO₂ NPs had a homogenous size distribution (sizes were within 5–12 nm). Band-edge absorption of CeO₂ NPs redshifted upon increasing the Co concentration as compared to undoped CeO₂ NPs. PL spectra reveal a peak shift of CeO₂ emission upon cobalt doping, which were due to an increase in oxygen defects localized between the Ce4f and O2p energy levels (i.e., via formation of Ce³⁺ states). Photocatalytic degradation of methylene blue in aqueous solution under UV and visible (sunlight) irradiation in the presence of pure CeO₂ NPs and of Co-doped CeO₂ NPs was investigated. The efficiency of photocatalytic degradation of CeO₂ NPs increased with the Co concentration both under UV irradiation and under visible light. Co-doped CeO₂ NPs (6 mol%) showed degradation efficiencies of 98% and 89% at 420 min of exposure to UV irradiation and to visible light, respectively.     

Effect of calcination temperature on Cu doped NiO nanoparticles prepared via wet-chemical method: Structural,optical and morphological studies

In the present study, NiO and Cu-doped NiO nanoparticles were successfully synthesized by wet chemical method at room temperature using sodium hydroxide (NaOH) as precipitating agent. The as-prepared Cu-doped NiO powder samples were subjected to three different calcination temperatures such as, 350 °C, 450 °C and 550 °C in order to investigate the impact of calcined temperatures on the phase formation, particle size and band gap evolution. The phase formation and crystal structure information of the prepared nanomaterials were examined by X-ray powder diffraction (XRD). XRD revealed the face-centered cubic (FCC) structure. Average crystalline size of pure and doped samples estimated using Scherer formula was found to be 15 nm and 9 nm respectively. With increase in the calcination temperature from 350 °C to 550 °C for the Cu doped NiO samples the particle size of the nanoparticles was found to increase from 4 nm to 9 nm respectively. The optical study for both pure and doped NiO nanoparticles was performed using an UV–Vis spectrophotometer in the wavelength range of 200–800 nm. The strong absorption in the UV region confirms the band gap absorption in NiO and was estimated from the UV–Vis diffuse reflectance spectra via Tauc plot. Systematic studies were also carried out to study the effect of calcination on the optical transmittance. Samples were also investigated using Raman and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, morphology of the pure NiO and Cu-doped NiO Nanoparticles were examined by scanning electron microscope (SEM).     

Enhanced photoluminescence properties of ZnS:Cu2+ nanoparticles using PMMA and CTAB surfactants

ZnS nanoparticles with Cu²⁺ doping have been synthesized at 80 °C through a soft chemical route, namely the chemical co-precipitation method at air atmosphere. The water soluble PMMA and CTAB were used as capping agents. The nanostructures of the synthesized nanoparticles have been analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), UV–vis and fluorescence spectrophotometer. The sizes of as-prepared nanoparticles are found to be below 3.4–5.2 nm range. Room temperature photoluminescence (PL) spectrum of the undoped sample exhibits emission in the blue region with multiple peaks under UV excitation. On the other hand, in the Cu²⁺ doped ZnS samples enhanced visible light emissions with emission intensities of ∼2 times larger than that of the undoped sample are observed for CTAB capped sample. The phase changes were observed in different temperatures by TG-DTA.     

Structure,cation valence states and electrochemical properties of nanostructured Mn3O4

Nanostructured Mn₃O₄ with an average crystallite of ~10 nm is synthesized by the controlled reduction of potassium permanganate using hydrazine. The phase purity, average crystallite/particle size, morphology and state of agglomeration were studied using X-ray diffraction (XRD), Transmission Electron microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses. Nitrogen sorption studies give a specific surface area of 62 m²/g and also reveal the mesoporous nature. The presence of Mn⁴⁺ ions is inferred from the Fourier Transform Infra-Red (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) studies. The decrease in the c/a ratio obtained from XRD analysis also indicates the presence of Mn⁴⁺ ions. Electrochemical analysis was done on a symmetric capacitor with nanostructured Mn₃O₄ as the active material and 6 M KOH solution as the electrolyte. Cyclic voltammograms revealed pseudocapcitive behavior with specific capacitance values falling sharply with scan rate. The power density and energy density values obtained from chornopotentiograms are fairly large and indicate the potential application in the field of supercapacitors.     

Transition of nanocrystalline In(OH)3 as spherical Indium Oxide nanoparticles embedded platelets

Indium oxide nanoparticles were synthesized by a co-precipitation method using the basic raw materials like Indium (III) Chloride and the precipitating reagent as Ammonium hydroxide. The formation of Indium oxide is highly dependent on temperature. The morphology, structural, particle size, optical and electrical properties of In₂O₃ nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive microscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared radiation (FTIR), UV spectra, Photoluminescence spectroscopic (PL) and Electrical resistance measurements. The results exhibit a crystalline cubic structure in particles, spherical shape, size about 14 nm and optical band gap of 4.20 eV.     

Strontium ferrite nanoparticle study: Thermal decomposition synthesis,characterization, and optical and magnetic properties

Monoferrite strontium ferrite nanoparticles were successfully synthesized in the presence of strontium oxalate, [(SrC₂O₄)], as strontium precursor by using solid-state thermal decomposition method. X-ray diffraction study was used to determine phase purity, crystal structure, and average crystallite size of the strontium ferrite nanoparticles. The electrical conductivity measurement of the sintered sample was carried out at 300 °C. Metal nitrates and oxalate precursor without any solvent or surfactant were used in this method; later, they were decomposed at 850 °C for 2 h in a gas mixture of 85% Ar and 15% H₂. The average diameter of the strontium ferrite nanoparticles was 40 nm. The as-prepared strontium ferrite nanoparticles were characterized extensively by techniques like XRD, transmission electron microscope (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), room temperature photoluminescence (Pl), ultraviolet–visible spectroscopy (UV–vis), and energy dispersive spectrometry (EDS).     

Low temperature molten salt synthesis of YAG: Ce spherical powder and its thermally stable luminescent properties after post-annealing treatment

Spherical YAG: Ce particles were successfully synthesized at 350 °C by the molten-salt method. The effect of temperature and amount of salt on the crystallization and particle size of YAG: Ce were investigated thoroughly. The results demonstrated that the powders prepared at 350 °C in salt to reactant ratio 2:1 were pure YAG: Ce phase with 200–300 nm in particle size. The as-synthesized phosphors were later post annealed at 1200 °C in O₂, air and N₂, respectively. The results showed that the emission intensity of YAG: Ce sensitively depended on the post-treated atmosphere and the phosphor annealed in N₂ showed the highest emission intensities and a good thermal stability.     

Studies on structural,morphological, magnetic and optical properties of chromium sesquioxide (Cr2O3) nanoparticles: Synthesized via facile solvothermal process by different solvents

Chromium sesquioxide (Cr₂O₃) nanoparticles have been successfully synthesized via the facile solvothermal process, by using CrO₃ in different solvents. The as-synthesized nanoparticle sizes are calculated and confirmed to be 25–45 nm, by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The functional groups of the samples were tested by the Fourier transform infrared (FTIR) spectroscopy. Fine and spherical-like morphologies and compositional elements of the products were observed by the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. A weak ferromagnetic (WFM) property was observed for sample by the vibrating sample magnetometer (VSM). The observed band gap values (E_g=4.33–3.54 eV) higher than that of bulk Cr₂O₃ (~3.4 eV) indicated that the particles had been successfully synthesized in the nano region, and measured by ultra-violet visible (UV–vis) absorption spectroscopy. The broad visible emission at ~399 nm, in the photoluminescence spectroscopy revealed the high purity and perfect crystallinity of the samples.     

Photocatalytic degradation of methyl orange and gas-sensing performance of nanosized ZnO

ZnO nanoparticles were synthesized by calcining composites of zinc nitrate and poly(vinyl pyrrolidone) (PVP, molecular weight 30 000) at a mass ratio of 1:2 at 500 °C for 2 h. X-Ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were used to characterize the as-synthesized ZnO nanoparticles. The particles ranged in size from 30 to 50 nm. Infrared spectra of PVP and the PVP+Zn(NO₃)₂·6H₂O composite revealed coordination between the carbonyl (C=O) of PVP and Zn²⁺ of zinc nitrate, which led to a uniform nanoparticle morphology. The gas-sensing properties and photocatalytic performance of the final product were systematically investigated. The results show that the ZnO nanoparticles exhibit both a high response for ethanol detection and excellent photocatalytic activity for degradation of methyl orange under UV irradiation for 30 min.     

Absence of photocatalytic activity in the presence of the photoluminescence property of Mn–ZnS nanoparticles prepared by a facile wet chemical method at room temperature

Mn-doped ZnS nanoparticles (NPs) were prepared with dopants at various concentrations using a facile, simple and inexpensive wet chemical method at room temperature. The physicochemical properties of NPs were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV–vis) and photoluminescence (PL). XRD analysis confirmed formation of ZnS with zinc blende structure and average crystallite size of about 2 nm. TEM analysis revealed formation of hyperfine NPs with rather good uniformity. The room temperature photoluminescence (PL) spectrum of ZnS:Mn²⁺ exhibited an orange-red emission around 600 nm. The maximum PL intensity was observed for 7.5% Mn doped ZnS. The photocatalytic performance of ZnS:Mn²⁺ was successfully demonstrated for degradation of three different model dyes (i.e. Rhodimine B (Rh. B), Bromocresol Green (BCG) and Bromochlorophenol Blue (BCB)). The results revealed that not only was there a remarkable difference in photocatalytic performance of Mn doped ZnS for all three different dyes at different dopant concentrations but also photocatalytic activity was decreased by Mn doping.     

Influence of annealing temperature on the structural and optical properties of nanocrystalline zirconium oxide

Nanocrystalline zirconium oxide powder was prepared by sol-gel method using zirconyl chloride octahydrate (ZrOCl₂·8H₂O) and ethylenediaminetetraacitic acid (EDTA) in ammonium hydroxide (NH₄OH) solution. The as-synthesized complex product was annealed at 650 °C, 750 °C and 850 °C for 2 h to get fine ZrO₂ powder. These samples were further analyzed by Scanning electron microscopy (SEM), X- ray diffraction (XRD), Energy-dispersive X- ray spectroscopy (EDX), UV-vis analysis, Fourier transform infrared (FT-IR) spectroscopy, Photoluminescence spectroscopy (PL) and Raman Spectroscopy to study their structural and optical properties. The structural studies revealed that nanocrystalline ZrO₂ powder exhibits monoclinic phase with variation in crystallite size with annealing temperature. The UV–vis absorption band edge of ZrO₂ decreases from 514 nm to 451 nm as annealing temperature rises from 650 °C to 750 °C. It seems that the drastic reduction in band gap energy may be one of the novel unexpected characteristics of ZrO₂. The FTIR analyses further confirmed the formation of nanocrystalline monoclinic ZrO₂. PL analysis revealed the novel emission peaks at 305 and 565 nm. The Raman spectroscopy confirmed the transformation of amorphous zirconium hydroxide to m-ZrO₂ with increase in temperature from 650 °C to 850 °C.