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.     

Effect of Ce doping on microstructural,morphological and optical properties of ZrO2 nanoparticles

Pure and Ce doped ZrO₂ nanostructures have been synthesized by the microwave irradiation method. The prepared nanoparticles were characterized by various analytical techniques like Thermogravimetric and Differential Thermal Analysis (TG–DTA), X-Ray Diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrum (EDS) and Transmission Electron Microscopy (TEM). The XRD pattern of Ce doped ZrO₂ nanoparticles have been confirms that the tetragonal structure. TEM observations indicated that the average particle size of the pure ZrO₂ some particles spherical shaped and some particles agglomeration in the range of 16–44 nm. Whereas on addition of Ce agglomeration in the range of 32–56 nm. The pure ZrO₂ and Ce doped ZrO₂ nanoparticles were further characterized for their optical properties by UV–vis reflectance spectra (DRS) and Photoluminescence (PL) spectroscopy.     

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.     

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.     

Optical properties of undoped and cobalt doped ZnS nanophosphor

In the present study, the optical properties of ZnS and cobalt (Co) doped ZnS nanoparticles were investigated at room temperature. ZnS and ZnS:Co nanophosphors were prepared through chemical route, namely the chemical precipitation method and the formation of the nanoparticles were confirmed by X-ray diffraction and field emission scanning electron microscope (FESEM). Band gap energy of the prepared samples is determined by using a UV–vis–NIR spectrophotometer. The photoluminescence property of ZnS and ZnS:Co sample is determined by fluorescence spectroscopy. The sizes of as prepared nanoparticles are found to be in the 8–9 nm range. The FESEM morphology shows the formation of nanostructure of ZnS samples. The value of optical band gap has been found to be in the range 4.30–4.03 eV. 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, Co²⁺ doped ZnS samples show enhanced visible light emissions under the same UV excitation wavelength of 310 nm.     

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).     

Optical properties of ZnS nanoparticles prepared by high energy ball milling

In this work, we synthesized zinc sulfide (ZnS) nanoparticles by the mechanochemical route using zinc acetate and sodium sulfide as source materials in a high energy planetary ball mill at rotation speed of 300 rpm with ball to powder ratio 5:1 for 30–120 min. Powder samples were collected at duration of 30 min for different analyses. The milled powders were washed with methanol to remove impurity and dried at 50 °C for 2 h. ZnS nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, UV–vis–NIR spectrophotometry and fluorescence spectrophotometry. The crystallite size of synthesized ZnS nanoparticles is found to be approximately 2 nm. The optical band gap of the ZnS nanoparticles is found to be in the range of 4.71–5.17 eV. Room temperature photoluminescence (PL) spectra of the samples exhibit blue-light emission using UV excitation wavelength of 280 nm.     

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.     

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.     

Optical studies of nano-structured La-doped ZnO prepared by combustion method

Coral-shaped nano-structured zinc oxide (ZnO) was successfully synthesized and La-doped via a facile combustion process using glycine as a fuel. The auto-ignition (at ∼185 °C) of viscous reactants zinc nitrate and glycine resulted in ZnO powders. Hexagonal wurtzite structure of pure and doped ZnO powder was confirmed by X-ray powder diffraction analysis. The transmission electron micrograph shows that the nano-structured ZnO is coral-shaped and possess maximal pore (∼10–50 nm pore size) density in it and the grain size is approximately about 15 nm. Addition of dopants subsequently alters the structural and optical properties which were confirmed by UV–VIS studies.     

Effects of graphite on the synthesis of 1-D single crystal In2O3 nanostructures at high temperature

This study investigated the effects of graphite powder on the growth mechanisms of one-dimensional (1-D) single-crystal indium oxide (In₂O₃) nanostructures. The study was conducted using a chemical vapor deposition (CVD) method at 1000 °C; In₂O₃ and graphite powder mixed with In₂O₃, with a weight ratio of 1:1, were used as the source material, while 2 nm-thick n-type silicon (100), coated with a gold catalyst, was used as a substrate. It was observed that nanostructures grew via a Vapor-Liquid-Solid (VLS) growth mechanism when only In₂O₃ was used, but grew via both VLS and Vapor-Solid (VS) growth mechanisms when graphite powder was used with the In₂O₃. The morphology and crystal structures of the nanostructures grown were investigated using X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HR-TEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion X-Ray Spectroscopy (EDS). At room temperature (RT), all the nanostructures showed photoluminescence (PL) spectra at a wavelength of 367 nm in the UV-emission region and at wavelengths of 470 and 630 nm in the visible region.     

Surfactant free hydrothermally derived ZnO nanowires,nanorods, microrods and their characterization

ZnO nanowires, nanorods and microrods have been prepared by an organic-free hydrothermal process using ZnSO₄ and NaOH/NH₄OH solutions. The powder X-ray diffraction (PXRD) patterns reveal that the ZnO nano/microrods are of hexagonal wurtzite structure. The Fourier transform infrared (FT-IR) spectrum of ZnO powder shows only one significant spectroscopic band at around 417 cm^?1 associated with the characteristic vibrational mode of Zn–O bonding. The thickness 75–300 nm for ZnO nanorods and 0.2–1.8 μm for microrods are identified from SEM/TEM images. UV–visible absorption spectra of ZnO nano/microrods show the blue shift. The UV band and green emission observed in photoluminescence (PL) spectra are due to free exciton emission and singly ionized oxygen vacancy in ZnO. Finally, the mechanism for organic-free hydrothermal synthesis of the ZnO nano/microrods is discussed.     

Optimising conditions for the growth of nanocrystalline ZnS thin films from acidic chemical baths

The growth of nanocrystalline zinc sulfide thin films onto glass substrates by chemical bath deposition has been optimized at acidic pH. Powder X-ray diffraction (p-XRD) confirms the deposition of sphalerite, the cubic phase of ZnS. The crystallite size calculated by Scherrer equation was found to be 4.0 nm. Scanning Electron Microscopy (SEM) show clusters of spherical nanoparticles uniformly distributed over the surface of the glass substrates. Energy Dispersive X-ray (EDX) analysis of the deposited thin films show the zinc to sulfur ratio close to 1:1. The observed band gap (3.78 eV) of the deposited thin films is higher than that reported for cubic phase of bulk ZnS (3.54 eV) as expected due to nano-size crystallites. Binding energies calculated by X-ray Photoelectron Spectroscopy (XPS) confirm the material as ZnS and the photoluminescence measurements show the blue shift in emission maximum.     

Synthesis and characterization of ZnS/ZnO/CdS nanocomposites

Water-soluble ZnS/ZnO/CdS (0.1–0.5 M) nanocomposites were successfully synthesized by the chemical precipitation method in air. X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–vis), photoluminescence (PL) and thermo gravimetric-differential thermal analysis (TG-DTA) were used to characterize the synthesized products. It is found that the ZnS/ZnO/CdS (0.1–0.5 M) core–shell nanocomposite is cubic and hexagonal mixed structure. TEM results showed the prepared nanocomposites are monodispersed and uniform in size. It is confined within 4.3–5.6 nm range. UV–vis absorption spectra were confined growth process of multi shells on ZnS. It showed a red shift with respect to the shells thickness. Fluorescence measurement showed the emission band which exists in the visible region. Stability and phase transition were identified by TG-DTA analysis. The results show an improved florescence property, indicating their potential applications in biological labeling.     

Preparation,structural and optical investigations of ITO nanopowder and ITO/epoxy nanocomposites

Indium Tin Oxide (ITO) nanopowder was synthesized by a sol–gel method. It was characterized by X-ray diffraction (XRD) and transmission electron microscopy. ITO/epoxy nanocomposites (ITO–EP-NCs) were prepared by mechanically dispersing the as-prepared ITO nanopowder into epoxy matrix. The XRD patterns show structural changes depending on ITO content. The interdependence of structural, morphological, optical properties and the dispersed concentration of ITO nanoparticles were investigated. The UV–visible absorption spectra revealed that the ITO–EP-NCs exhibit enhanced UV light absorption properties and wide absorption bandwidth ranging up to 400 nm from 2 wt% ITO loading. Thus, it indicated that UV and IR-shielding properties have been improved with the incorporation of ITO nanoparticles into the epoxy matrix.The gap energy of epoxy matrix was reduced by adding the ITO-NPs, leading to the improvement of its electrical conductivity. Indeed, the AC electrical conductivity of ITO–EP-NCs showed a critical percolation threshold p_c=0.21 wt% ITO. For low loading (<2 wt% ITO), the ITO–EP-NCs have combined good transparency in the visible range and enhanced electrical conductivity, which are required for optoelectronics devices.     

Enhanced visible light-photocatalysis by hydrothermally synthesized thallium-doped bismuth vanadate nanoparticles

Thallium-doped (1.5, 2.3 and 19.3 at%) bismuth vanadate (BiVO₄) and pristine BiVO₄ nanoparticles were hydrothermally synthesized. They were characterized by powder X-ray and selected area electron diffractometries, high resolution scanning electron and transmission electron microscopies, and energy dispersive X-ray, Raman, UV–visible diffuse reflectance and photoluminescence spectroscopies. Tl-doping reduces the band gap energy and recombination of charge carriers. The visible light photocatalytic activity of 19.3% Tl-doped BiVO₄ nanoparticles is larger than those of the other Tl-doped BiVO₄ and pristine BiVO₄ nanoparticles. The synthesized Tl-doped BiVO₄ nanoparticles displaying enhanced photodegradation of dye could find potential applications as visible light photocatalyst for the abatement of various organic pollutants.     

Tunable emission property of biotin capped Gd:ZnS nanoparticles and their antibacterial activity

Gd doped ZnS nanoparticles have been successfully fabricated by a microwave irradiation method whose surface was passivated with biotin at different concentration. The structural property was investigated by characterizing the samples with the help of X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). Energy dispersive spectroscopy (EDS) measurement showed the existence of Gd ion in the Gd-doped ZnS nanoparticles. Optical confirmation was done with the help of UV–visible and photoluminescence spectroscopy. Diffraction data confirmed the zinc blend structure for all the samples with grain size of 5.8 nm for uncapped and 3–4 nm for capped nanoparticles with varying concentration of biotin. Spherical shape with 7 nm (uncapped) and 4 nm (capped) were definite from TEM images. HRTEM images and SAED patterns with bright circular rings designated the cubical environment of these nanoparticles. Emission bands in the blue, green and red regions were observed for both the samples, which was blue shifted in case of capped nanoparticles with increased intensity. Enhanced luminescence property was observed in the case of capped Gd:ZnS nanoparticles when compared to uncapped and thus can be of biomedical uses. Notably these biotin capped Gd:ZnS nanoparticles proved to be a potential antibacterial agent against different pathogenic bacterial strains, which showed maximum zone of inhibition at concentration of 10 µg/ml. The bioactivity sums up that this surface passivated nanoparticle emerges as a new class of antibacterial agent.     

Synthesis,characterization and optical properties of mercury sulfides and zinc sulfides using single-source precursor

HgS and ZnS nanostructures were prepared by using two different methods. HgS nanodendrites and ZnS nanospheres were synthesized via hydrothermal decomposition of [M(TSC)₂]Cl₂ complex (M=Hg, Zn and TSC=thiosemicarbazide), without any surfactant. And using oleylamine (C₁₈H₃₇N) and TPP (C₁₈H₁₅P) as surfactant, HgS nanoparticles with an average diameter of approximately 20–40 nm were synthesized by thermal decomposition of the [Hg(TSC)₂]Cl₂, whereas the coalesced particles and bulk structures were formed by thermal decomposition of [Zn(TSC)₂]Cl₂. To study the crystalline structure, size, morphology and composition of the products, characterization techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy were employed. Ultraviolet visible (UV–vis) absorption and photoluminescence (PL) spectroscopy exhibited optical properties of nanostructures.     

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).     

Characterization of zinc sulfide (ZnS) nanoparticles Biosynthesized by Fusarium oxysporum

A variety of chemical and physical procedures could be used for the synthesis of metal sulfide nanoparticles. However, these methods suffer from some disadvantages including the use of toxic solvents, generation of hazardous by-products, and high energy consumption. In this work, zinc sulfide (ZnS) nanoparticles were synthesized through an environmentally and economically friendly method using the fungus Fusarium oxysporum. The ZnS nanoparticles were characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Fluorescence spectroscopy. The obtained results demonstrated the presence of ZnS nanoparticles. Transmission electron microscopy (TEM), also determined their morphology as spherical, and their average size to be about 42 nm.