Narrow Results

Lead iodide (PbI${}_2)$ nanoparticles in silica have been synthesized using the sol–gel method. The aqueous method of synthesis has been used for undoped PbI₂ nanoparticles. These nanoparticles have been stabilized using thioglycerol acting as the capping agent. The narrow-sized PbI₂ nanoparticles have been obtained, which are characterized by size-dependent properties. The PbI₂ nanoparticles have been characterized and their properties have been investigated by using various experimental techniques like Ultraviolet–Visible (UV–Vis) Absorption Spectroscopy, X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Photoluminescence (PL), Atomic Force Microscopy (AFM), etc. The lateral dimension of PbI₂ nanoparticles in silica varies from 9 Å to 27 Å. PbI₂ thin films were deposited on silicon wafers by using the dip coating method and analyzed by using various characterization techniques like Scanning Electron Microscopy (SEM), Energy Dispersive Analysis by X-rays (EDAX), Mapping, etc. The aim of this work is to synthesize PbI₂ nanoparticles with a size less than or comparable to the Bohr diameter of the exciton. The characterization results showed that the cluster size increases with the increasing film thickness and by the heat treatment in air atmosphere. The PbI₂ nanocrystals embedded in silica films have been studied in this paper. The PbI₂ nanoparticles and the PbI₂ sol–gel thin films can be used in optoelectronic device applications and chemical industrial applications. To the best of our knowledge, there are no studies on the synthesis of PbI₂ nanoparticles in silica using the sol–gel route and on the preparation of PbI₂ thin films using the dip coating method.

Nanodiamonds (NDs) have unique optical and mechanical characteristics, surface chemistry, extensive surface area and biocompatibility, and they are nontoxic, rendering them suitable for a diverse range of applications. Recently, NDs have received significant attention in nano-biomedical engineering. This review discusses the recent advancement of NDs’ biomedical engineering, historical background, basic introduction to nanoparticles and development. We summarize NDs’ synthesis technique, properties and applications. Two methodologies are used in ND synthesis: bottom-up and top-down. We cover synthesis methods, including detonation, ball milling, laser ablation, chemical vapor deposition (CVD) and high pressure and high temperature (HPHT); discuss the properties of NDs, such as fluorescence and biocompatibility. Due to these properties, NDs have potential applications in biomedical engineering, including bioimaging, biosensing, drug delivery, tissue engineering and protein mimics. Further, it provides an outlook for future progress, development and application of NDs in biological and biomedical areas.

Nanostructured MgO powders have been synthesized using chemical methods. Ammonium oxalate and Magnesium sulphate were used as the precursor materials. The weight ratios of the raw materials (ammonium oxalate/Magnesium sulphate) were 0.9, 1, 1.1, 1.2, 1.3, and 1.4. As a result of chemical reaction (between them), Magnesium oxalate was synthesized. Produced samples were analyzed by XRD and SEM. The results show that the best ratio (for ammonium oxalate/Magnesium sulphate) is 1.4. Produced Magnesium oxalate powder was heated at 450 and 550°C. The final product was MgO nanopowder. XRD studies indicate that the highest ratio of MgO was observed in the specimen heated at 450°C.

The present paper attempts as how the pigments comprising of nano-sized hematite particles deposited on mica surfaces in optimum conditions offer an excellent pearlescent properties. To record the influencing parameters on the synthesis process, response surface methodology (RSM) technique was used where temperature of reaction, synthesis time and concentration of urea were selected as variable parameters. Taking into account colorimetric parameters, the whole process was then analyzed by "Design Expert" software that finally gave following optimum factors: reaction temperature=82.02°C, synthesis time=11.98 h, urea concentration=37.5 g/l. Once the above optimum parameters selected, seemingly, the spherical hematite particles of about 60 nm in diameter are deposited uniformly on mica surfaces.

A soft approach has been described for the formation of α–Fe₂O₃ nanorods by simple reaction of iron with water at a very low temperature range of 100–300°C. It is shown that the nanorods have diameters ranging from 50–80 nm, and their typical lengths are in the range of 5–10 μm. The chemical composition and crystalline structure of nanorods were investigated by various characterization techniques. The initial formation and subsequent growth of α–Fe₂O₃ nanostructures may be explained by the iron metal corrosion mechanism.

With the advent of nanotechnology, methods of synthesis have attained immense importance since it governs particle size of the materials. In this paper, we report synthesis of CaZrO₃ by simple and energy efficient method that produced ultra fine powder having particle size in the nanometers. Synthesis of CaZrO₃ was carried out using corresponding metal nitrates and mixed fuels i.e., glycine and urea at a temperature less than 500^°C. The reaction was highly exothermic in nature. The product obtained was voluminous and foamy. The as synthesized CaZrO₃ is crystalline in nature. It required no further heating. The compound was indexed using standard indexing procedure and the lattice constants matches completely with those reported in the literature. Differential Thermal Analysis (DTA) and Thermo Gravimetric Analysis (TGA) results shows that the material is highly stable internally during the whole range of temperature studied i.e., up to 1000^°C. The powder density of the material was calculated to be 5.6393 gcm^-1. BET surface area was found to be 11.505 m²/g. The particle size was calculated using density and BET surface area values. The particle size of the as synthesized CaZrO₃ was found to be 92 nm. The product was further characterized using Scanning Electron Microscope and electrical conductivity.

Bimetallic structure of nanoparticles is of great interest due to their extraordinary properties, especially in combining the specialty of the core and its shell. This work reports the effect of pH on the synthesis of Ni–Au (nickel–gold) bimetallic nanoparticles. The synthesis involves a two-step process where Ni nanoparticles were first synthesized using polyol method with hydrazine as the reducing agent. This was followed by the process of reducing to Au in the solution containing pre-prepared Ni to form Ni–Au bimetallic nanoparticles using sodium citrate as the reducing agent. The results obtained from Transmission Electron Microscopy (TEM) show that the process can possibly produce either core-shell structure, or mixture of Ni and Au nanoparticles. Magnetic property of core-shell structure investigated using Vibrating Sample Magnetometer (VSM) demonstrated typical characteristic of ferromagnetic with an increased magnetization as compared to Ni nanoparticles. The saturation magnetization (M_s) and coercivity (H_c) were obtained as 19.1 emu/g and 222.3 Oe, respectively.

This study reports the effective synthesis of multilayered graphene sheets via microwave atmospheric pressure plasma. This innovative approach streamlines and expedites graphene production and other carbon nanostructures, eliminating the need for catalysts, solvents, or complex processing conditions. Ethanol is directly injected into a microwave-generated argon plasma plume, leading to the formation of graphene. Raman spectroscopy revealed characteristic peaks (2D, G, and D bands) confirming graphene composition, with defects indicated by the D band. X-ray diffraction analysis supported these findings, indicating a broad peak at 25^∘ corresponding to the (002) plane, affirming a multi-layered graphene structure. Scanning electron microscopy exhibited crumpled, randomly oriented graphene sheets, albeit with uneven structures suggesting impurity incorporation. The presence of defects was quantified through the intensity ratio of the D to G band (I_D/I_G) in Raman spectroscopy, revealing a value of 0.80, signifying the presence of defects in the synthesized graphene. The 2D to G band intensity ratio (I_2D/I_G) suggested the existence of 7–10 graphene layers, highlighting the need for further optimization for enhanced graphene quality and purity.

The detonation of carbon- or nitrogen-containing explosives not only produces powerful shock waves but also provides elemental building blocks and a unique high-pressure and high-temperature physical environment for the construction of various nanostructures. This review highlights the situation and key progresses in the detonation approach towards diamond nanoparticles, graphitic carbon nanotubes, fullerene molecules, and gallium nitride nanocrystals. Further extension of the peaceful-use detonation applications and rational reactor design are also proposed.

An easy and novel approach is described for the formation of zinc oxide nanorods by simple reaction of zinc metal with water in a very low temperature range of 25–75°C. It offers a facile and fast route for large scale production of zinc oxide nanorods without catalysts. The diameters of the nanorods range from 30–120 nm with several micrometers in length. The resulting nanorods have been comprehensively characterized by Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive Analysis (EDX). A plausible mechanism is proposed for the formation of these nanorods and it is expected that this synthetic technique can be extended to obtain other oxides. This will contribute to broadening the range of materials.

In this work, CdSe quantum dots (QDs) were synthesized using a microwave activated reaction between NaHSe and CdSO₄ in the presence of thioglycolic acid (TGA) as capping molecule and then using a one-pot method, ZnS shell was grown subsequently around CdSe cores by a room temperature reaction based on the photo-sensitivity of Na₂S₂O₃ dissociation. Synthesized QDs were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. All these analyses confirmed the formation of CdSe QDs and successful growth of ZnS shell around CdSe cores.

Sn precursor layer was evaporated on a glass substrate by an electron-beam evaporation method and followed by selenization using Se powder. SnSe film was successfully prepared by adjusting the selenization temperature and selenization time. The phase, microstructure and optical properties of the SnSe films were studied by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, and UV-Vis-NIR spectrophotometer. The results demonstrated that the pure phase polycrystalline SnSe films with a band gap of 0.93 eV could be prepared by selenizing at 450${}^{\circ }$C for 60 min. Under the irradiation of a 980 nm laser with a power of 2 mW/cm², photoelectric response characteristics of the SnSe films were tested, and the response time and recovery time of the prepared film were 62 ms and 80 ms, respectively, indicating that the SnSe film had a large application prospect in near-infrared light detection.

The WC–Co nanocomposites were synthesized by using a polymer precursor such as polyacrylonitrile, which severs as an in situ carbon source. The WC–Co nanocomposites formed are characterized by X-ray diffraction and electron microscopy. Nearly pure WC–Co nanocomposites with a particle size in the range of 60–80 nm have been obtained. The use of H₂ atmosphere enhanced the carbide formation and in turn reduced the reaction time (at high temperature). The phase purity of the products is strongly influenced by the processing conditions such as the firing temperature, time and atmosphere. This suggests that the process parameters have to be optimized before scaling up the process for commercial production.

We report a novel method to synthesize multiwalled carbon nanotubes (MWNTs) in large scale at 470°C. TEM and Roman spectra analysis show that dominating graphite crystalline coexists with amorphous carbon in MWNTs. XRD and TGA results suggest that fcc cobalt plays a catalytic role in the growth process of MWNTs, which exists and stable inside the carbon layers of MWNTs. The synthesis method is simple and can easily ensure adequate stability and reproducibility. Therefore the method is possibly suited to industrialized synthesizing process of MWNTs due to these advantages.

Single-sided ZnO nanocombs have been synthesized by thermal evaporation of Zn powders at 440°C through a vapor–solid (VS) process. The stem ribbon of the as-synthesized nanocomb takes a growth direction of , and its top/bottom surfaces are . The nanoteeth grow epitaxially out of the stem ribbon along [0001]. Such a low temperature process may be useful in future device fabrication.

The magnetic properties of nanocrystalline powders of Ni_0.5Zn_0.5Fe₂O₄, synthesized at low temperatures, by a combustion method, have been investigated. Different powders containing crystallites of comparable average size, obtained by varying the synthesis conditions, show a large difference in the superparamagnetic blocking temperature due to the wide difference in the size distribution. The ferrite nanoparticles show large Curie temperature enhancement up to ~ 100 K, when compared to that of the bulk.

The present study elucidates the synthesis of magnesium ferrite magnetic nanocrystallites via hydroxylation–condensation reaction followed by an auto-combustion process. Nanocrystallites with diameter of 3–7 nm were successfully formed via this method. The ignition temperature of the redox reaction was apparently improved to 200°C by the modification of the pH of the metal aqueous solution. The crystallite size was altered by varying the hydrolysis parameters. The XRD analysis of the as-synthesized powder confirms the formation of a single-phase MgFe₂O₄ spinel structure. Importantly, the crystalline particles were obtained at low temperature without further calcination. The thermodynamic behavior of the precursor was characterized by DTA-TG. TEM observations showed the morphology and crystal structure of the nanocrystallites.

Nanosized metal hydroxides are synthesized in the presence of Poly(vinyl alcohol). Polymer controls the size and growth of the nanometal hydroxides. PVA-assisted synthesis of metal hydroxides is characterized by FTIR, XRD, TGA, and HRTEM methods. This method of synthesis is an eco-friendly and economically viable method.

Here, we report single step synthesis of hydrophobic and hydrophilic Fe₃O₄, ZnO, CoO and Y₂O₃:Eu nanoparticles via thermal decomposition of different organometallic complexes in oleylamine (OM) and tri(ethyleneglycol) (TREG) media, respectively. The crystal structure of the as-prepared nanoparticles is identified using X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Morphology of the nanoparticles is determined by transmission electron microscopy (TEM) while the magnetic properties are measured using vibrating sample magnetometer (VSM). Thermolysis of appropriate precursors in OM and TREG medium are very capable of producing the highly dispresed hydrophobic and hydrophilic nanoparticles with diverse morphologies.

Ferromagnetic nanoparticles when dispersed in a dielectric ceramic matrix offer a new series of percolation composites with a metal-semiconductor or insulator interface that tailors the functional properties. In this purview, ZrO₂ of a high dielectric constant (ε_r) is stabilized in a cubic (c) polymorph by incorporating CrO₂ of strongly ferromagnetic nanoparticles. A selective composition 20CrO₂–80ZrO₂ is synthesized after heating a polymer precursor with glycerol at 500°C–800°C in air for 2 h. Broadening of X-ray diffraction peaks reveals Cr⁴⁺:c-ZrO₂ with an average crystallite size 5 nm in the 500°C heated sample and that is grown to 8 nm on increasing the temperature to 800°C. They occur as bundles of thin platelets in electron microscopic images. Both the samples have ferromagnetic hysteresis loops with 794 and 211 Oe of coercivities, respectively. Variations of ε_r-value and the power loss are studied as a function of frequency f (50 Hz–100 kHz range) on cold-pressed pellets at selective temperatures, in the 30°C–500°C range, in describing the effects of the magnetic species.