The role of albumen (egg white) in controlled particle size and electrical conductivity behavior of zinc oxide nanoparticles

The size controlled zinc oxide nanoparticle is synthesized in the isothermal evaporation method with albumen (egg white). This method is simple and cost effective for synthesis of ZnO nano powder. The egg white foam was assisted to increase the reaction rate and produce the zinc oxide nano powder. This method helps to attain the particle size in the range 13–28 nm. The results from X-ray diffraction patterns and TEM micrograph confirmed the formation of nano crystalline phase with particle size ranges from 13 nm to 28 nm. The samples were further analyzed by using Fourier transform Infrared spectroscopy (FT-IR), photoluminescence spectrum (PL), thermogravimetric analysis (TGA) and Resistivity measurement. The less time consumption in isothermal evaporation process was one of the significant roles for large scale zinc oxide nano powder production.     

Preparation and characterization of nanoboron by cryo-milling

Cryo-milling of coarse micron grade elemental boron powder was investigated for possible generation of nanosized boron powder. Process parameters were optimized for the least contamination and least particle size. The as-milled powders were characterized by scanning and transmission electron microscopy (SEM/TEM) and x-ray diffraction (XRD) for powder morphology, average particle size, and phase analysis. The particle size and surface area were also estimated using dynamic laser scattering (DLS) and BET techniques to correlate with the performance of the material. Thermo-gravimetric and differential thermal analysis (TG-DTA) studies were performed to ascertain mass change and energy release in unmilled and milled powder. The average particle size of boron powder after 9 h of cryo-milling was<100 nm. The cryo-milled powder was made air-stable and dispersible in JP10 fuel by coating it with ligand through the mechanical milling method. The TOPO (tri-n-octyl phosphine oxide) coated nano boron powder exhibited dispersion stability for a week.     

Utilization of biowaste eggshells to synthesize nanocrystalline hydroxyapatite powders

Nano hydroxyapatite (HA) powder was successfully synthesized from biowaste chicken eggshells. The nanopowders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), particle size distribution (PSD) analyzer, and Fourier transform infrared spectroscopy (FT-IR) techniques. Selected area electron diffraction (SAED) analysis during TEM showed the particles to be polycrystalline in nature. The resulting HA powder exhibited an average size of ~ 35 nm with a narrowly distributed particle size range from 5 to 90 nm. XRD and FT-IR analysis showed that the powders produced were of high purity. The present study provides a simple sol–gel precipitation method to obtain nano HA powders of high purity from biowaste chicken eggshells.     

Effect of solvents on the synthesis of nano-size zinc oxide and its properties

The effect of the solvents on particle size and morphology of ZnO is investigated. The optical properties of nano ZnO were studied extensively. During this study, zinc oxalate was prepared in aqueous and organic solvents using zinc acetate and oxalic acid as precursors. The thermo-gravimetric analysis (TGA/DTA) showed formation of ZnO at 400 °C. Nano-size zinc oxide was obtained by thermal decomposition of aqueous and organic mediated zinc oxalate at 450 °C. The phase purity was confirmed by XRD and crystal size determined from transmission electron microscopy (TEM) was found to be 22–25 nm for the aqueous and 14 –17 nm in organic mediated ZnO. Scanning electron microscope (SEM) also revealed different nature of surfaces and microstructures for zinc oxide obtained in aqueous and organic solvents. The UV absorption spectra showed sharp absorption peaks with a blue shift for organic mediated ZnO, due to monodispersity and lower particle size. Sharp peaks and absence of any impurity peaks in photoluminescence spectra (PLS) complement the above observations.     

Preparation of zinc oxide nanorods by microwave assisted technique using ethylene glycol as a stabilizing agent

Zinc oxide nanorods have been synthesized by microwave assisted method using zinc nitrate, ethylene glycol and sodium hydroxide as a precursors. The material was characterized by XRD, SEM, EDAX and UV–Visible techniques. XRD analysis revealed all the relevant Bragg’s reflections for wurtzite (hexagonal phase) structure of zinc oxide. The average particle size was obtained 34 nm from the Williamson–Hall plot. The value of particle size determined from XRD was in good agreement with the SEM and TEM results. The direct optical band gap was found to be 3.13 eV.     

Economical synthesis of nano alumina powder using an aqueous sol-gel method

Nano alumina powder can be widely used in the fields of electronics, catalyst supports and high temperature applications. In the present article, a nano Al₂O₃ powder was synthesized by a simple aqueous sol-gel method using inexpensive AlCl₃·6H₂O and Al powder as raw materials. It was shown that the gel calcined at 1100 °C resulted in the formation of a crystalline α-Al₂O₃ nano powder. It had a particle size distribution ranging from 32 to 100 nm after heat treatment at 1200 °C.     

Physical and electrochemical study of cobalt oxide nano- and microparticles

Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co₃O₄ was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 μm (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles.     

Photocatalytic degradation of selected pharmaceuticals using green fabricated zinc oxide nanoparticles

Heterogeneous photocatalysis is one of the popular alternative treatment methods for wastewater. It utilizes semiconductor material as the catalyst and metal oxide such as zinc oxide nanoparticles (ZnO NPs), emerged as the commonly used catalyst. In this study, a series of biogenic ZnO NPs was fabricated through precipitation method with pullulan as the biomaterial. The amount of zinc salt in the presence of pullulan was varied to study its impact on the generated ZnO NPs. The results showed that without pullulan, the average particle size of ZnO NPs obtained was 110.86 nm. With 0.84 M zinc salt in 50 g/L of pullulan, the ZnO NPs average particle size significantly reduced to 58.13 nm. The surface area of all synthesized ZnO NPs ranging from 14.84 to 19.99 m² g^?1. The photocatalytic activities of all synthesized ZnO NPs were evaluated through the photodegradation of two drugs, amoxicillin (AMX) and paracetamol (PCT). Through the comparison of drugs’ photodegradation with all synthesized ZnO NPs, ZnO NPs produced with 0.67 M zinc salt in 50 g/L of pullulan showed the highest degradation percentage of 85.7% and 96.8% for AMX and PCT respectively. The best photodegradation conditions for the drugs were 30 ppm drugs concentration, pH 9 (for AMX) and pH 5 (for PCT) and 50 mg catalyst dosage. Based on these results, biogenic ZnO NPs has high potential to be used in the treatment of pharmaceutical wastewater.     

Synthesis and photocatalytic activity of nano-sized iron oxides

Nano-sized iron oxide powder with average crystallite sizes 35, 100 and 150 nm was prepared by thermal evaporation and co-precipitation techniques. The synthesized powders were characterized by X-ray diffraction analysis technique, transmission electron microscope (TEM) and scanning electron microscope (SEM). The prepared powders were tested as catalysts for the photo catalytic decomposition of Congo red dye. The effect of crystal size of iron oxides on the rate of decomposition of Congo red dye was investigated in visible light as well as in the absence of light. The experimental results show that both iron oxides with crystallite size 35 and 150 nm cause complete decomposition of Congo red dye while iron oxide particles with crystallite size 100 nm were unable to decompose the dye.     

Application of the gas phase condensation to the preparation of nanoparticles

The evaporation of materials in ultra-high vacuum leads to the growth of thin films on appropriated substrates. In the presence of an inert gas (pressure above 10⁻¹ Torr), the evaporated materials lose kinetic energy by collisions with the inert gas molecules in the gas phase and condense in the form of nanometric size crystallites that can be collected on the substrate as an ultrafine powder. In the present communication, we discuss how thin film deposition methods can be modified to collect ultrafine powders instead of continuous films. We describe, with some examples, the use of the gas phase condensation in the preparation of two different types of materials as nanometric powders. On one hand, CdS nanoparticles have been obtained in the form of homogeneous spheres with a mean particle size of 16 nm in diameter. This material, with applications in catalysis and optical devices, has been characterised by UV–VIS Absorption Spectroscopy, Transmission Electron Microscopy and X-ray Diffraction. On the other hand, magnetic nanoparticles of Co have also been prepared as nanostructured materials with an average particle size of 10 nm. Transmission Electron Microscopy, X-Ray Photoelectron Spectroscopy and X-ray Diffraction have been used to characterise this sample. The formation of an interesting material, consisting of Co cores covered by an oxide passivation layer, has been demonstrated.     

ZnO controllable sized quantum dots produced by polyol method: An experimental and theoretical study

Zinc oxide quantum dots were prepared in diethyleneglycol using zinc acetate as a precursor compound and the particle size of the dried powders was determined using the X-ray diffraction method (XRD). It was found that quantum dot size ranges from 4 to 9 nm and is influenced by the initial zinc acetate concentration and the centrifugation speed. Theoretical predictions concerning quantum dot size by the potential morphing method showed good agreement with the measurements from XRD.     

Formation of cubic zinc sulfide nanocrystals in paraffin liquid

A green and cheap route to the production of cubic zinc sulfide nanocrystals is presented. Nanocrystals were synthesized in sole solvent paraffin liquid with zinc oxide, elemental sulfur and oleic acid. Their photophysical properties were investigated by UV-vis absorption and photoluminescence spectra. The temporal evolution of UV-vis spectra showed that the reactions could be terminated after about 5 min growth with a main absorption peak at 267 nm. The typical photoluminescence peaks (excited by 260 nm) were observed at about 285 nm and 397 nm. Transmission electron microscopy and selected area electron diffraction in combination with X-ray powder diffraction indicated the presence of cubic ZnS nanocrystals in good crystallization with the average size of 5.0 nm in diameter.     

Preparation of SnO2 nanoparticles less than 10 nm in size by precipitation using hydrophilic carbon black powder

Tin oxide powder has recently been prepared by a modified precipitation method in which the precipitate is mixed with carbon black powder, a method which offers low cost and mass production. In this study, we prepared tin oxide powder by the modified precipitation method using hydrophilic and non-hydrophilic carbon black powders. When using the hydrophilic carbon black powder, the crystallite size of the tin oxide after firing at 600 °C was 7.5 nm. In contrast, when using the non-hydrophilic carbon black powder, the crystallite size was 18 nm. Thus the crystallite size was shown to depend on the hydrophilicity of the carbon black powder. The smaller crystallite size obtained may be a result of the gel precipitate (stannic acid) particles being dispersed more uniformly on the surface of the hydrophilic carbon black powder than those on the surface of the non-hydrophilic carbon black powder.     

Visible photocatalytic properties of vanadium doped zinc oxide aerogel nanopowder

Vanadium-doped zinc oxide nanoparticles have been synthesized by sol-gel method. In our approach the water for hydrolysis used in the synthesis of nanopowder was slowly released followed by a thermal drying in ethyl alcohol at 250 °C. The obtained nanopowder was characterized by various techniques such as particle size analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence (PL). In the as-prepared state, the powder with an average particle size of 25 nm presents a strong luminescence band in the visible range. From photoluminescence excitation (PLE) the energy position of the obtained PL band depends on the excitation wavelength and this PL band can be also observed under visible excitations. This result is very promising for visible photo catalysis applications, which was confirmed by methylene blue photo-degradation using visible lamp as a light source.     

Synthesis of uniform nano-structured lead oxide by sonochemical method and its application as cathode and anode of lead-acid batteries

This paper discusses the results of a research aimed at investigating the synthesis of nano-structured lead oxide through reaction of lead nitrate solution and sodium carbonate solution by the sonochemical method. At the first, lead carbonate was obtained in a synthesized solution and then, after filtration, it was calcinated at the temperature of 320 °C so that nano-structured lead oxide can be produced. The effects of different parameters on particle size and morphology of final lead oxide powder were optimized by a “one at a time” method. The prepared lead oxide powder was characterized by scanning electron microscopy (SEM), transmission electron spectroscopy (TEM) and X-ray diffraction (XRD). Under optimum conditions, uniformed and homogeneous nano-structured lead oxide powder with more spongy morphology and particle size of 20-40 nm was obtained. The synthesized lead oxide, as anode and cathode of lead-acid batteries, showed an excellent discharge capacity (140 mA h/g).     

Nanocrystalline hydroxyapatite doped with magnesium and zinc: Synthesis and characterization

During recent years, there have been efforts in developing nanocrystalline bioceramics, to enhance their mechanical and biological properties for use in tissue engineering applications. In this research, we made an attempt to synthesize nanocrystalline bioactive hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) ceramic powder in the lower-end of nano-range (2–10 nm), using a simple low-temperature sol–gel technique and studied its densification behavior. We further studied the effects of metal ion dopants during synthesis on powder morphology, and the properties of the sintered structures. Calcium nitrate and triethyl phosphite were used as precursors for calcium and phosphorous, respectively, for sol–gel synthesis. Calculated quantities of magnesium oxide and zinc oxide were incorporated as dopants into amorphous dried powder, prior to calcination at 250–550 °C. The synthesized powders were analyzed for their phases using X-ray diffraction technique and characterized for powder morphology and particle size using transmission electron microscopy (TEM). TEM analysis showed that the average particle size of the synthesized powders were in the range of 2–10 nm. The synthesized nano-powders were uniaxially compacted and then sintered at 1250 °C and 1300 °C for 6 h, separately, in air. A maximum average sintered density of 3.29 g/cm³ was achieved in structures sintered at 1300 °C, developed from nano-powder doped with magnesium. Vickers hardness testing was performed to determine the hardness of the sintered structures. Uniaxial compression tests were performed to evaluate the mechanical properties. Bioactivity and biodegradation behavior of the sintered structures were assessed in simulated body fluid (SBF) and maintained in a dynamic state.     

Direct synthesis of highly crystalline transparent conducting oxide nanoparticles by low pressure spray pyrolysis

In this article, we firstly reported a general preparation method for the production of highly crystallized and single crystalline transparent conducting oxide (TCO) nanoparticles: tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO). Low-pressure spray pyrolysis was applied by means of a modified-atomizer and preheated carrier gas. The effects of pyrolysis pressure, temperature and carrier gas temperature on the size and morphology of the synthesized TCO nanoparticles were systematically investigated. The synthesized TCO nanoparticles were 17 nm large with crystallite size of 8–11 nm. The resistivities of the formed pellets were measured and compared. These results showed that this method successfully produces various TCO nanoparticles using neither dispersing agents nor post-heating treatments, which allows rapid, continuous, single-step preparation.     

A novel route for the synthesis of indium nanoparticles in ionic liquid

In this paper, we report a novel preparation of indium nanoparticles by the reduction of indium chloride in ionic liquid by methanolic solution of NaBH₄. The particles are characterized by means of transmission electron microscopy (TEM), X-ray diffraction and UV-visible studies indicated that the powder consist of the cubic phase of indium. The particle size of indium nanoparticles is in the range of 20 nm mean diameter by Transmission electron microscopy (TEM). The samples display a strong surface plasma absorption band at 231 nm, which indicates that the sample is metal indium and the particle size is less than 20 nm. The thermal analysis of the sample indicate indium not indium oxide. Electrochemical studies show that indium nanoparticles have very good electrical properties.     

Synthesis of nano-TiC powder using titanium gel precursor and carbon particles

The paper presents a novel process for synthesis of nano-size titanium carbide by reaction between titanium bearing precursor gel and nano carbon particles derived from soot at different temperatures in the range of 1300-1580 °C for 2 h under argon cover. The HRTEM studies of TiC powder synthesized by heating at 1580 °C show the presence of cube shaped particles (~ 60-140 nm) and hollow rods (diameter ~ 30-185 nm). The average particle size of crystallites, calculated by Scherer equation is observed to be ~ 35 nm while the surface area-density measurements indicate it to be ~ 113 nm. The surface area decreases with increase in reaction temperature.     

High-purity nano silica powder from rice husk using a simple chemical method

A highly pure, small particle-sized and high surface area nano silica powder was prepared from rice husk using alkali extraction, followed by an acid precipitation method. The composition, phase, morphology, size and surface area of the as-synthesised nano silica powder was investigated by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, particle size analyser and BET surface area analyser. High-purity nano silica powder was obtained by sodium hydroxide (NaOH) purification treatment (0.5, 1, 1.5, 2 and 2.5?N). The high purity of silica (～99.9%) was obtained at 2.5?N NaOH treatment. The pure nano silica powder that is obtained shows an average particle size of ～25?nm with a high-specific surface area (SSA) of 274?m²?g^?1, with an average pore diameter of 1.46?nm.