Synthesis and optical properties of tetragonal KTa0.6Nb0.4O3 nanoparticles

Tetragonal phase KTa_0.6Nb_0.4O₃ (KTN) nanoparticles have been prepared by hydrothermal method. The obtained particles were characterized by X-ray powder diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy and UV-vis absorption spectrum techniques. A systematic change in crystal structure from cubic to tetragonal is observed with the increase of reaction temperature and KOH concentration. Room temperature UV-vis absorption spectrums of KTN particles show that the band gap changes from 3.24 to 3.34 eV with grain size diminished, which reveals the existence of blue-shift phenomenon of absorption bands.     

Preparation and characterization of polymer-supported nano-amorphous Ni–B particles

Polymer-supported nano-amorphous Ni–B particles have been prepared by an ion exchange/chemical reduction protocol. The products were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The polymer-supported Ni–B particles prepared at low temperature are 60–70 nm in size with a Ni–B ratio of Ni₁₉B₁₀.The choice of temperature is a crucial factor affecting particle size.     

Microstructural properties and local atomic structures of cobalt oxide nanoparticles synthesised by mechanical ball-milling process

In this study, facile preparation of pure and nano-sized cobalt oxides particles was achieved using low-cost mechanical ball-milling synthesis route. Microstructural and morphological properties of synthesised products were characterised by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. XRD results indicated that the fabricated samples composed of cubic pure phase CoO and Co₃O₄ nanocrystalline particles with an average crystallite size of 37.2 and 31.8 nm, respectively. TEM images showed that the resulting samples consisted of agglomerates of particles with average diameter of about 37.6 nm for CoO and 31.9 nm for Co₃O₄. Phase purity of the prepared samples was further investigated due to their promising technological applications. Local atomic structure properties of the prepared nanoparticles were probed using synchrotron radiation-based X-ray absorption spectroscopy (XAS) including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). EXAFS data analysis further confirmed the formation of single-phase CoO and Co₃O₄ nanoparticles. In addition, structural properties of cobalt oxide nanoparticles were investigated by performing density functional theory calculations at B3LYP/TZVP level and Born–Oppenheimer molecular dynamics. Theoretical calculations for both prepared samples were found to be consistent with the experimental results derived from EXAFS analysis. Obtained results herein reveals that highly crystalline and pure phase CoO and Co₃O₄ nanoparticles can be synthesised using simple, inexpensive and eco-friendly ball-milling method for renewable energy applications involving fuel cells and water splitting devices.     

Properties of Ferrofluid Nanoparticles Prepared by Coprecipitation and Acid Treatment

A new stable acid water-based CoFe₂O₄ ferrofluid is prepared by coprecipitation and acid treatment. The properties of the nanoparticles forming the ferrofluid are examined by means of X-ray diffraction, vibrating sample magnetometer, scanning tunneling microscopy, transmission electron microscopy and annihilation technique. The results show that the particles are cubic CoFe₂O₄ nanoparticles, which have an average diameter of 12.2nm and are coated with a low density porous amorphous layer. The CoFe₂O₄ particles in an acid aqueous medium exist in two kinds of forms, one is a single spherical particle and another is an aggregation of several spherical particles.     

Changes of structure and composition of a zinc ion-implanted silicon surface during nanoparticle formation upon thermal treatment

Data from investigating the formation of nanoparticles (NPs) on a surface of silicon wafers after zinc ion implantation and thermal annealing are presented. The investigation is conducted by means of trans-mission electron microscopy, electron diffraction analysis, energy dispersive microanalysis, scanning tunneling microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. It is found that on their surfaces, the implanted samples have only films of amorphous silicon containing implanted zinc, oxygen, and carbon contamination. Thermal treatment in the range of 400–800°C leads to the formation NP with 20–50 nm wide and 10 nm tall on a wafer’s surface, plus a silicon oxide layer about 20 nm thick. NPs are composed of zinc compounds of the ZnO, ZnSiO₃, or Zn₂SiO₄ types. These NPs disappear after annealing at 1000°C.     

Characterization of Fe and Fe50Ni50 ultrafine nanoparticles synthesized by inert gas-condensation method

Nanoparticles of Fe and Fe₅₀Ni₅₀ were synthesized by inert gas-condensation method under pure helium atmosphere. The prepared nanoparticles samples were examined by high-resolution transmission electron microscopy, X-ray diffraction and Mössbauer spectroscopy. The synthesized nanoparticles consisted of core-shell type structure nearly spherical shape with a size comprised within the range 4-70 nm and they occur as clusters or chains. The Mössbauer measurements as well as X-ray diffraction showed, in both cases, the presence of iron-oxide phases.     

A Mössbauer spectroscopy study of chemically prepared ultrafine particles of amorphous (Fe1-xCox)60B40

Ultrafine amorphous alloy particles of (Fe_1-x Co_x)₆₀B₄₀ with x=0.1, 0.3, 0.5, 0.7, and 0.9 have been prepared by reduction of the metal ions using KBH₄ in aqueous solution. electron microscopy shows that the particle size is of the order of 20 nm. Mössbauer spectroscopy has been used to elucidate the magnetic properties of the particles.     

毛刺状竹节结构氮化硼纳米管的合成与生长机理

以非晶硼和氧化镍纳米颗粒为原料,在氨气中1100 oC下合成了毛刺状竹节结构的氮化硼纳米管. 利用X射线衍射和透射电镜研究了氮化硼纳米管的结构和形貌. 竹节结构纳米管表面的毛刺是六方氮化硼的纳米薄片. 提出了一种基于固态硼和气态二氧化硼扩散的毛刺形貌生长机理.     

Low temperature thermoelectric properties of Cu intercalated TiSe2: a charge density wave material

Y₂O₃ nanoparticles and nanorods have been firstly synthesized in bulk Ti-Y films prepared by magnetron sputtering on Si (100) substrates at different temperatures. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS) are used to characterize the structure, morphology, and composition of the as-synthesized nanoparticles and nanorods. The mechanical properties of the sputtered films are investigated using nanoindentation techniques. The results indicate that both the nanoparticles and nanorods have a pure cubic Y₂O₃ structure resulting from the reaction of Y atoms with the residual O₂ in the vacuum chamber, and are free from defects and dislocations with uniform diameters of about 30 nm. The Y₂O₃ nanoparticles mainly distribute at the grain boundaries of the Ti matrix and the nanorods have lengths ranging from 250 nm to more than 1 μm with the growth direction parallel to the (002) plane. As the growth temperature elevates, the nanoparticles turn to be coarsening while more and longer nanorods are inclined to form. Compared with the Ti film, the TiY films have a remarkable increase in hardness, but do not exhibit expected increase in elastic modulus. Finally, the growth mechanism is also briefly discussed.     

Green synthesis of soya bean sprouts-mediated superparamagnetic Fe3O4 nanoparticles

Superparamagnetic Fe₃O₄ nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe₃O₄ nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe₃O₄ nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe₃O₄ nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature (T_B) of 150 K and saturation magnetization of 37.1 emu/g.     

Synthesis of ZnFe2O4 nanocrystallites by mechanochemical reaction

Mechanochemical reaction of ZnO and α-Fe₂O₃ in a planetary mill formed an amorphous precursor, which was subsequently heated to successfully produce zinc ferrite (ZnFe₂O₄) nanocrystallites. The amorphous precursor and nanocrystallites were characterized by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Calcination of the precursor powder at 600 °C led to the formation of ZnFe₂O₄ nanocrystallites of about 22 nm in crystal size, and most of particle was about 10-50 nm in diameter. Effect of calcination temperature on the crystal size of the nanoparticles was investigated. The mechanism of nanocrystallite growth was primarily investigated. The activation energy of ZnFe₂O₄ nanocrystallite formation during thermal treatment was calculated to be 18.5 kJ/mol.     

Synthesis,characterization, and electrochemical properties of lithium-based fluorosulfate nanoparticles as cathode for lithium-ion batteries

Lithium-based fluorosulfate nanoparticles were synthesized by a simple and fast solid state reaction from the precursors FeSO₄?7H₂O and LiF ground by high energy ball milling. Through the introduction of excess of LiF, relatively pure LiFeSO₄F phase with polycrystalline structure was obtained. The structure, morphology, and element valence state were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). The results demonstrate uniformly distributed particles and larger particles consisted of single crystalline structure, besides the valence states for different elements were analyzed and Fe²⁺ was confirmed. The cyclic voltammograms (CV) and charge-discharge cycling performances were employed to characterize electrochemical properties of prepared cathode material. It is very interesting that double redox peaks appeared reversibly. Meanwhile, it exhibited a relatively higher first-discharge capacity of 115 mAh/g at 0.05C and it still maintained above 60 mAh/g capacity after experiencing 30 times cycles at final 2C rate.     

Surface characterization and catalytic CO + H2 reaction on Fe82.2B17.8 amorphous alloy

Fe_82.2B_17.8 amorphous ribbon has been used as a catalyst for the Fischer-Tropsch-type reaction of CO+H₂. Specific activity has been found to be at least an order of magnitude higher than that of either the crystallized ribbon of identical composition or the supported iron catalyst. Before and after the catalytic tests the ribbons were characterized by XRD, XPS, UPS and Mössbauer spectroscopy in transmission and in conversion electron modes. Conversion electron Mössbauer spectroscopy and UPS proved that the surface of the amorphous ribbons is being partially crystallized during 8000 min reaction time at a maximum reaction temperature of 560 K. The superior catalytic activity has been explained by stabilization of the small iron particles and Fe₂O₃ by boron atoms at the surface and by suppressed carbide formation.     

siRNA-loaded PEGylated porous silicon nanoparticles for lung cancer therapy

The BiPO₄/reduced graphene oxide (RGO) nanocomposites were prepared by a facile solvothermal approach. The prepared samples were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, electrochemical impedance spectra, and Mott–Schottky and the photoluminescence spectra. A large quantity of BiPO₄ nanoparticles with sizes of ca. 150 nm were well dispersed on the RGO nanosheets. The absorbance of the BiPO₄/RGO nanocomposites is largely enhanced in the range of 400–800 nm compared with that of BiPO₄, and the BiPO₄/RGO showed better photocatalytic activities under simulated sunlight irradiation than the BiPO₄ nanocrystals.     

Large-scale synthesis of single-phase,high-quality GaN nanocrystallites

Large-scale synthesis of high-quality GaN nano-crystallites has been achieved by direct reaction of a 4:1 molar Ga/Ga₂O₃ mixture with ammonia at 950 °C. X-ray diffraction, transmission electron microscopy, selected-area electron diffraction and high-resolution transmission electron microscopy revealed that the produced GaN nanocrystallites were single hexagonal wurtzite structure with an average particle size around 45 nm. A sharp near band edge emission peak and a blue light emission peak were observed in photoluminescence spectroscopy. The synthesis approach is simple and easy to be commercialized. PACS 61.46.+w; 81.15.Gh; 81.05.Ea     

Copper oxide particles produced by laser ablation in water

Laser ablation of copper metal in water was performed in order to obtain copper oxide particles. Scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, transmission electron microscopy, and electron diffraction were conducted in order to determine the size, shape and structure of the particles. The source of the O atoms in the copper oxide particles is the surrounding water molecules. The copper oxide particles obtained by laser ablation were both crystalline and amorphous. The crystalline particles were determined to be paramelaconite Cu₄O₃.     

Growth of Co nanoparticles on a nanostructured θ-Al2O3 film on CoAl(1 0 0)

We have investigated the growth of Co nanoparticles on θ-Al₂O₃/CoAl(1 0 0) by means of Auger electron spectroscopy (AES), high-resolution electron energy loss spectroscopy (EELS), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Due to Volmer-Weber growth, Co forms particles with a mean diameter of approximately 2.5 nm and height of 0.8 nm. Even on the entirely covered oxide, there is no Ostwald ripening and Co particles stay structurally isolated. The nanoparticles exhibit a small size distribution and tend to form chains, as predetermined by the streak structure of the oxide template. For sufficient high coverages Co-core-CoO-shell nanoparticles may be evidenced, which is explained as a result of surfactant oxygen. The nanostructured particles may open the door to numerous applications, such as in catalysis and magnetoelectronic applications, where large areas of ordered nanodots are desired.     

One-pot production of copper ferrite nanoparticles using a chemical method

Copper ferrite nanoparticles were synthesized via the oxidation of precipitates obtained from the reaction of FeCl₂, CuSO₄ and N₂H₄ in the presence of gelatin. These copper ferrite particles were subsequently examined using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and Mössbauer spectroscopy. The average size of the copper ferrite nanoparticles was less than 5 nm, and they exhibited superparamagnetic behavior as a result of their small size. The low temperature Mössbauer spectrum exhibited three sets of sextets, two corresponding to the tetrahedral and octahedral sites of the copper spinel structure and one with small hyperfine magnetic field corresponding to the surface or defects of the nanoparticles. When the ratio of copper salt was increased, the tetrahedral site became preferable for copper, and metallic copper and copper ferrite were both present in a single nanoparticle.     

Structural, optical and electrical characterization of antimony-substituted tin oxide nanoparticles

Antimony-doped tin oxide (ATO) nanostructures were prepared using chemical precipitation technique starting from SnCl₂, SbCl₃ as precursor compounds. The antimony composition was varied from 5 to 20 wt%. The lower resistance was observed at composition of Sn:95 and Sb:05, when compared with undoped and higher doping concentration of antimony. The average crystalline size of undoped and doped tin oxide was calculated from the X-ray diffraction (XRD) pattern and found to be in the range of 30-11 nm and it was further confirmed from the transmission electron microscopy (TEM) studies. The scanning electron microscopy (SEM) analysis showed that the nanoparticles agglomerates forming spherical-shaped particles of few hundreds nanometers. The samples were further analyzed by energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and electrical resistance measurements.     

Ultra fine carbon nitride nanocrystals synthesized by laser ablation in liquid solution

Crystalline carbon nitride nanopowders and nanorods have been successfully synthesized at room temperature and pressure using the novel technique of pulsed laser ablation of a graphite target in liquid ammonia solution. High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Fourier transform infrared spectroscopy (FTIR) were used to systematically study the morphology, nanostructure and chemical bonding. The experimental composition and structure of the nanoparticles are consistent with the theoretical calculations for α-C₃N₄. After 2 h ablation the particles had a size distribution ∼8–12 nm, whereas after 5 h ablation the particles had grown into nanorod-like structures with a crystalline C₃N₄ tip. A formation mechanism for these nanorods is proposed whereby nanoparticles are first synthesized via rapid formation of an embryonic particle, followed by a slow growth, eventually leading to a one-dimensional nanorod structure.