Ternary Nanoparticles Research Articles

Heusler compounds as ternary intermetallic nanoparticles: Co2FeGa

This work describes the preparation of ternary nanoparticles based on the Heusler compound Co2FeGa. Nanoparticles with sizes of about 20 nm were synthesized by reducing a methanol impregnated mixture of CoCl2 · 6H2O, Fe(NO3)3 · 9H2O and Ga(NO3)3 · xH2O after loading on fumed silica. The dried samples were heated under pure H2 gas at 900 °C. The obtained nanoparticles—embedded in silica—were investigated by means of x-ray diffraction (XRD), transmission electron microscopy, temperature dependent magnetometry and Mößbauer spectroscopy. All methods clearly revealed the Heusler-type L21 structure of the nanoparticles. In particular, anomalous XRD data demonstrate the correct composition in addition to the occurrence of the L21 structure. The magnetic moment of the particles is about 5μB at low temperature in good agreement with the value of bulk material. This suggests that the half-metallic properties are conserved even in particles on the 10 nm scale.

Photovoltaic Devices Employing Ternary PbSxSe1-x Nanocrystals

We report solar cells based on highly confined nanocrystals of the ternary compound PbS(x)Se(1-x). Crystalline, monodisperse alloyed nanocrystals are obtained using a one-pot, hot injection reaction. Rutherford back scattering and energy-filtered transmission electron microscopy suggest that the S and Se anions are uniformly distributed in the alloy nanoparticles. Photovoltaic devices made using ternary nanoparticles are more efficient than either pure PbS or pure PbSe based nanocrystal devices.

Amide-based Room Temperature Molten Salt as Solvent cum Stabilizer for Metallic Nanochains

A simple and efficient method for spontaneous organization of long assemblies of gold nanoparticles is described. This is achieved in a molten solvent containing acetamide, urea and ammonium nitrate that acts as a solvent cum stabilizer. There is no external aggregating agent or stabilizing agent added to the system. Depending on the concentration of the metal salt in the ternary melt, either chain-like assemblies or individual nanoparticles could be obtained. The amine groups present in the components of the melt (acetamide and urea) help in the stabilization of nanoparticles. Ammonium ions present in the eutectic mixture are likely to assist in the organization of the particles. The method is simple, highly reproducible and does not require any templating agent for the formation of chain-like assemblies.

Anionic solid lipid nanoparticles supported on protamine/DNA complexes

The objective of this study was to design novel anionic ternary nanoparticles for gene delivery. Theseternary nanoparticles were equipped with protamine/DNA binary complexes (150–200 nm) as thesupport, and the anionic formation was achieved by absorption of anionic solid lipid nanoparticles(≤20 nm) onto the surface of the binary complexes. The small solid lipid nanoparticles (SLNs)were prepared by a modified film dispersion–ultrasonication method, and adsorption of theanionic SLNs onto the binary complexes was typically carried out in water via electrostaticinteraction. The formulated ternary nanoparticles were found to be relatively uniform in size(257.7 ± 10.6 nm) with a ‘bumpy’ surface, and the surface charge inversion from19.28 ± 1.14 mVto −17.16 ± 1.92 mV could be considered as evidence of the formation of the ternarynanoparticles. The fluorescence intensity measurements from threebatches of the ternary nanoparticles gave a mean adsorption efficiency of96.75 ± 1.13%. Circular dichroism spectra analysis showed that the protamine/DNA complexes had beencoated by small SLNs, and that the anionic ternary nanoparticles formed did not disturbthe construction of the binary complexes. SYBR Green I analysis suggested that theternary nanoparticles could protect the DNA from nuclease degradation, and cell viabilityassay results showed that they exhibit lower cytotoxicity to A549 cells compared with thebinary complexes and lipofectamine. The transfection efficiency of the ternarynanoparticles was better than that of naked DNA and the binary complexes, and almostequal to that of lipofectamine/DNA complexes, as revealed by inversion fluorescencemicroscope observation. These results indicated that the anionic ternary nanoparticlescould facilitate gene transfer in cultured cells, and might alleviate the drawbacksof the conventional cationic vector/DNA complexes for gene delivery in vivo.

A molecular precursor approach for the synthesis of composition-controlled ZnxCd1−xS and ZnxCd1−xSe nanoparticles

Ternary ZnxCd1−xS and ZnxCd1−xSe nanoparticles have been synthesized using a low temperature molecular precursor approach. The co-injection of silylated metal chalcogenolate complexes [(N,N′-TMEDA)Zn(ESiMe3)2] (E = S, 1; E = Se, 2) and [(N,N′-TMEDA)Cd(ESiMe3)2] (E = S, 3; E = Se, 4) to solutions of (N,N′-TMEDA)M(OAc)2 (M = Zn, Cd) in THF resulted in the formation of nanocrystalline quantum dots with particle sizes in the 2–3 nm range. Nanoparticles with Zn mole fractions (x) ranging from 0.95 to 0.05 can be achieved via manipulation of the reaction stoichiometry of 1(2) and 3(4). The size uniformity of the ternary nanoparticles permits control of the absorption properties by changing the metal ion composition. UV-visible and NMR spectroscopy, thermogravimetric analysis as well as X-ray and electron diffraction studies provide substantial evidence that the Zn(II) and Cd(II) ions are homogeneously mixed both within the cores of the nanoparticles and at the particle surfaces. Further control of the optical properties of the ternary materials was achieved via the growth of the particles in hot hexadecylamine while maintaining the Zn/Cd ratio.

Direct Synthesis of Isolated L1<sub>0</sub>-FePtCu Nanoparticles by RF-Magnetron Sputtering

Isolated and oriented hard magnetic FePtCu ternary alloy nanoparticles with the L10-type ordered structure have been directly fabricated by rf-magnetron sputtering onto NaCl substrate kept at 613K without any post-deposition annealing. Structure and morphology of those particles were studied by TEM. When the sputtering duration decreases, the particle size decreases and the particle areal number density increases. These nanoparticles have <100> orientation on the NaCl substrate. Alloy composition distribution from particle to particle examined by nano-beam elemental x-ray analysis was found to be quite small, which can be attributed to the homogeneous structure formed by co-deposition of Fe, Pt and Cu by sputtering. Thermal fluctuation of the magnetization becomes prominent in the specimen with the particle size smaller than about 10nm in diameter.

Deposition of Ru-Ni-S Nanoparticles on Carbon by Spray-Pyrolysis: Effects of Solvent and other Processing Parameters

Nanoparticles of Ru-Ni-S were synthesized in a single-step spray-pyrolysis process as potential catalysts for fuel cells and other applications. The liquid precursors containing ruthenium, nickel, and sulfur were nebulized by an ultra-sonic atomizer to generate aerosol droplets, which were subsequently decomposed to form uniformly distributed nanoparticles for deposition on a carbon thin film. It was observed that the application of methanol as solvent has a strong effect on the particle morphology, size, and composition. The morphology of the Ru-Ni-S nanoparticles changed from spherical with water as solvent, to dendrites upon increase in the methanol con- centration in the precursor solution. It was also found that the pyrolysis temperature strongly affected the particle morphology when methanol was used as solvent. High temperatures promote dendrite formation. When a water/methanol mixture was used as solvent, crys- talline ternary nanoparticles of Ru-Ni-S on a carbon layer were formed at lower temperatures. A very interesting and unique structure of spherical clusters of crystalline particles attached by a chain of crystalline nanoparticles was synthesized. Elemental analysis obtained with EDS attached to the SEM used for particle characterization has confirmed the existence of all elements of interest, and X-ray map- ping showed all elements were distributed uniformly in the nanoparticles. Spray-pyrolysis processing is a versatile technique for produc- tion of inorganic materials of a wide range of composition, size, and morphology. It typically consists of several steps that may include: precursor preparation, precursor atomization, droplet evaporation, droplet precipitation, droplet drying, droplet coagulation, thermoly- sis, and sintering. An review on spray-pyrolysis processing by Messing et al. (1) has discussed the fundamental process parame- ters enabling the formation of particles with controlled morphology and composition. Among the important process parameters in spray-pyrolysis processing, the effects of precursor properties on particle size, composition, and morphology are probably the least understood. Synthesis of electrocatalysts in a spray-pyrolysis process for different types of fuel cells is a relatively new application of the spray-pyrolysis technique. Tolerance to small amounts of carbon monoxide and sulfur is important for proton exchange membrane fuel cells operating on hydrogen obtained by reforming carbon- based fuels. Conventional nanoparticles (2-5 nm) of platinum-based metal alloys are used as both anode and cathode catalysts for proton exchange membrane fuel cells due to the high activity for both hy- drogen oxidation and oxygen reduction (2). However the platinum- based catalysts used today suffer high polarization losses, reducing performance and fuel efficiency due to particle agglomeration, car- bon monoxide and sulfur poisoning (2, 3). The search for carbon monoxide and/or sulfur-tolerant non-platinum electrocatalysts for fuel cell applications have been a very active research endeavor (4- 10). Only a few researchers have studied the platinum- and ruthe- nium-based nanoparticles for methanol oxidation in fuel cell appli- cations. The binary and ternary crystalline nanoparticles were sup- ported on carbon nanofilm as fuel cell catalysts. Waszczuk et al. (11) studied the methanol adsorption on platinum-ruthenium sur- faces and observed that the decomposition of methanol is quite different at ultra-high vacuum. It was observed that the behavior of simple molecules would be different under ultra-high vacuum. Con- trol of size, morphology, and composition of nanoparticles is im- portant in the synthesis processing of ceramic powders. It was

Epoxide assisted sol-gel synthesis of rutile Ni x Ti1-3x Sb2x O2 solid solution nanoparticles

Rutile NixTi1-3xSb2xO2 solid solution nanoparticles were synthesized by a sol-gel route using propylene oxide as a gelation agent. Titanium oxide nanopowder and 12% TiCl3 solution were used as the source for titanium to investigate the influence of the titanium precursors on the formation of the target materials. It was found that the nanoparticles prepared using 12% TiCl3 solution showed a much lower phase formation temperature (700°C) as compared to those prepared from TiO2 nanoparticles (1000°C). This lower phase formation temperature allowed a substantial reduction of the aggregation of the particles during calcination leading to the formation of nearly mono-dispersed nanoparticles of about 20 nm. The results of this work show that the epoxide assisted sol-gel method is capable to produce titanium-based ternary oxide solid solution nanoparticles, owing to the formation of a highly homogeneous precursor gel intermediate.

Microemulsion Synthesized Pt ∕ Ru ∕ Sn Nanoparticles on BDD for Alcohol Electro-oxidation

Ternary Pt-based nanoparticles (nominal composition ) were synthesized via the microemulsion route and deposited onto boron-doped diamond (BDD) electrode. The particle size measured by transmission electron microscopy was in the diam range. X-ray photoelectron spectroscopy revealed a slightly different surface composition from that of the bulk and showed no chemical shift of the line in ternary nanoparticles. For both methanol and ethanol electro-oxidation, the ternary catalyst exhibited lower onset potentials than either pure Pt or the corresponding bimetallic ( and ) catalysts. The ternary catalyst was more efficient for methanol oxidation than for complete oxidation of ethanol, because ethanol electro-oxidation was stopped at acetaldehyde and/or acetic acid formation, the ternary catalyst being unable to activate the C-C bond scission.

Study of Solution Grown Variable BandGap Pb1 − xMnxS Semiconductor Nanoparticle Films

Single-phase nanoparticle films were prepared using an electroless solution growth technique. Face centered cubic structure with a decrease of lattice parameter for an increase of in the alloy films was observed. Composition dependence of optical and electrical properties is discussed. The optical bandgap could be varied from 1.50 to by changing the in the range for the films. Effect of the grain size and the effect of alloying on optical properties are distinguished for the ternary nanoparticle films. Variable range hopping has been identified as mechanism for conduction in the p-type semiconductor nanoparticle films. Mobility (μ of the majority carriers shows a decrease with increase in Mn concentration and follows a temperature dependence, indicating the surface scattering of carriers in the nanoparticle films.

Preparation of Pt-Ru-Ni ternary nanoparticles by microemulsion and electrocatalytic activity for methanol oxidation

Ternary platinum-ruthenium-nickel nanoparticles are prepared by water-in-oil reverse microemulsions of water/Triton X-100/propanol-2/cyclohexane. Nanoparticles formed in the microemulsions are characterized by transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDX). These resulting materials showed a homogenous alloy structure, the mono-dispersion and an average diameter of 2.6 ± 0.3 nm with a narrow particle size distribution. The composition and particle size of ternary Pt-Ru-Ni nanoparticles can be controlled by adjusting the initial metal salt solution and preparation conditions. Pt-Ru-Ni ternary metallic nanoparticles showed an enhanced catalytic activity towards methanol oxidation compared to Pt-Ru bimetallic nanoparticles.

Composition- and Shape-Controlled Synthesis and Optical Properties of ZnxCd1-xS Alloyed Nanocrystals

Composition-tunable ZnxCd1–xS alloyed nanocrystals have been synthesized by a new approach consisting of thermolyzing a mixture of cadmium ethylxanthate (Cd(exan)2) and zinc ethylxanthate (Zn(exan)2) precursors in hot, coordinating solvents at relatively low temperatures (180–210 °C). The composition of the alloyed nanocrystals was accurately adjusted by controlling the molar ratio of Cd(exan)2 to Zn(exan)2 in the mixed reactants. The alloyed ZnxCd1–xS nanocrystals prepared in HDA/TOP (HDA: hexadecylamine; TOP: trioctylphosphine) solution exhibit composition-dependent shape and phase structures as well as composition-dependent optical properties. The shape of the ZnxCd1–xS nanocrystals changed from dot to single-armed rod then to multi-armed rod with a decrease of Zn content in the ternary nanoparticles. The alloying nature of the ZnxCd1–xS nanocrystals was consistently confirmed by the results of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and UV-vis absorption and photoluminescence (PL) spectroscopy. Further, the shape-controlled synthesis of the ternary alloyed nanocrystals was realized by selecting appropriate solvents. Uniform nanodots in the whole composition range were obtained from TOPO/TOP solution, (TOPO: trioctylphosphine oxide) and uniform nanorods in the whole composition range were prepared from HDA/OA solution (OA: octylamine). The effect of the reaction conditions, such as solvent, reaction temperature, and reaction time, on the PL spectra of the alloyed ZnxCd1–xS nanocrystals was also systematically studied, and the reaction conditions were optimized for improving the PL properties of the nanocrystals.

Galactosylated ternary DNA/polyphosphoramidate nanoparticles mediate high gene transfection efficiency in hepatocytes

Galactosylated polyphosphoramidates (Gal-PPAs) with different ligand substitution degrees (6.5%, 12.5% and 21.8%, respectively) were synthesized and evaluated as hepatocyte-targeted gene carriers. The in vitro cytotoxicity of Gal-PPA decreased significantly with an increase in galactose substitution degree. The affinity of Gal-PPA/DNA nanoparticles to galactose-recognizing lectin increased with galactose substitution degree. However, decreased transfection efficiency was observed for these galactosylated PPAs in HepG2 cells. Based on the results of gel retardation and polyanion competition assays, we hypothesized that the reduced transfection efficiency of Gal-PPA/DNA nanoparticles was due to their decreased DNA-binding capacity and decreased particle stability. We therefore prepared nanoparticles by precondensing DNA with PPA at a charge ratio of 0.5, yielding nanoparticles with negative surface charge, followed by coating with Gal-PPA, resulting in a Gal-PPA/ DNA/PPA ternary complex. Such a ternary nanoparticle formulation led to significant size reduction in comparison with binary nanoparticles, particularly at low N/P ratios (2 to 5). In HepG2 cells and primary rat hepatocytes, and at low N/P ratios (2 to 5), transfection efficiency mediated by ternary nanoparticles prepared with 6.5% Gal-PPA was 6–7200 times higher than PPA-DPA/DNA nanoparticles. Transgene expression increased slightly at higher N/P ratios in HepG2 cells and reached a plateau at N/P ratios between 5 and 10 for primary rat hepatocytes. Such an enhancement effect was not observed in HeLa cells that lack of asialoglycoprotein receptor (ASGPR). Nevertheless, transfection efficiency of ternary particles decreased dramatically, presumably due to the decreased DNA binding capacity and particle stability, as PPA galactosylation degree increased. This highlights the importance of optimizing ligand conjugation degree for PPA gene carrier.

Static and in situ TEM investigation of phase relationships, phase dissolution, and interface motion in Ag–Au–Cu alloy nanoparticles

Ternary nanoparticles of Ag–Au–Cu alloy were fabricated by physical vapor deposition of a ternary alloy source onto a heated amorphous carbon film in ultra-high vacuum. The as-cooled nanoparticles were studied using bright-field imaging, selected-area diffraction, energy-dispersive X-ray spectroscopy and high-resolution imaging in the transmission electron microscope (TEM). These analyses revealed the presence of two phases in the 20–50 nm diameter nanoparticles: a Ag-rich fcc α 1 phase and an ordered L1 2 phase (AuCu 3 prototype). The phases were found to have a cube-on-cube (or parallel) orientation relationship with α 1–L1 2 interfaces that were parallel to {1 0 0}. In situ heating of the particles in the TEM showed that the α 1–L1 2 {1 0 0} interface dissolved by steps one moiré-fringe spacing high, consistent with recent theories of interface movement. In contrast to previous studies on the stability of ordered phases in Au–Cu alloys, the ordered L1 2 phase in the Ag–Au–Cu alloy remained at temperatures several hundred degrees higher than predicted from the equilibrium bulk phase diagram. This may be caused by elastic stabilization of the phase due to the small size of the particles and/or composition modulations induced by the surface.

Solution grown Pb 1− xCo xS semiconductor nanoparticle films

Pb 1− x Co x S ternary alloy films were grown using solution growth technique. X-ray fluorescence spectroscopy was used for compositional analysis. X-ray diffraction and atomic force microscopy analysis indicate the presence of nanometer-size grains in the films. Size dependence of optical band gap ( E g) is observed in the ternary nanoparticle films. Increase in E g and decrease in DC-conductivity with increase in Co concentration is also observed.

Optical and magnetic properties induced by structural confinement of ternary chalcogenide in SBA-15 nanotube

The amorphous ternary material, Ni3(SbTe3)2 was prepared using a rapid precipitation reaction between the Zintl phase K3SbTe3 and NiBr2 in solution. This material induced by the incorporation of ternary chalcogenide into long range ordered mesoporous SBA-15 was transformed into ternary nanoparticles. Structural confinement of the amorphous ternary chalcogenide in the mesoporous silica tube causes the suppression of phonon coupling to photoexcited carriers in the confined ternary chalcogenide, resulting in narrower photoluminescence (PL) band than those of the bulk ternary chalcogenide. It also gives rise to ferromagnetic behavior of the nanoparticles made from the material, which is a spin glass with the freezing temperature of 4.0 K in a bulk form. The physical and chemical properties of obtained ternary bulk and nanoparticles have been investigated by x-ray diffraction, superconducting quantum interference device, transmission electron microscopy, Brunauer–Emmett–Teller, and PL (steady-state photoluminescence spectroscopy). The role played by the modified SBA-15 porous silica in controlling ternary chalcogenide size and quantities has been discussed.