Synthesis of mercuric iodide and bismuth tri‐iodide nanoparticles for heavy metal iodide films nucleation

We synthesized mercuric iodide and bismuth tri‐iodide nanoparticles by suspension in octadecene, from Hg(NO₃)₂.H₂O and I₂, and from Bi(NO₃)₃.5H₂O and I₂, respectively. The best synthesis conditions were 2 h at 70‐80 °C, followed by 10 min at 110 °C for mercuric iodide nanoparticles, and 4 h at 80‐110 °C, followed by 10 min at 180‐210 °C for bismuth tri‐iodide ones. Nanoparticles were then washed and centrifuged with ether repeatedly. Compounds identity was confirmed by X‐ray diffraction (XRD) and energy dispersive spectrometry (EDS). We found shifts of the X‐ray diffraction maxima for nanoparticles of both compounds. We characterized the nanoparticles by transmission (TEM) and scanning (SEM) electron microscopy. We obtained disk‐like and squared mercuric iodide nanostructures, 80‐140 nm and 100‐125 nm in size respectively. We also obtained rounded and rod‐like bismuth tri‐iodide nanoparticles, 30‐500 nm in size. Acetonitrile and isopropanol suspensions of mercuric iodide nanoparticles, and acetonitrile suspension of bismuth tri‐iodide nanoparticles exhibited peak maxima shifts in their UV‐Vis spectra. We synthesized for the first time mercuric iodide and bismuth tri‐iodide nanoparticles by the suspension method, although we have not yet obtained uniform shape and size distributions. They offer interesting perspectives for crystalline film nucleation and for improving current applications of these materials, as well as for opening new ones. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

TiO2 nanoparticles synthesis for application in proton exchange membranes

In the present paper, suitable TiO₂ nanoparticles are successfully synthesized by sol‐gel method, in order to utilize the freshly prepared TiO₂ nanoparticles for proton exchange membrane (PEM) preparation. Titanium tetrachloride (TiCl₄) is used as precursor and ethanol as a solvent. The optimum and suitable TiO₂ nanoparticles were obtained by varying gelatinisation time (4–120 h), concentration of precursor (TiCl₄) in ethanol (2–15 vol%), and reaction temperature (15–35 °C). The morphology, size and purity of the nanoparticles are investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and X‐ray diffraction (XRD). Optimum results were found at 4 h of gelatinisation time, 10% precursor concentration and 25 °C temperature for preparation of TiO₂ nanoparticles. Thus prepared nanoparticles are found to be suitable for preparation of nanocomposite PEM, and consequently the prepared PEM indicates enhanced properties, such as, higher thermal stability (high glass transition temperature of 184.1 °C), excellent proton conductivity (0.0822 S cm⁻¹ at room temperature) and low methanol permeability (1.11 × 10⁻⁹ cm2 s⁻¹).     

Studies on fabrication of urchin‐like WO3·H2O hollow spheres and their photocatalytic properties

Urchin‐like tungsten oxide hydrate (WO₃ · H₂O) hollow spheres were successfully synthesized via a self‐sacrifice template method at low temperature. The effects of reaction parameters on the preparation were studied in solution. The growth mechanism was also proposed on the basis of experimental results. In addition, the acid amount and temperature have important effects on size control of the as‐obtained samples. The achieved nanoarchitectures have typical diameters of 4–6 μm with nanoflakes of several nanometers at surface. Crystal structure, morphology, and composition of final nanostructures were characterized by X–ray diffraction (XRD) and scanning electron microscopy (SEM). Degradation experiments of organic contaminant were also performed on samples of hollow spheres and walnut‐like structures under visible‐light illumination. Hollow sphere sample exhibited better photocatalytic capability than walnut‐like sample. Possible mechanism was studied for WO₃ · H₂O assisted photocatalytic degradation of organic contaminant under visible light.     

Green synthesis by diethylene glycol based solution process and characterization of SnS nanoparticles

Uniform near‐spherical SnS nanoparticles were prepared by a hydrazine hydrate‐assisted diethylene glycol solution synthesis based on the reaction of tin dichloride (SnCl₂·2H₂O) with thioacetamide (H₃CCSNH₂). The as‐prepared SnS nanoparticles were characterized by XRD, FETEM, EDS, XPS and UV‐vis‐NIR spectrophotometer. The results showed that the SnS nanoparticles had orthorhombic crystal structure, good stoichiometry and indirect bandgap of ∼1.1 eV. The nanoparticle size could be controlled by changing injection temperature. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solvothermal synthesis and structural characterization of unfilled and Yb‐filled cobalt antimony skutterudite

Unfilled and ytterbium (Yb)‐filled cobalt antimony (CoSb₃) nanoparticles were synthesized via solvothermal route using sodium borohydride (NaBH₄) as a reducing agent. The effect of various amounts of sodium borohydride on the formation of as‐synthesized CoSb₃ nanoparticles with pure phase was investigated. It is found that a sufficient amount of NaBH₄ was required in order to form pure phase CoSb₃. In addition, the effect of annealing time and temperature on the phase transformation of the as‐prepared non‐pure phase CoSb₃ sample was also investigated. It is found that annealing at 500 °C for 5 h would eliminate those non‐CoSb₃ phases and result in pure cubic skutterudite phase CoSb₃. Structural characterization of the as‐prepared unfilled and Yb‐filled nanoparticles was carried out with transmission electron microscopy (TEM) which revealed the formation of highly crystalline cubic phase of skutterudite Yb‐filled CoSb₃. Laser induced breakdown spectroscopy (LIBS) confirmed the presence of ytterbium in the Yb‐filled CoSb₃ samples.     

Hydrothermal synthesis of nano‐crystalline BaMoO4 under mild conditions using simple additive

Large‐scale high‐quality BaMoO₄ nanocrystals have been synthesized in aqueous solutions under mild conditions with citrate as a simple additive. The crystals have bone‐like, spindle‐like and wheatear‐like morphologies assembled from nanoparticles, nanofibers and have been characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. The results showed that experimental parameters had great influences on the shape evolution of products. The adjustment of these parameters such as room temperature stirring time, reaction temperature and reaction time of hydrothermal reaction, can lead to obvious morphology changes of products, and the growth mechanism has been proposed. Room‐temperature photoluminescence indicated that the as‐prepared BaMoO₄ nanocrystals had a strong blue emission peak at 481.5 nm. This facile route could be employed to synthesize more promising nanomaterials with interesting self‐assembly structures. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Facile solvothermal synthesis,growth mechanism and thermoelectric property of flower‐like Bi2Te3

Hierarchical flower‐like Bi₂Te₃ was synthesized through a facile solvothermal method. The crystal structure and morphology of the as‐prepared samples were characterized by X‐ray diffraction (XRD), filed emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high resolution TEM. The reaction parameters such as reaction time, the amount of glucose, concentration of NaOH and the reaction temperature were systematically investigated. Based on the FESEM observations, a possible mechanism defined as a self‐assembly process accompanied by anisotropic growth mechanism was proposed. Moreover, the thermoelectric properties were measured at the temperature range of 300–600 K. The hierarchical flower‐like Bi₂Te₃ presented good thermoelectrical properties. The maximum ZT value reached up to 0.6 at 600 K, which was higher than that of Bi₂Te₃ nanoparticles.     

Stability of ruthenium nanoparticles synthesized by solvothermal method

One of the major obstacles to the synthesis of nanoparticles and nanocatalyst is the stability of particles. In the present study, polymer stabilized ruthenium nanoparticles were synthesized by solvothermal method using solutions of ruthenium chloride in ethylene glycol in presence of poly(N ‐vinyl‐2‐pyrrolidone) (PVP) as a stabilizing agent. Stability of nanoparticles was studied by varying different parameters e.g. PVP/RuCl₃ molar raio, RuCl₃ concentration, reaction temperature and time and expressed in terms of particle size and size distribution. Transmission electron microscope (TEM) analysis revealed the presence of metallic clusters with a uniform size of about 20‐65 nm. Dispersion destabilisation of colloidal nanoparticles was detected by Turbiscan. Polymer stabilized ruthenium nanoparticles were dispersed on γ‐alumina to prepare uniformly disperse Ru/γ‐Al₂O₃ catalyst by mechanical strirring and sonication. Inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), X‐Ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Thermo gravimetric analysis (TGA) were used to characterize the supported catalyst. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,Structure and Characterizations of a Molybdenum Sulfide Complex with inorganic Cluster [Mo3S13]2‐ and Organic Amine Me4N+

The complex of (Me₄N)₂Mo₃S₁₃ ( I ) has been synthesized under mild hydrothermal condition. The crystal structure was determined by single crystal X‐ray diffraction at room temperature. Crystal data: M = 854.91, Trigonal, space group P3 (No. 143), a = 11.2351(8) Å, c = 5.8885(6) Å, and Z = 1, There is an inorganic [Mo₃S₁₃]^2‐ core composed of a Mo₃‐triangle, a μ₃‐S atom, three doubly bridging disulfide and three terminal disulfide. Two organic amine ions act as the positive charge to balance the [Mo₃S₁₃]^2‐ cluster.     

Preparation of monodispersed aragonite microspheres via a carbonation crystallization pathway

Monodispersed calcium carbonate microspheres were prepared by carbonating a calcium acetate aqueous solution with CO₂ gas at a high pressure of 40 bar and a high temperature of 80 °C after 60 minutes of reaction. The products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD pattern showed that the crystal polymorph of the as‐prepared monodispersed microspheres was aragonite. The SEM images also displayed needle‐like aragonite self‐organized into microsphere superstructure with diameters ranging from 5 to 15 μm. Analysis of the formation mechanism of the calcium carbonate microsphere superstructure revealed that the rod‐dumbbell‐sphere morphogenesis mechanism along with the phase transformation of vaterite to aragonite was responsible for the growth of the monodispersed aragonite microspheres. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Morphological lattice complexes

Binary and pseudobinary compounds AB like NaCl and CaCO₃, with the center of charge at carbon position, are characterized by self‐coordination numbers of nearest, second and third neighbors T ₁ T ₂ T ₃ of A and B positions. The maximum Madelung factor of compounds with identical T _i values of A and B atoms is obtained for a maximum of B positions at the border of the A–A Dirichlet domain. The A and B positions form a packing with different T _i values, if all B positions are on the border of the Dirichlet domain. This packing like the primitive cubic packing of Na and Cl atoms with T _i values 6 12 8 or the rhombohedrally distorted packing 6 8 6 of CaCO₃ as morphological lattice complexes can be related to cubic NaCl crystals or the cleaved rhombohedron of calcite. A different habit of crystals is expected for sphere, rod or layered packings. Many well‐defined nanoparticles can be obtained from microemulsions at variation of temperature, water content or water partial pressure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Precipitation of nesquehonite from homogeneous supersaturated solutions

The homogeneous (unseeded) precipitation of nesquehonite (MgCO₃·3H₂O) was studied over the temperature range of 10‐40 °C. Precipitation was triggered by the supersaturation created by mixing MgCl₂ solution (0.5‐1.5 M) with Na₂CO₃ solution in the same concentration range. The Meissner's method was adopted in the calculation of supersaturations during the MgCl₂‐Na₂CO₃ reaction to monitor the precipitation. Solids were identified using X‐ray diffraction (XRD) analysis and scanning electron microscope (SEM) images. In the temperature range of 10‐40 °C, MgCO₃·3H₂O with needle‐like or gel‐like morphology was precipitated. It was seen that the length, width and surface smoothness of the particles changed with reaction temperature and supersaturation. The supersaturation (S) was in the range of 1.09‐58.68 during titration of Na₂CO₃ solution. The dimension of the crystals increased with longer addition time (or lower initial concentration of reactant) at the same temperature. Slower addition via titration of 2 h followed by 2 h of equilibration at 40 °C proved successful in producing well developed needle‐like MgCO₃·3H₂O crystals of 30‐50 μm long and 3‐6 μm wide. MgCO₃·3H₂O obtained were calcined to produce highly pure magnesium oxide (MgO) at 800 °C. The morphology of MgO was similar to that of their corresponding precursors. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth of spindle‐shaped silver nanoparticles in SDS solutions

Spindle‐shaped silver nanoparticles were successfully prepared in high yield by a simple wet chemical approach using citric acid (CA) as reducant in the presence of sodium dodecyl sulfate (SDS) at room temperature. Transmission electron microscopy (TEM), UV‐vis absorption spectroscopy and X‐ray diffraction (XRD) have been used to characterize the obtained products. It is found that the spindle‐shaped architecture of siver nanoparticles is drastically influenced by the mass ratio of SDS to CA and the concentration of silver nitrate (AgNO₃). It is revealed that SDS is not as a template but as a capping agent. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural and mechanical properties of KН2PО4 single crystals with embedded nanoparticles and organic molecules

Single crystals of KDP crystals with embedded Urea molecules and TiO₂ nanoparticles have been grown from aqueous solution by the temperature lowering method. The effect of the organic molecules and nanoparticles on the structural and mechanical properties has been studied. It has been observed that addition of Urea molecules improves laser induced damage threshold and mechanical strength of the crystal, while TiO₂ nanoparticles have the opposite effect. The structure and composition of KDP:Urea crystal are studied by three‐crystal X‐ray diffraction analysis, which reveals the existence of a correlation between the increase of the microhardness value and the change of the crystal lattice parameter. The surface features of KDP:TiO₂ crystals are analyzed by scanning electron microscopy that reveals the presence of quasi‐equidistant growth bands caused by capture of the nanoparticles. It is shown that the rise of TiO₂ nanoparticles concentration up to 10⁻⁴ wt.% and higher resulted in 3‐fold reduction of the laser damage threshold of KDP:TiO₂ relative to pure KDP in [001] and [100] crystallographic directions. It is found that microhardness and fracture toughness decrease at the nanoparticles concentration of 10⁻³ wt.% due to crack formation at crystal lattice discontinuities. The grown crystals also have been subjected to dielectric studies.     

Structure of several historic blades at nanoscale

Comparison of the structure of ancient Damascene steel blades at nanoscale with more recent ones – all made using crucible (wootz) technology and exhibiting ultra‐high carbon content – showed for the first time a common feature. Despite different microstructures, colonies of wire‐ and tube‐like particles with diameters of 40‐50 nm have been observed with the aid of high‐resolution transmission electron microscopy. Crystalline Fe₃C is the main phase forming those particles covered in numerous cases by a tube‐like layer. These tubes were also found in an empty or partly – covered filled variant. To assess the strengthening capacity of cementite various models were compared. Dispersion strengthening seems the most efficient. Cutting edge qualities may be related to surface corrugations due to nanoparticles. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and properties of oxide ion conductor Pr2Mo2O9 with La2Mo2O9 structure

Polycrystalline Pr₂Mo₂O₉ samples have been prepared by solid-state synthesis and single crystals of this compound have been grown. Pr₂Mo₂O₉ is unstable in the temperature range 700–900°C and partially decomposes with the formation of Pr₂Mo₃O₁₂ at these temperatures, but upon further heating to 1000–1050°C, Pr₂Mo₂O₉ is recovered. At room temperature, the structure, polymorphism, and physical properties of Pr₂Mo₂O₉ are similar to those of the known oxide ion conductor La₂Mo₂O₉. Pr₂Mo₂O₉ exhibits a reversible first-order phase transition to the cubic phase in the temperature range 520–540°C. The electric conductivity of Pr₂Mo₂O₉ is close to that of La₂Mo₂O₉ and amounts to 3.5 × 10⁻² S/cm at 700°C. The conductivity of Pr₂Mo₂O₉ is described by the Arrhenius law in the low-temperature phase and by the Vogel-Fulcher-Tammann equation in the high-temperature phase.     

Preparation and optical properties of AgGaS2 nanofilms

In this paper, AgGaS₂ nanofilms have been prepared by a two‐step process involving the successive ionic layer absorption and reaction (SILAR) and annealing method. Using AgNO₃, GaCl₃ and Na₂S₂O₃ as reaction sources, the mixture films were firstly deposited on quartz glass substrates at room temperature, and then annealed in Ar environment at 200–500 °C for 4 h, respectively. The effects of annealing temperature on structural and optical properties were investigated by XRD, UV‐Vis, EDS and photoluminescence (PL) spectra. It was revealed in XRD results that α‐Ag₉GaS₆ was contained in the samples annealed at 200 °C, and this phase was decreased with increase of the annealing temperatures. When the sample was annealed at above 400 °C, the chalcopyrite AgGaS₂ nanofilm was obtained. The preferred orientation was exhibited along the (112) plane. It was shown in atomic force microscopy (AFM) results that the grain sizes in AgGaS₂ nanofilms were 18‐24 nm and the thin films were smooth and strongly adherent to the substrates. When the annealing temperature was higher than 400 °C, it is an optimum condition to improve the structural and optical properties of the AgGaS₂ thin films. The room temperature PL spectra of AgGaS₂ nanofilms showed prominent band edge emission at 2.72 eV. Based on all results mentioned above, it can be concluded that the SILAR‐annealing method is preferable to preparing high‐quality AgGaS₂ nanofilms. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A simple glucose reduction route for the synthesis of sheet‐like copper dendrites

In the current paper we designed a simple glucose reduction route for synthesis of sheet‐like Cu dendrites on a high yield, using CuSO₄ as the starting material. The reaction was carried out at 180 °C for 18 h in the absence of any structure‐directing agent. The product was characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and electron diffraction (ED). Some factors influencing the shapes of Cu microcrystals, including the reaction temperature, time, and the concentration of the starting CuSO₄, were investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Flux growth of straw‐like rutile monocrystals

Millimetric straw‐like rutile monocrystals were grown by the flux growth technique. A suitable mixture of flux (MoO₃, V₂O₅, Li₂CO₃) and amorphous TiO₂ gel was slowly cooled down to 750°C from 1250°C or 1350°C. The best yields of straw‐like rutile were obtained with a nutrient/flux ratio and a cooling rate in the range 0.015‐0.006 and 1.8‐1.9 K h^‐1, respectively. The hollowed crystals were characterized by powder and single‐crystal X‐ray diffraction, scanning electron microscopy, microthermometry, and µ‐Raman spectroscopy. As for skeletal crystal, the formation of axial canals in rutile is attributed to a lack of nutrient due to the viscosity of the melt and the high growth rate along [001]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and growth mechanism of ZnO rod‐like nanostructures by a microwave‐assisted low‐temperature aqueous solution route

A zinc oxide (ZnO) nanoarray (rod‐like nanostructure) was successfully synthesized through a low‐temperature aqueous solution and microwave‐assisted synthesis using zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and hexamethylenetetramine (HMTA) as raw materials, and using FTO glass as substrate. The effects of parameters in the preparation process, such as solution concentration, reaction temperature and microwave power, on the morphology and microstructure of ZnO nanoarray were studied. Phase structure and morphology of the products were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that hexagonal wurtzite structure ZnO nanoarray with good crystallization could be prepared through a low‐temperature solution method. When the concentration of the mixed solution was 0.05 M, the reaction temperature was 95 °C, and the reaction time was 4 h, high‐density ZnO regular nanorods of 200 nm diameter were obtained. A possible mechanism with different synthesis methods and the influence of microwave processing are also proposed in this paper.