Novel method for the preparation of core-shell nanoparticles with movable Ag core and polystyrene loop shell

Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag@PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: γ-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under γ-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe²⁺-EDTA-SFS) as the redox initiation pair. The resulted Ag@PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).     

Synthesis on an ultra large scale of nearly monodispersed γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles with La(III) doping through a sol–gel route assisted by propylene oxide

Nearly monodispersed La³⁺ doped γ-Fe₂O₃ nanoparticles were synthesized on an ultra-large scale of about 60 g in a single reaction by a low temperature sol–gel route. The nanoparticles were obtained by the reaction of FeCl₂ and La(NO₃)₃ in ethanol solution with propylene oxide to form the sol, followed by the boiling of the sol solution. The La³⁺ doping promotes the phase transformation temperature of γ-Fe₂O₃ nanoparticles from 350 to 650 °C by the La³⁺ doping induced enhancement of phase transformation activation energy. This large scale synthesis strategy offers important advantages over other conventional routes for the preparation of undoped and doped γ-Fe₂O₃ nanoparticles. These guarantee the promising application of this route in the industrial production.     

Sol-Gel Processing of Sm2+-Doped Glass and Its Spectral Hole Burning at Room Temperature

The sol-gel process was applied to the preparation of Sm²⁺ ion-doped silicate glasses, which show persistent spectral hole burning at room temperature. The gels synthesized by the hydrolysis of metal alkoxides and SmCl₃·6H₂O were heated in air at 500°C, were then reacted with H₂ gas to form the Sm²⁺ ion. The Al₂O₃−SiO₂2 glasses are appropriate to reduce the Sm³⁺ ion with H₂ gas and show intense photoluminescence of Sm²⁺ ion. Persistent spectra hole burning was observed in the excitation spectrum for the⁷F₀→⁵D₀ transition of the Sm²⁺ ion by the irradiation of DCM dye laser. The hole width and depth were ∼16 cm⁻¹ and ∼10% of the total intensity, respectively, at 20°C.     

Sorption of radiocobalt on a novel γ-MnO2 hollow structure: effects of pH, ionic strength, humic substances and temperature

A novel γ-MnO₂ hollow structure has been synthesized using a simple chemical reaction between MnSO₄ and KMnO₄ in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. As an example of potential applications, γ-MnO₂ hollow structure was used as adsorbent in radionuclide ⁶⁰Co(II) treatment, and showed an excellent ability. The effect of pH, contact time, ionic strength, humic acid (HA)/fulvic acid (FA), and temperature was investigated using batch techniques. The results indicated that the sorption of ⁶⁰Co(II) on γ-MnO₂ was obviously dependent on pH values but independent of ionic strength. The presence of HA/FA enhanced the sorption of ⁶⁰Co(II) on γ-MnO₂ at low pH, whereas reduced ⁶⁰Co(II) sorption on γ-MnO₂ at high pH. The kinetic sorption of ⁶⁰Co(II) on γ-MnO₂ can be well fitted by the pseudo-second-order rate equation. The thermodynamic parameters (ΔH ⁰, ΔS ⁰, ΔG ⁰) were also calculated from the temperature dependent sorption isotherms, and the results suggested that the sorption of ⁶⁰Co(II) on γ-MnO₂ was a spontaneous and endothermic process. The sorption of ⁶⁰Co(II) on γ-MnO₂ was attributed to surface complexation rather than ion exchange.     

Synthesis and study of the properties of K2Y1 ? x ? yEuxTby(MoO4)(PO4) and K2Y1 ? x ? yEuxTby(MoO4)(PO4)1?δ(VO4)δ solid solutions

Al synthesized samples are isostructural and crystallize in the orthorhombic symmetry system, space group Ibca. Particles of the final product of ∼200 nm in size have been obtained. The introduction of the vanadate anion into the matrix composition leads to the lowering of the symmetry of the Eu³⁺ environment and to the rise of the defect luminescence at 450–550 nm because of the unit cell distortion. The luminescence of defects in terbium-europium-containing samples is determined by the sample surface area, which decreases on annealing. The τ, W ₀ and γ parameters of the luminescence kinetics of the samples have been determined.     

Influence of γ-irradiation on the kinetics of heat release during the interaction of an aqueous solution of HNO3 with aliphatic hydrocarbons

The influence of preliminary γ-irradiation and γ-irradiation during hte oxidation process on the kinetics of heat release in the systemsn-decane—aqueous solution of HNO₃ and a solution of tributyl phosphate in a kerosene—aqueous solution of HNO₃ was studied. The preliminary γ-irradiation of the system at 43°C increases the initial rate of the process (k ₁). The increase is proportional to the irradiation dose at doses up to 150kGy, then the increase ink ₁ is retarded, and the further course of the process becomes practically independent of the irradiation dose. The effect of γ-irradiation during the oxidation depends on the temperature of the system: at temperatures lower than 80 °C, γ-irradiation increases the rate of heat release, whereas at higher temperatures, γ-irradiation decreases the rate of heat release. The effects observed were explained by the competition of NO₂ accumulation due to the radiolysis of nitric acid and processes of the addition of NO₂ to unsaturated hydrocarbons produced by the radiolysis of the organic phase. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1116–1120, June, 1998.     

Uptake of some lanthanides on γ-zirconium phosphate-phosphite and its 1,10-phenanthroline and 2,2-bipyridyl intercalated products

γ-Zirconium phosphate-phosphite, γ-Zr·PO₄·H₂PO₃·2H₂O, (γ-ZrPP), was prepared and characterized. Direct treatment of γ-zirconium phosphate-phosphite with an ethanol solution of 0.1M 1,10-phenanthrolin and 2,2'-bipyridyl gave the well defined composites, γ-Zr·PO₄·H₂PO₃(phen)_0.15·H₂O and γ-Zr·PO₄·H₂PO₃(bipy)_0.18·0.6H₂O respectively.K _d values of a mixture of lanthanide ions: La³⁺, Sm³⁺, Eu³⁺ and Yb³⁺ for the intercalated products and for γ-ZrPP in HNO₃ solution at room temperature and at pH 2 and 4 were determined by a radiotracer technique.¹⁴⁰La,^152mEu,¹⁵³Sm and¹⁷⁵Yb radioisotopes were used for the equilibration experiment using 500 μl (4.0·10⁻⁵ mmole) each of the solutions of the tracers as a mixture in 7.5 M HNO₃ solution at the desired pH with 0.1 g of γ-ZrPP and of the intercalated products. The selectivity order was found to be dependent on the nature of the ligand and on the pH. The 2,2'-bipyridyl product posseses, at pH 2 in general, a highK _d value, specially for Sm³⁺ (9815.9) compared to that of the 1,10-phenanthrolin product (3375.5) and to γ-ZrPP (419.8). This could be attributed to partial deintercalation of the 2,2'-bipyridyl at pH 2 and increasing of ionogenic groups.     

Fabrication of size-controllable and luminescent dysprosium benzenetricarboxylate nanobelts at room temperature

Lanthanide-based coordination polymer Dy(1,3,5-BTC)(H₂O)₆ nanobelts were successfully synthesized on a large scale through an extremely simple approach at room temperature; the size of the nanobelts can be easily tuned from several to several hundred micrometers in length, 70–600 nm in width, and 10–100 nm in thickness by varying concentrations, solvent, and surfactant reasonably. In addition, the as-obtained dysprosium benzenetricarboxylate nanobelts exhibit the characteristic emission of the Dy³⁺ ions, making the belt-like coordination polymer have potential applications in building minioptoelectronic devices.     

Radiation-chemical reduction of CO2+ ions in aqueous solution. Metal sols and their properties

The radiation-chemical reduction of Co²⁺ ions in an aqueous solution of Co(ClO₄)₂ containing sodium formate was studied. Stable metal sols containing spherical particles with a diameter of 2–4 nm are formed under γ-irradiation in the presence of polyacrylate as the stabilizing additive. An aqueous solution of colloidal cobalt has an optical absorption that increrases smoothly in the UV region without a maximum to 200 nm (ɛ₂₀₀=1.3·10⁴ mol^-1 L cm^-1). It is established that the radiation-chemical reduction of the Co²⁺ ions occursvia an autocatalytic mechanism. The metal sols catalyze the reduction of the Co²⁺ ions by Co₂ ⁻ radical ions formed under irradiation. The properties of the sols were studied, and it is shown that they are readily oxidized by hydrogen peroxide and other oxidants. The mechanism of chemical reactions involving the sols is discussed. Tranalated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1959–1964, October, 1998.     

Effect of Al doping on the conductivity type inversion and electro-optical properties of SnO2 thin films synthesized by sol-gel technique

Al doped SnO₂ thin films have been synthesized by a sol-gel dip coating technique with different percentages of Al on glass and silicon substrates. X-ray diffraction studies confirmed the proper phase formation in the films and atomic percentage of aluminium doping in the films was obtained by energy dispersive X-ray studies. SEM studies showed the particle sizes lying in the range 100–150 nm for the undoped films and it decreased with increase of Al doping. Optical transmittance spectra of the films showed high transparency (∼80%) in the visible region and the transparency increases with the increase of Al doping in the films. The direct allowed bandgap of the films have been measured for different Al concentration and they lie within the range of 3.87–4.21 eV. FTIR studies depicted the presence of Sn–O, Al–O, bonding within the films. The room temperature electrical conductivities of the films are obtained in the range of 0.21 S cm⁻¹ to 1.36 S cm⁻¹ for variation of Al doping in the films 2.31–18.56%. Room temperature Seebeck coefficients, S_RT of the films were found in the range +56.0 μVK⁻¹ to −23.3 μVK⁻¹ for variation of Al doping in the films 18.56–8.16%. It is observed that the Seebeck coefficient changes its sign at 12.05% of Al in the films indicating that below 12.05% of Al doping, SnO₂:Al behaves as an n-type material and above this percentage it is a p-type material.     

Sorption behavior of γ-irradiated α-Al2O3

Irradiation of α-Al₂O₃ (Corundum) was carried out in contact with acidic media and with different doses (100-to-2500 kGy) and dose-rates (0.9, 2.6 and 6.1 kGy·h⁻¹) of γ-rays. Simultaneously parallel experiments were carried out using the same procedure, but preheated at 150°C for two days and then irradiated without acidic media. The solid thus obtained was used to determine the effect of γ-irradiation on the sorption capacities of microamounts of fission products from strongly alkaline aqueous solutions of uranium. The results revealed that the effect of γ-irradiation of α-Al₂O₃ and the acidic media in which it is immersed, is associated with a stable matrix resistant to significant changes in the composition of the surface layer; whilst it seems that the effect of γ-irradiation of preheated α-Al₂O₃, is connected with changes of surface-OH groups strongly affected by heat treatment and irradiation dose.     

Rubidium-cationic conductance in the systems Rb2 ? 2xAl2 ? xAxO4 (A = P, V)

RbAlO₂-based solid solutions are synthesized in the systems Rb_{2 − x} Al_{2 − x} A _x O₄ (A = P, V). Temperature and concentration dependences of their conductance are studied; the rubidium-cationic character of the conductance is corroborated. The high ionic conductivity of the synthesized phases (∼5 × 10⁻³ S cm⁻¹ at 300°C, ∼2 × 10⁻² S cm⁻¹ at 700°C) is caused by (a) formation of rubidium vacancies as a result of the replacing of Al³⁺ ions by fivefold-charged cations of phosphorus or vanadium and (b) disordered crystal structure of γ-KAlO₂ type. The obtained data are compared with the results of the studying of similar systems. Original Russian Text ? G.Sh. Shekhtman, E.I. Volegova, E.I. Burmakin, 2009, published in Elektrokhimiya, 2009, Vol. 45, No. 4, pp. 495–499.     

Controllable synthesis of β-Mn2V2O7 microtubes and hollow microspheres

β-Mn₂V₂O₇ microtubes with a length of 15–25 μm, 2.5–3.5 μm external diameter, and ∼0.4 μm wall thickness, as well as β-Mn₂V₂O₇ hollow microspheres with an average outer diameter of 2 μm, were successfully synthesized in a suitable molar ratio of NH₄VO₃ and MnCO₃ powders via a hydrothermal process. X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the products, and the magnetic susceptibility curve was also measured. In the whole process, the concentration of Mn²⁺ cations derived from MnCO₃ dissolution plays a crucial role in the formation of β-Mn₂V₂O₇ microtubes and hollow microspheres.     

Highly transparent UV absorption TiO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript>-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> films without oxidation catalytic activity prepared by a room temperature sol–gel route

TiO₂-SiO₂-Fe₂O₃ films as new UV absorption material were prepared through an epoxide derived sol–gel route. The films were formed at room temperature by doping of a little amount of γ-Fe₂O₃ nanoparticles in TiO₂-SiO₂. The obtained films show advantages such as high stability, efficient absorption in the UV region, high transparency in the visible range, and low oxidation catalytic activity to organic materials. It was found that 2.3 nm γ-Fe₂O₃ nanoparticles doped films exhibit stronger UV absorption than the films doped with 5.1 nm particles because of the increased grain strain of the nanoparticles with smaller size. These advantages of the films guarantee the broad application of this inorganic UV absorption film in the protection of heat sensitive organic materials such as artworks.     

水热法制备氧化钇空心纳米花及其吸附性能

采用水热法制备单分散、粒径均一的碱式碳酸钇(Y(OH)CO3)前驱体,经过高温煅烧处理得到氧化钇(Y_2O_3)空心纳米花。通过傅里叶转换红外分析(FT-IR),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),X射线衍射(XRD),X射线能谱(XPS)以及N2吸-脱附等来表征样品,并研究了Y_2O_3空心纳米花吸附重铬酸钾(K2Cr2O7)的能力。实验结果表明:水热法制备的前驱体为Y(OH)CO3,经高温煅烧处理得到立方相Y_2O_3空心纳米花,尺寸约140 nm,比表面积为15 m2·g-1,讨论了Y_2O_3空心纳米花的形成机理。水热法制备的Y_2O_3空心纳米花对K2Cr2O7溶液的去除率可高达88.5%,吸附量为11.06 mg·g-1,约为Y_2O_3粉末的6倍。     

水热法制备氧化钇空心纳米花及其吸附性能

采用水热法制备单分散、粒径均一的碱式碳酸钇(Y(OH)CO₃)前驱体,经过高温煅烧处理得到氧化钇(Y₂O₃)空心纳米花。通过傅里叶转换红外分析(FT-IR),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),X射线衍射(XRD),X射线能谱(XPS)以及N₂吸-脱附等来表征样品,并研究了Y₂O₃空心纳米花吸附重铬酸钾(K₂Cr₂O₇)的能力。实验结果表明:水热法制备的前驱体为Y(OH)CO₃,经高温煅烧处理得到立方相Y₂O₃空心纳米花,尺寸约140 nm,比表面积为15 m²·g^-1,讨论了Y₂O₃空心纳米花的形成机理。水热法制备的Y₂O₃空心纳米花对K₂Cr₂O₇溶液的去除率可高达88.5%,吸附量为11.06 mg·g^-1,约为Y₂O₃粉末的6倍。     

Low temperature and size controlled synthesis of monodispersed γ-Fe<Subscript>2</Subscript>O<Subscript>3 </Subscript>nanoparticles by an epoxide assisted sol–gel route

Monodispersed γ-Fe₂O₃ nanoparticles were prepared by a procedure-simple and precursor-cheap route, epoxide assisted sol–gel method. The γ-Fe₂O₃ nanoparticles were obtained by the reaction of FeCl₂ in ethanol solution with propylene oxide to form the sol, following by the boiling of the solution. As compared with other metal ions of +2 formal charge, the unexpected acidity of FeCl₂ in ethanol solution assure the formation of sol. As an advantage, the unique chemistry of this route results in the low temperature of synthesis, leading to the extremely small particle size of 2.3 nm and non-aggregation state of the particles.     

Co-cation conduction of the (Na1-x K x )3.8M0.1P2O7 (M = Ca, Sr, Cd) solid solutions

Samples of systems (Na _1-x K _x )_3.8M_0.1P₂O₇ (M = Ca, Sr, Cd; 0 ≤x ≤ 1) are synthesized. It is established that solid solutions with the structure of γ-K₄P₂O₇ form in these systems. At room temperature, the solutions exist atx ≥ 0.7. In the calcium-containing system, they form a continuous series at temperatures exceeding ∼500°C. The co-cation character of conduction of the solutions is confirmed by measured transport numbers. The concentration dependences of the electroconductivity and its activation energy point to a polyalkali effect, which decreases with an increase in the M²⁺ ion radius. Partial conductivities of sodium and potassium cations in the (Na _1-x K _x )_3.8Ca_0.1P₂O₇ system are calculated and their dependences on the balance between alkali cations in the solid solution are discussed     

Strong visible up-conversion emissions and thermometric applications of Er<Superscript>3+</Superscript>–Yb<Superscript>3+</Superscript> codoped Al<Subscript>2</Subscript>O<Subscript>3</Subscript> prepared by the sol–gel method

The Er³⁺–Yb³⁺ codoped Al₂O₃ has been prepared by the sol–gel method using the aluminium isopropoxide [Al(OC₃H₇)₃]-derived Al₂O₃ sols with addition of the erbium nitrate [Er(NO₃)₃ · 5H₂O] and ytterbium nitrate [Yb(NO₃)₃ · 5H₂O]. The phase structure, including only two crystalline types of doped Al₂O₃ phases, θ and γ, was obtained for the 1 mol% Er³⁺ and 5 mol% Yb³⁺ codoped Al₂O₃ at the sintering temperature of 1,273 K. By a 978 nm semiconductor laser diodes excitation, the visible up-conversion emissions centered at about 523, 545, and 660 nm were obtained. The temperature dependence of the green up-conversion emissions was studied over a wide temperature range of 300–825 K, and the reasonable agreement between the calculated temperature by the fluorescence intensity ratio (FIR) theory and the measured temperature proved that Er³⁺–Yb³⁺ codoped Al₂O₃ plays an important role in the application of high temperature sensor.     

Hydrothermal synthesis, structure and property of nano-BaTiO3-based dielectric materials

A series of Ba_1-xSr_xTi_1-yZr_yO₃ (0≤x≤0.5, 0≤y≤0.4) and BA_1?xZn_xTi_1?ySn_yO₃ (0≤x≤0.3, 0≤y≤0.3) solid solutions were synthesized by low-temperature/low-pressure hydrothermal method below 170°C, 0.8 MPa. XRD pattern and cell parameters-composition figures of these prepared powders demonstrated that they are completely miscible solid solutions based on BaTiO₃. Furthermore, TEM showed that they have a shape of uniform, substantially spherical particles with an average particle size of 70 nm in diameter. The sintered ceramics of those powders doped by Sr²⁺ and Zr⁴⁺ or Zn²⁺ and Sn⁴⁺ have dielectric constant twelve times higher than and dielectric loss 1/6 those of pure BaTiO₃ phase at room temperature.