Improved method for preparation of anhydrous silica by microwave irradiation with spectroscopic characterization and toxicity assay

Amorphous anhydrous silica SiO_{2 (mw)} (99.99%) is successfully synthesized through microwave irradiation technique and time of reaction is reduced up to 1 h. The dehydration phase study of Si–water, Si–OH, Si–O–Si networking, elemental analysis and surface morphology was carried out by FTIR, FTNIR, SEM and EDAX spectroscopic techniques. The broad absorption stretching and bending of Si–OH and H₂O at 3695.38–2832.96 cm^? 1, 1638 cm^? 1 and 1191.20–1017.14 cm^? 1 completely disappeared and appearance of new bands at 946.93 and 797.63 cm^? 1 confirmed the amorphous anhydrous silica with Si–O–Si networking. The SEM images of SiO_{2 (mwc)} described the smooth and fine particle texture and confirmed 99.99% Si–O–Si networking of anhydrous silica. The 99.99% purity was verified by EDAX spectra which exhibited sharp signals only for oxygen and silicon. Toxicity against Monomorium minimum and Tribolium castaneum with 100% mortality and LT₅₀ 91 min and 7.5 h respectively is being reported. It can be used for long storage of grains in the future.     

Synthesis and in vitro evaluation of toxicity of silica-coated magnetite nanoparticles

Magnetic iron oxide nanoparticles properly coated with silica may be interesting in molecular biology, particularly as an auxiliary diagnostic material in biomedicine. This paper describes the coating of superparamagnetic magnetite nanoparticles with amorphous silica by sol–gel process using tetraethoxysilane. The physical–chemical characterization of the magnetite powder before and after silica-coating was performed by X-ray diffraction, Fourier-transform infrared, and zeta potential. The in vitro biocompatibility of the samples was analyzed by the viability/proliferation and collagen secretion capability of incubated osteoblasts in the presence of the composites. In summary, it was demonstrated that osteoblast viability decreased to about 20% in the presence of silica-coated magnetite nanoparticles when compared to the control group result. Moreover, the silica-coated magnetite nanoparticles did not alter osteoblast collagen secretion. The in vitro preliminary evaluation showed that silica-coating magnetite nanoparticles did not produce any severe alteration in biocompatibility. Further investigations are required to better understand the biocompatibility of silica-coated magnetite nanoparticles in biomedical applications.     

Synthesis and structural characterization of amorphous nano-sized SiBONC ceramic powders via polymer pyrolysis

SiBONC ceramic powders have been prepared via a polymer pyrolysis route using silicon tetrachloride (SiCl₄), benzaldehyde (PhCHO), boron trichloride (BCl₃) and aniline (PhNH₂) as starting materials. Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were performed to investigate the structural characteristics of the polymer precursor and the ceramic powders. The SiBONC ceramic powders in spherical shape with a mean diameter of 50 nm are amorphous and composed of B-N, Si-O, Si-C, and SiON_x groups. The SiBONC ceramic powders were sintered at 1700 °C to a dense material which still remained amorphous.     

Synthesis and magnetic properties of the SiO2–BaFe12O19 glass–ceramic composites

Samples of the magnetic glass–ceramics SiO₂–BaFe₁₂O₁₉ were obtained from mixtures of Fe₂O₃–BaSO₄–SiO₂–Na₂CO₃–CaCO₃ following a two-step route. The samples were characterized using XRD analysis and scanning electron microscopy, and their room temperature magnetization hysteresis loops were measured. It was found that the magnetic phase was completely developed in the precursor BaFe₁₂O₁₉ material when it was calcinated above 1000 °C. The size of the particles of the BaFe₁₂O₁₉ phase depends on the thermal treatment conditions and on the SiO₂ concentration. The magnetic data showed that the high value of the coercive magnetic field is preserved despite the fact that both the remanent and the saturation magnetizations diminish substantially.     

A new-type composite film of cholesteric liquid crystal doped with PCBM for laser-damage prevention in both visible and near-infrared region

Nowadays, with the increasing use of high-power laser, research and development of laser-damage prevention materials with multifunctional features and wideband wavelengths are urgent and indispensable. In the paper, cholestric liquid crystal (ChLC) is first proposed to be doped with a high-efficiency optical limiting material, 6, 6-phenyl C61-butyric acid methyl ester (PCBM), to fabricate a new-type laser-damage-prevention film. The ChLCs have the desired reflection wavelengths covering 750–2300 nm, which is an effective and potential candidate for the prevention of continuous or tuneable laser in near infrared (NIR) region. Meanwhile, the solubility of PCBM in LC and its nonlinear absorption property of are discussed, and it was proved that the good solubility of PCBM in LC contributed to the excellent nonlinear absorption of mixture (LC doped with PCBM). Taking advantages of this phenomenon, a novel composite film of ChLCs doped with PCBM is prepared by UV polymerization. As a result, the composite film not only performs broadband reflection in NIR region, but also exhibits a strong nonlinear absorption and excellent optical limiter properties in visible region, which proves the film's potential application in laser damage prevention.     

Magnetic properties of nanoparticles glass–ceramic rich with copper ions

The current study aimed at the assessment of CuO gradual addition on the crystallization behavior and magnetic properties of ferromagnetic glass ceramic in the system Fe₂O₃·CaO·ZnO·SiO₂. Ferromagnetic glass–ceramics with a high quantity of magnetite were designed to be crystallized in the system Fe₂O₃·CaO·ZnO·SiO₂. The influences of gradual addition of CuO and melting temperature on the sequence of crystallization and magnetic properties were studied. The X-ray diffraction patterns showed the presence of nanometric magnetite crystals in a glassy matrix after direct cooling from the melt without any additional heat treatments. Increasing the melting temperature resulted in an increase in the magnetite crystallization. The addition of up to 20 g CuO/100 g batch composition revealed a decreasing effects in both endo- and exothermic values, whereas, the same values were inversely increased with increasing the CuO addition to 30 g. In general, increasing the CuO amounts greatly enhanced the crystallization of magnetite. A significant amount of delaffosite (CuFeO₂) was unexpectedly detected and increased by increasing both the added amount of CuO and the treatment temperature. The XRD results detected some traces of cuprite (Cu₂O) in the samples of high CuO content. The TEM results reflected the precipitation of nano-magnetite crystals in the 2–10 nm size range. Magnetic hysteresis cycles were analyzed using a vibrating sample magnetometer with a maximum applied field of 20 kOe at room temperature in quasi-static conditions. From the obtained hysteresis loops, the saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (Hc) were determined.     

Synthesis and structure of iridium complex with thiocarbamide

A single crystal of the [Ir(Thio)₂Cl₄][Ir(Thio)₄Cl₂] compound synthesized by the reaction of K₃[IrCl₆] with thiocarbamide (Thio, SC(NH₂)₂) in a microwave field is investigated using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with space group Cc(C _s ⁴ ). The unit cell parameters are as follows: a = 13.554(1) Å, b = 8.251(1) Å, c = 24.992(2) Å, β = 92.58(1)°, V = 2791.87(10) ų, and Z = 4. The compound has an island structure with two crystallographically independent iridium atoms. Thiocarbamide is coordinated to the central atom through the sulfur atom. The coordination sphere of the Ir(1) atom involves two Cl atoms and four S atoms, whereas the coordination sphere of the Ir(2) atom consists of four Cl atoms and two S atoms. The assignment of the bands in the IR absorption spectrum of the synthesized compound is presented. The thermal behavior of the compound in air is investigated.     

Mechanism of crystallization of fast fired mullite-based glass–ceramic glazes for floor-tiles

The mechanism of crystallization from a B₂O₃-containing glass, with composition based in the CaO–MgO–Al₂O₃–SiO₂ system, to a glass–ceramic glaze was studied by different techniques. Glass powder pellets were fast heated, simulating current industrial tile processing methods, at several temperatures from 700 to 1200 °C with a 5 min hold. Microstructural study by field emission scanning electron microscopy revealed that a phase separation phenomenon occurred in the glass, which promoted the onset of mullite crystallization at 900 °C. The amount of mullite in the glass heated between 1100 and 1200 °C was around 20 wt%, as determined by Rietveld refinement. The microstructure of the glass–ceramic glaze heated at 1160 °C consisted of interlocked, well-shaped, acicular mullite crystals longer than 4 μm, immersed in a residual glassy phase.     

Thermooptical excitation of sound by Bessel light beams in crystalline media with internal stress

The thermooptical excitation of sound by Bessel light beams in crystalline media with internal stress has been studied. The dependence of the thermoelastic coupling coefficient, which is due to the modulated absorption of laser radiation, on the initial strain in a crystalline sample is taken into account. The expression for the photoacoustic signal amplitude is obtained, and it is shown that, in the range of high modulation frequencies of TE modes of Bessel light beams, resonant phenomena occur which can be used to increase the resolution of laser photoacoustic diagnostics of elastically strained crystals.     

Synthesis of the Copolymer Based on Diketopyrrolopyrrole with Didecyl Chain for OPVs

A new accepter unit, diphenylpyrrolo[3,2-b]pyrrole-2,5-dione with didecyl chain, was prepared and utilized for the synthesis of the conjugated polymer containing electron donor-acceptor pair for OPVs. The iDPP, part of the structure of a natural dye found in lichens, is the regioisomer of the known DPP with switched position of the carbonyl group and nitrogen atom. At the 4-positions of the N-substituted phenyl groups of 1,4-bis(4-butylphenyl)-pyrrolo[3,2-b]-pyrrole-2,5-dione unit in P-butyl, the butyl group was substituted with decyl group to increase solubility. The absorption spectrum of polymer with diphenylpyrrolo[3,2-b]pyrrole-2,5-dione unit exhibit two maximum peaks at about 365 and 542 nm. The spectrum of the P1 as the solid thin film shows absorption band with maximum peaks at 370 and 536 nm, and the absorption onset at 703 nm, corresponding to band gap of 1.76 eV. The oxidation and reduction potential onset of the synthesized polymer were estimated to be 0.84 and ?1.22 V, which correspond to HOMO and LUMO energy levels of ?5.64 and ?3.58 eV, respectively. The devices comprising P1 with PC₆₁BM annealed at 100°C showed a V_OC of 0.79 V, a J_SC of 1.75 mA/cm², and a FF of 0.31, leading to the power conversion efficiency of 0.43% under white light illumination (AM 1.5 G, 100 mW/cm²).     

High-pressure Synthesis and Properties of Manganates with Ilmenite Structure

A²⁺Mn⁴⁺0₃(A  Ni, Co, Mg, Cu) manganates with ilmenite structure have been obtained by solid phase synthesis at high pressure and temperature. The synthesis conditions for single phase samples have been determined, and investigations of the magnetic, electric, magnetooptic, and resonance properties were carried out.     

晶面可控氯氧铋的制备及光催化性能研究

利用水热法通过调节溶液的pH值制备了[001]晶面和[010]晶面的BiOCl.利用XRD、Raman、DRS及BET等对其结构及性能进行了表征,通过双酚A(BPA)降解及CO2还原实验考察了样品的光催化性能.研究表明,BiOCl[010]面催化剂的BPA降解速率及产生甲酸甲脂(MF)的速率分别是BiOCl [001]面催化剂的1.75倍、1.2倍.BiOCl[010]具有较高光催化活性的原因在于BiOCl[010]具有较大的比表面积和开放的孔道特性.     

Synthesis and characterization of nano ZnS doped with Mn

Nanocrystalline samples of Zn_1‐xMn_xS (x = 0.0, 0.02, 0.04) were synthesized by chemical precipitation method and characterized for magnetism. EPR studies showed an evidence of ferromagnetism around room temperature. Hysterisis from vibrating sample magnetometer supports the observation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Resonance excitation of polaritons by bulk electromagnetic waves in the layered systems with anisotropic substrates

The possible resonance excitation of surface electromagnetic waves by the bulk waves at the interface between a positive transparent uniaxial crystal and an isotropic medium has been predicted. The existence of the surface waves is provided by anisotropy of one of the boundary media. The tensor relation between the vector amplitudes of an exciting bulk electromagnetic wave and the excited surface wave is established. The ratio of the moduli of the tangential components of these amplitudes is analyzed as a function of the angle of incidence and the polarization of the bulk wave. The numerical calculations are performed for the surface waves at the interface between paratellurite TeO₂ and a KRS-6 (TlBr 30%-TlCl 70%) crystal.     

Effect of Si doping on near-infrared emission and energy transfer of Bismuth in silicate glasses

We have studied the effects of Si doping on the near infrared (NIR) luminescence observed in low Bi doped ( 0.1 mol% ) glasses and the energy transfer from Yb³⁺ to Bi. The broadband near infrared can only be observed when Si is introduced in the Bi-doped glass. The origin of this fluorescence can be attributed to Bi ions at low valence. Efficient energy transfer from Yb³⁺ to Bi NIR active ions is achieved by co-doping of Si. There is an increment of about ~ 29 times of the emission intensity from Bi-related active center as the Yb³⁺ concentration varies from 0 to 2.0 mol% and the amount of Si is 0.05 mol% under 980 nm excitation. The possible mechanism of energy transfer from Yb³⁺ to Bi is also discussed.     

Fast ion conducting phosphate glasses and glass ceramic composites: Promising materials for solid state batteries

Fast ion conducting (FIC) phosphate glasses and glass ceramic composites have gained considerable importance due to their potential applications in the fabrication of solid-state batteries and other electrochemical devices. We, therefore, present an overview on various types of FIC glasses and glass ceramic composites. Silver phosphate glasses doped with different weight percent of lithium chloride (1, 5, 10 and 15 wt.%) were synthesized by melt quenching technique. The Ag₂O–P₂O₅–(15 wt.%) LiCl glass exhibited the maximum electrical conductivity (σ = 8.91 × 10^? 5 S cm^? 1 at room temperature and 4.16 × 10^? 3 S cm^? 1 at 200 °C). Using this glass as an amorphous host material, glass–ceramic composites of Ag₂O–P₂O₅–(15 wt.%) LiCl:xAl₂O₃ (x = 5–50 wt.%) were prepared. The ionic transference number, electrical conductivity, ionic mobility and carrier ion concentration of the synthesized samples were measured. Ag₂O–P₂O₅–(15 wt.%) LiCl:(25 wt.%) Al₂O₃ composite system exhibited the maximum σ value (σ = 3.32 × 10^? 4 S cm^? 1 at room temperature and 2.88 × 10^? 2 S cm^? 1 at 200 °C ). Solid‐state batteries using undoped Ag₂O–P₂O₅ glass, Ag₂O–P₂O₅–(15 wt.%) LiCl glass and glass ceramic composite containing 25 wt.% Al₂O₃ as electrolytes were fabricated. The open circuit voltage (OCV) values and discharge time of these cells were measured and compared. It is found that the glass ceramic composites show enhanced ionic conduction, better OCV value and discharge characteristics.     

Synthesis and Structure of Uranyl Succinate Complexes with Cyanoguanidine and Diethylacetamide

Crystallography Reports - [UO2(suc)(C2N4H4)2] · 2H2O (I) and [UO2(Deaa)4(H2О)][(UO2)2(C4H4O4)3] · 2Deaa (II) crystals (suc2– is succinate ion, C2N4H4 is cyanoguanidine, and...     

几种形貌硼酸钙的微波水热合成与表征

以硼酸、无水氯化钙、氢氧化钠为原料,通过添加不同类型的修饰剂及采取前期预置的措施,在微波水热条件下可控制备了纳米片状和由纳米片自组装的球状花、灯笼状的CaO·3B2O3·4H2O型硼酸钙,以及由纳米颗粒自组装的棒状的CaO·3B2O3·5H2O型硼酸钙.通过组成分析、X射线粉末衍射(XRD)、热重分析(TG-DTA)、扫描电子显微镜(SEM)等手段对产物的结构、性质和形貌进行了表征.结果表明,在320℃时,添加10wt;不同形貌的硼酸钙CaO·3B2O3·4H2O可使木粉的残重率比未添加硼酸钙的提高28; ～ 32;,说明硼酸钙纳米结构具有良好的阻燃性.     

Synthesis and characterization of mesogenic triphenylene-perylene dyads with phenoxy-alkoxy linkers

Three novel triphenylene-perylene dyads with phenoxy-alkoxy linkers (PDI-OPhO-C_n-O- TP₆, n = 6, 8, 10) have been synthesized and characterized by FT-IR, MS, ¹³C, and ¹H NMR. The mesomorphic properties of these compounds were investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). It was found that the dyads (PDI-OPhO-C_n-O-TP₆, n = 6, 8) only showed thermotropic columnar mesophase in the heating process, while the dyad (PDI-OPhO-C₁₀-O-TP₆) showed enantiotropic columnar mesophase in both heating and cooling processes.     

Dependence of photoluminescence properties on excitation power in ZnO and ZnCdO microrods

ZnO and ZnCdO microrods have been prepared through a chemical bath deposition method. The structure of microrods has been characterized using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Photoluminescence spectra were recorded for ZnO and ZnCdO microrods at different excitation powers. The intensity of UV emission is enhanced with increasing excitation power. The width of UV emission increases for spectra at higher excitation powers. In particular, the paper shows that the influence of excitation power on the shift of emission band for ZnCdO microrods is more remarkable than that of ZnO microrods with the increase of excitation power. The definite experimental evidence demonstrated that the temperature coefficient β of ZnCdO microrods is much larger than the temperature coefficient of ZnO microrods. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)