Solvent-vapor treatment induced performance enhancement of poly(3-hexylthiophene): methanofullerene bulk-heterojunction photovoltaic cells

The authors report enhanced poly(3-hexylthiophene) (P3HT):methanofullerene (PCBM) bulk-heterojunction photovoltaic cells via 1,2-dichlorobenzene (DCB) vapor treatment and thermal annealing. DCB vapor treatment can induce P3HT self-organizing into ordered structure leading to enhanced absorption and high hole mobility. Further annealing the device at a high temperature, PCBM molecules begin to diffuse into aggregates and together with the ordered P3HT phase form bicontinuous pathways in the entire layer for efficient charge separation and transport. Compared to the control device that is merely annealed, optical absorption, short-circuit current, and power conversion efficiency are increased for the DCB vapor-treated cell.

Preparation and transport properties of a bulk icosahedral quasicrystalline Ti45Zr35Ni17Cu3 alloy

A bulk alloy which consists of the single icosahedral quasicrystalline phase (I-phase) in Ti45Zr35Ni17CU3 alloy has been fabricated by mechanical alloying and subsequent pulse discharge sintering technique. Crystallographic structure analyses show that the bulk alloy is an I-phase. The transport properties of the bulk alloy are examined, and the results show that the room-temperature thermal conductivity is 5.347 W K-(1) m(-1), and the electrical conductivity decreases with increasing the temperature from 300 to 450K. The Seebeck coefficient is negative at the temperature range from 300 to 360K, and changes to positive from 370 to 450K. Hall effect measurements indicate the bulk I-phase alloy has a high carrier concentration. The specific heat capacity increases when the temperature increases from 280 to 324 K.

Calculation of bulk modulus on carbon nitrides with chemical bond method

The bulk moduli of some superhard materials were calculated by using the chemical bond method. For simple crystals, such as diamonds, c-BN, SiC, Si, BP, and Ge, the calculated results agree with experimental and theoretical values. For crystals of complex structure, such as beta-BC2N crystal and various structural C3N4 crystals, the results indicate that their bulk moduli are large, but do not exceed that of diamond.

Preparation and luminescent properties of cubic Eu3+ : Y2O3 nanocrystals and comparison to bulk Eu3+ : Y2O3

Y2O3:Eu3+ nanocrystals were prepared by combustion synthesis. The particle size estimated by X-ray powder diffraction (XRD) was about 10 nm. A blue-shift of the charge-transfer (CT) band in excitation spectra was observed in Y2O3:Eu3+ nanocrystals compared with bulk Y2O3:Eu3+. The electronic structure Of Y2O3 is calculated by density functional method and exchange and correlation have been treated by the generalized gradient approximation (GGA) within the scheme due to Perdew-Burke-Ernzerhof (PBE). The calculated results show that the energy centroid of 5d orbital in nanocrystal has increasing trend compared with that in the bulk material. The bond length and bond covalency are calculated by chemical bond theory. The bond lengths of Y2O3:Eu3+ nanocrystal are shorter than those of the bulk counterpart and the bond covalency of Y2O3:Eu3+ nanocrystal also has an increasing trend. By combining centroid shift and crystal-field splitting, the blue-shift of the CT band is interpreted.

Calculation of the bulk modulus of simple and complex crystals with the chemical bond method

The relation between the lattice energies and the bulk moduli on binary inorganic crystals was studied, and the concept of lattice energy density is introduced. We find that the lattice energy densities are in good linear relation with the bulk moduli in the same type of crystals, the slopes of fitting lines for various types of crystals are related to the valence and coordination number of cations of crystals, and the empirical expression of calculated slope is obtained. From crystal structure, the calculated results are in very good agreement with the experimental values. At the same time, by means of the dielectric theory of the chemical bond and the calculating method of the lattice energy of complex crystals, the estimative method of the bulk modulus of complex crystals was established reasonably, and the calculated results are in very good agreement with the experimental values.

Processing, microstructure and mechanical properties of W50Al50 bulk alloy obtained by mechanical alloying and hot-pressing

The Al50W50 alloy bulk bodies were fabricated by using mechanical alloying and hot-pressing in this work. The Al50W50 alloy had excellent thermal stability up to 1300 degreesC under vacuum and Its optimum microhardness, bending strength and compressive strength were 10.21 GPa, 570 MPa and 2.07 GPa, respectively.

Synthesis of novel maleimide-terminated thioetherimide oligomer and its bulk copolymerization with reactive solvents

This paper reports the synthesis of a novel maleimide-terminated thioetherimide oligomer and its copolymefization with reactive solvents bearing vinyl. Starting from 3-chlorophthalic anhydride and 4-chlorophthalic anhydride, 2,2',3,3'-thiodiphenyl tertracaboxylic dianhydride (3,3'-TDPA) and 3,3',4,4'-thiodiphenyl tertracaboxylic dianhydride (4,4'-TDPA) were synthesized. Thereby, a novel maleimide-terminated thioetherimide oligomer was prepared from. 3,3-TDPA, 4,4'-TDPA, 3,3'-dimethyl-4,4-diaminodiphenylmethane (DMMDA) and maleic anhydride. Binary and ternary copolymer resin were derived from corresponding binary and ternary homogeous solution consisting of thioetherimide oligomer, reactive solvent N-vinylpyrrolidone (NVP) or N,N'-dimethylacrylamide (DMAA) and divinylbenzene (DVB) as modifier, initiated either by gamma ray irradiation or by benzoyl peroxide (BPO). Thermal and mechanical properties of copolymer resin are determined and compared in terms of the kind of reactive solvent, addition of modifier DVB. The effect of initiation approach on property of final copolymer resin were studied. Phase separation and sub-transition of ternary copolymer resin induced by BPO are observed, which could be accounted for by thermal movement of DMAA molecules during thermal initiation.

Preparation and optical properties of trivalent europium-doped bulk and nanocrystalline SrY2O4

The nanocrystalline Sry(2)O(4):Eu3+ was prepared by a poly(vinyl alcohol) (PVA)+glycine-assist combustion method. The results of x-ray diffraction indicate that the resulting Sry(2)O(4):Eu3+ nanocrystals have much broader and less intense peaks compared with those in bulk material. The charge-transfer bands in Sry(2)O(4):Eu3+ nanocrystals shift to higher energies in contrast to those in bulk material. The spectral results revealed that in bulk SrY2O4: Eu3+ the Eu3+ ions occupied three nonequivalent sites, with one at the Sr site: one at the Y(1) site and another at the Y(2) site, while in nanocrystalline SrY2O4: Eu3+, the Eu3+ ions occupied only two nonequivalent sites; one at the Y(1) site and the other at the Y(2) site. Finally, by theoretical calculation and analysis, the analyzed results are in reasonable agreement with our experimental results.

Carbon ceramic electrodes bulk-modified with nanoparticles of ferrocenebutyrate-intercalated Mg-Al layered double hydroxide

Ferrocenebutyrate-intercalated layered double hydroxide (FcLDH) was prepared by the coprecipitation method and characterized by PXRD, FTIR, TEM and elemental analysis. FcLDH nanoparticles in deionized water were deposited onto the surface of graphite powder to yield graphite powder-supported FcLDH, which was subsequently dispersed into methyltrimethoxysilane-derived gels to fabricate surface-renewable, stable, rigid carbon ceramic electrodes containing the electroactive ferrocenyl group. Cyclic voltammetric study revealed that peak currents of the FcLDH-modified electrode were diffusion-con trolled in 0.1 mol l(-1) KCl aqueous solution. In addition, the formal potential of the modified electrode is related to the activity of chloride ion with a Nernst slope of 56 mV per decade.

Sol-gel derived carbon ceramic electrode bulk-modified with tris(1,10-phenanthroline-5,6-dione)iron(II) hexafluorophosphate and its use as an amperometric iodate sensor

A surface-renewable tris (1,10-phenanthroline-5, 6-dione) iron (II) hexafluorophosphate (FePD) modified carbon ceramic electrode was constructed by dispersing FePD and graphite powder in methyltrimethoxysilane (MTMOS) based gels. The FePD-modified electrode presented pH dependent voltammetric behavior, and its peak currents were diffusion-controlled in 0.1 mol/L Na2SO4 + H2SO4 solution (pH = 0. 4). In the, presence of iodate, clear electrocatalytic reduction waves were observed and thus the chemically modified electrode was used as an amperometric sensor for iodate in common salt. The linear range, sensitivity, detection limit and response time of the iodate sensor were 5 x 10(-6)-1 x 10(-2) mol/L, 7.448 muA.L/mmol, 1.2 x 10(-6) mol/L and 5 s, respectively. A distinct advantage of this sensor is its good reproducibility of surface-renewal by simple mechanical polishing.

Sol-gel-derived carbon ceramic composite electrodes bulk-modified with 1 : 12-silicomolybdic acid

1:12-Silicomolybdic acid (SiMo12) doped carbon ceramic composite electrodes were fabricated by incorporating SiMo12 and graphite powder in a methyltrimethoxysilane-based gel and characterized by cyclic and square-wave voltammetry, It was demonstrated that the chemically modified electrodes were suitable for electrocatalytic reduction of bromate, The electrodes had the remarkable advantage of surface renewal owing to bulk modification, as web as simple preparation, good mechanical and chemical stability and reproducibility.

Sol-gel-derived graphite organosilicate composite electrodes bulk-modified with Keggin-type alpha-germanomolybdic acid

A novel inorganic-organic hybrid material incorporating graphite powder and Keggin-type alpha -germanomolybdic acid (GeMo12) in methyltrimethoxysilane-based gels has been produced by the sol-gel technique and used to fabricate a chemically bulk-modified electrode. GeMo12 acts as a catalyst, graphite powder ensures conductivity by percolation, the silicate provides a rigid porous backbone, and the methyl groups endow hydrophobicity and thus limit the wetting section of the modified electrode. The GeMo12-modified graphite organosilicate composite electrode was characterized by cyclic and square-wave voltammetry. The modified electrode shows a high electrocatalytic activity toward the reduction of bromate, nitrite and hydrogen peroxide in acidic aqueous solution. In addition, the chemically-modified electrode has some distinct advantages over the traditional polyoxometalate-modified electrodes, such as long-term stability and especially repeatability of surface-renewal by simple mechanical polishing.

Chemiluminescent determination of luminol and hydrogen peroxide using hematin immobilized in the bulk of a carbon paste electrode

A new method for immobilization of a chemiluminescent reagent is presented. It is based on immobilizing hematin, a catalyst for luminol reaction, in the bulk of a carbon paste electrode. Bulk-immobilization allows renewal of the surface by simple polishing or cutting to expose anew and fully active surface in the case of fouling or deactivation by other means. By using a hematin-modified carbon paste electrode, the applied potential shifted negatively compared with that of unmodified carbon paste electrode or a glassy carbon electrode. The shift in potential changed the reaction processes and effectively stabilized the chemiluminescent signal during successive measurements. Under this condition, the signal was stable during 3 hours of continuous operation. The log-log plots of the emitted light intensity vs. luminol concentration and hydrogen peroxide concentration were linear over the region 10(-8)-10(-3) mol L-1 with a correlation coefficient of 0.999 and 3.9 x 10(-6)-10(-3) mol L-1 with a correlation coefficient of 0.994, respectively. Application of this method for other chemiluminescent and bioluminescent systems is suggested.