The filled skutterudite compound of LayFeCo3.0Sb12 (y = 0-0.4) were prepared by in-situ spark plasma sintering(SPS) technology using Co, Sb, Fe and La powders. The results show that the skutterudite phase is predomina...
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The filled skutterudite compound of LayFeCo3.0Sb12 (y = 0-0.4) were prepared by in-situ spark plasma sintering(SPS) technology using Co, Sb, Fe and La powders. The results show that the skutterudite phase is predominant in all the samples with small amounts of Sb when 0 y [less-than or equal to] 0.3;the maximum filling fraction of La is 0.3 for LayFeCo3.0Sb12, The lattice constant and Seebeck coefficient increase with increasing La-filling, while the electrical conductivity and thermoelectric conductivity decrease. The power factor increases with the temperature. All the La-filling compounds of LayFeCo3.0Sb12 behave as p-type conduction. The LayFeCo3.0Sb12 compound has higher thermoelectric property when y is 0.3, the maximum value of the dimensionless figure of merit (ZT) is 0.56 at 773 K.
Ba0.5Sr0.5NbTi1-z O3 (BSNT, z = 0-4.12%) thin films were prepared by sol-gel method. The influences of trace element niobium (Nb) on the dielectric properties of the film were studied by means of impedance analyzer HP...
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Ba0.5Sr0.5NbTi1-z O3 (BSNT, z = 0-4.12%) thin films were prepared by sol-gel method. The influences of trace element niobium (Nb) on the dielectric properties of the film were studied by means of impedance analyzer HPAgilent 4294A. The dielectric constant (εR) is reduced, but dielectric loss (tanδ) is improved, for example, tan8 is reduced from 0.09 to 0.067 at 1 kHz, and Curie temperature Tm moves to lower temperature with the increasing amount of Nb. Better scattering frequency characteristics appear for the thin films with Nb in the range of from 2.0 MHz to 10 MHz. The microstructure of BSNT thin films was studied by XRD, TEM. The crystal structure of the BSNT thin films is tetragonal per-ovskit, and the grain size is decreased with the Nb content increasing. The ratios of c/a (crystalline cell parameters) of BSNT is changed, and the density is increased.
We present a comprehensive study of the photoexcitation dynamics in fluorenone-free and fluorenone-containing polyfluorenes both on the femtosecond and the millisecond time scale. In the fluorenone-free polyfluorene a...
We present a comprehensive study of the photoexcitation dynamics in fluorenone-free and fluorenone-containing polyfluorenes both on the femtosecond and the millisecond time scale. In the fluorenone-free polyfluorene a small amount of polarons are observed, which form instantaneously. Triplets are the dominant species on the ms time scale. In fluorenone-containing polyfluorenes a considerable fraction of the excitation energy is transferred to the fluorenone units, which act as energy sinks. Their lowest excited state is of charge-transfer nature and can dissociate into polarons, while no triplets are revealed.
Biaxial aligned YBCO films have been successfully deposited on Ag {110}〈110〉 textured polycrystalline substrates by metal-organic decomposition (MOD) method using Trifluoroacetate Salt (TFA). The influence of firing...
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Biaxial aligned YBCO films have been successfully deposited on Ag {110}〈110〉 textured polycrystalline substrates by metal-organic decomposition (MOD) method using Trifluoroacetate Salt (TFA). The influence of firing temperature and Ag surface defects on phase purity and texture, surface morphology of YBCO films was studied. Holding temperature at 900 ℃ for 30 min benefits to improve orientation and connectivity of YBCO films. The surface of YBCO films deposited on unpolished Ag substrate has many holes and stripes, which are parallel to the rolling stripe on Ag substrates. To eliminate the rolling stripe on the Ag surface, Ag substrates were polished prior to films deposition. The film grown on polished Ag substrates has a smooth surface and good connectivity of grains without parallel stripes. The YBCO films have an onset of transition around 90K and critical current densities of (15 000 A/cm^2.)
For the sake of objectivity of the interpretation in life cycle assessment (LCA), the concept and the design proposal of Standard Flow were put forward. Standard Flow was defined as the collection of related environme...
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For the sake of objectivity of the interpretation in life cycle assessment (LCA), the concept and the design proposal of Standard Flow were put forward. Standard Flow was defined as the collection of related environmental load parameters that represent the specific development degree of certain industrial process(es) by the function unit. A novel methodological approach called the Standard Flow Comparing, was developed for LCA. The indicator for potential of process improvement and its weighting factor were derived. To a certain degree the problem of the identification and selection of process development objects in LCA was solved. The concept of Standard Flow and the method of Standard Flow Comparing are introduced, formulized and analyzed.
More realistic simulations of the magnetic field and electron optical phase shift associated to pancake vortices in layered high-Tc superconducting specimen require a number of layers larger than 7, the practical uppe...
More realistic simulations of the magnetic field and electron optical phase shift associated to pancake vortices in layered high-Tc superconducting specimen require a number of layers larger than 7, the practical upper limit set by the discrete algebraic approach followed so far. This goal can be achieved by resorting to a continuum approximation of the screening layers above and below the one containing the pancake vortex. It is thus possible to increase the number of layers and to investigate more exotic vortex core structures than those represented by the pancakes pinned at tilted columnar defects. In particular it will be shown how recently observed dumbbell-like contrast features in the out-of-focus images of superconducting vortices forming a large angle with the specimen surfaces can be interpreted as due to a kinked structure of the pancakes.
The preparation process, structure feature and field electron emission characteristic of diamond films on nanocyrstalline diamond coating by the CVD method were studied. The field electron emission measurements on the...
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The preparation process, structure feature and field electron emission characteristic of diamond films on nanocyrstalline diamond coating by the CVD method were studied. The field electron emission measurements on the samples showed that the diamond films have lower turn-on voltage and higher field emission current density. A further detailed theory explanation to the results was given.
HPA was impregnated on mesoporous silica (SBA-15, MCM-41), commercial silica (ML369) and activated carbon, as well as on mesoporous carbons (CMK-1, CMK-3). The resulting materials were investigated by means of XRD, BE...
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