Advanced Materials Research Vol. 502

Abstract: The effect of loading of stainless steel fiber (SSF) and temperature on electrical resistivity of SSF/PA6 conductive polymer composites was investigated in this paper. The distribution of fibers in the composites was observed by means of scanning electron microscopy（SEM）. The experimental results show that the resistivity decreases closely along with the increase of SSF loading from 0 to 12 Wt. % and temperature from 20 to 200°C. It is shown by SEM that the fibers are dispersed homogeneously in the polyamide-6 matrix.

Abstract: Organic semiconductor thin films of aluminum (III) bis(2-methyl-8-quninolinato)-4- phenylphenolate (BAlq), -naphthylphenylbiphenyl amine (NPB), and tris(8-hydroxy-quinoline) aluminum (AlQ) for organic light-emitting diodes (OLEDs) were deposited by the vacuum sublimation technique. The optical properties in the UV-visible region of the thin films were investigated by optical transmittance and absorption spectra. The band gaps were obtained from direct allowed transitions at room temperature by means of the Tauc plots. The Urbach energy and the slope of Urbach edge were evaluated, respectively according to the Urbach-edges method. The thin film devices of sandwich structure were fabricated using these organic semiconductor materials, in addition, the effective carrier mobility, free carrier density, and electrical conductivity of the thin films were calculated in terms of the measured current-voltage characteristics of the devices.

Abstract: Zinc oxide (ZnO) thin films were deposited by RF magnetron sputtering on glass substrates employing a sintered ceramic target and pure argon gas. The influence of substrate temperature on microstructure and optical characteristics of the deposited films were investigated by X-ray diffractometer (XRD) and spectrophotometer. The results demonstrate that all the ZnO films have preferred orientation along (002) direction. The substrate temperature significantly affects the crystalline quality and optical characteristics of the ZnO thin films. With the increase of substrate temperature, the mean grain size, lattice spacing and optical bandgap of the films increase, the dislocation density and micro strain decrease, and the average transmitance in the wavelength range of the visible spectrum also increases.

Abstract: A novel electron trapping material of CaB₄O₇:Sm³⁺ was synthesized by high temperature solid-state reaction, and its characterization and luminescent properties were investigated at room temperature. The results indicate that ultraviolet light can be used as exciting source to store energy. After exposed under ultraviolet, the sample was stimulated by 980nm laser. As a result, an obvious luminescence at 556, 596 and 643 nm were detected. The photo-stimulated emission spectrum was three bands peaking at 562, 599 and 646 nm that are the characteristic emission of Sm³⁺ ions due to the f→f transitions ⁴G_5/2→⁶H_J (J = 5/2, 7/2, 9/2), respectively. The TL glow curve contains two overlapping glow peaks at around 541 and 598 K.was synthesized by high temperature solid-state reaction, and its characterization and luminescent properties were investigated at room temperature. The results indicate that ultraviolet light can be used as exciting source to store energy. After exposed under ultraviolet, the sample was stimulated by 980nm laser. As a result, an obvious luminescence at 556, 596 and 643 nm were detected. The photo-stimulated emission spectrum was three bands peaking at 562, 599 and 646 nm that are the characteristic emission of Sm3+ ions due to the f→f transitions 4G5/2→6HJ (J = 5/2, 7/2, 9/2), respectively. The TL glow curve contains two overlapping glow peaks at around 541 and 598 K.

Abstract: This paper is the Cauchy integral theorem and integral of complex function carried out a comparative analysis, summarized in the Cauchy integral theorem and Cauchy integral formula, higher-order derivative formula, residue theorem and the relationship between the derivations to be proved, the formula can be used in these areas, such as mechanics of materials.

Abstract: This paper is a combination of conditions and the knowledge of singular integrals, the integrand function analysis of the deformation, the singularity in the integral for a class on the path integral come up with a complex new formula for the solution,the formula can be used in these areas,such as mechanics of materials.

Abstract: A novel red-emitting NaSrPO₄:Eu³⁺ phosphor was prepared by a conventional solid-state reaction. The luminescence properties and temperature dependence of ₄:Eu³⁺ were investigated. The phosphor exhibited red luminescence under the near-UV excitation of 395 nm, corresponding to the ⁵F₀→⁷L₆ transition of Eu³⁺ ions, which matched well with the excitation wavelength of near-UV LED chips. The electronic transition due to ⁵D₀→⁷F₂ transition of Eu³⁺ ions is stronger than the magnetic dipole transition due to ⁵D₀→⁷F₁ of Eu³⁺ ions. Furthermore, Eu³⁺-doped NaSrPO₄ phosphor shows higher thermally stable luminescence comparable tocommercially available Y₃Al₅O₁₂:Ce³⁺ phosphor. All the investigated suggested that this newly developed phosphor could find applications in white light devise utilizing InGaN-based excitation in the near-UV chips.

Abstract: YVO₄ co-doped with Tm³⁺/Ho³⁺/Yb³⁺ were synthesized by the high temperature solid state method and the optical properties of phosphors were characterized. Intense visible emissions centered at around 475, 541 and 649 nm, originated from the transitions of Tm³⁺:¹G₄→³H₆, Ho³:⁵S₂/>:⁵F₄ →⁵I₈, Tm³⁺:⁵G₄→3F₄ and Ho³⁺:⁵F₅→⁵I₈, respectively, have been observed in samples upon excitation with a 980 nm laser diode, and the involved mechanisms have been explained.

Abstract: An efficient near-infrared (NIR) quantum cutting (QC) Tb³⁺ and Yb³⁺ co-doped phosphor Sr₃Gd(PO₄)₃ has been synthesized by conventional high temperature solid technique. Upon excitation of Tb³⁺ with a visible photon at 485 nm, two NIR photons could be emitted by Yb³⁺ through cooperative energy transfer (CTE) from Tb³⁺ to two Yb³⁺ ions. Excitation and emission spectra as well as fluorescence decay measurements have been carried out to examine the occurrence of cooperative energy transfer (CET ) from Tb³⁺ to Yb³⁺ ions. The result indicates Tb³⁺ and Yb³⁺ co-doped Sr₃Gd(PO₄)₃ is potentially used as down-converter layer in silicon-based solar cell.

Abstract: Ce³⁺ and Tb³⁺ co-doped Strontium Pyroborate phosphors were synthesized by the solid-state method. The luminescent properties of phosphors were investigated by using the photoluminescence emission and excitation spectra. Under the excitation of near ultraviolet (n-UV) light, Ce³⁺ and Tb³⁺ co-doped Strontium Pyroborate phosphors exhibited blue emission corresponding to the f-d transition of Ce³⁺ ions and green emission bands corresponding to the f-f transition of Tb³⁺ ions, respectively. In the Ce3+ and Tb3+ co-activated samples the Ce³⁺ ions strongly sensitize the luminescence of the Tb ions. The Ce³⁺ and Tb³⁺ co-doped Strontium Pyroborate phosphor could be considered as one of double emission phosphor for n-UV excited white light emitting diodes.