Advanced Materials Research Vol. 717

Abstract: A new solid phase extractant silica aerogel immobilized with Cyanex 301 {bis (2,4,4-trimethylpentyl) dithiophosphinic acid} (SAWC) was prepared via a sol-gel method and investigated for the extraction of Zn (II) from aqueous solution by a batch extraction technique. It is found that SAWC can extract about 100% zinc at equilibrium pH 1.7. Prepared SAWC was characterized by FT-IR, BET, EDX and SEM which proved the presence of Cyanex 301 into silica aerogel. Moreover, the material is also easily regenerated and reused in the subsequent removal of Zn (II) in five cycles. Therefore, it could be concluded that it may perform as a solid phase extractant in the extraction of metal ions from the aqueous solution.

Abstract: The effect of soft X-ray irradiation to the Schottky diode properties was analyzed in this paper. The built-in voltage, leakage current, and work function of Schottky diode were investigated. The current-voltage characteristics of the Schottky diode are measured at room temperature. After irradiation at 70 keV for 55 seconds the forward current and leakage current are increase slightly. On the other hand, the built-in voltage is decrease from the initial value about 0.12 V. Consequently, this method can cause the Schottky diode has low power consumption. The results show that soft X-ray can improve the characteristics of Schottky diode.

Abstract: This paper analyzes the effect of X-ray irradiation on the electrical properties of Pt-doped p-n diode. X-ray energy irradiated on Pt-doped P-N diode with 70 keV with time 205 sec. After irradiations, the current-voltage (I-V) characteristics and capacitance-voltage (C-V) characteristics and carrier degeneration lifetime (τg) were investigated. The results show that the leakage current is slightly increased after the diodes were exposed X-ray and affect higher degeneration carrier lifetime. The effects after X-ray irradiation indicated that the defects of the diode have been changed.

Abstract: This paper presents the effect of X-ray irradiation on the electrical properties of Pt-doped P-N diode with X-ray energy 70 keV for 205 seconds. The results show that the radiation affected both reverse and forward current characteristics of P-N diode. The forward current is increased about 3 orders after radiation, while the leakage current is increased slightly after irradiation. Moreover, build-in voltage value is also changed after irradiation. The cause of parameters changing can be analyzed from carrier lifetime and series resistance. It can be seen clearly that X-ray irradiation technique are significant and can be used to improving electronic devices.

Abstract: Reverse leakage current (I_R) is a problem that degrade electrical characteristics and power diode effective. This paper presents the parameter extraction and analysis reverse leakage current of N-type silicon power-diodes with different geometries. All power diode were tested in 3perimeter and effective areas as follows: 0.58 cm, 0.98 cm,1.72 cm and 0.022 cm², 0.062 cm² 0.192 cm², respectively. We found the reverse leakage current increase with the larger junction perimeterto effective arearatio (P/A) that meaning the inverse leakage current increase with perimeter of the junction.

Abstract: Trivalent erbium ions, Er³⁺, in KY_1-xEr_xF₄ crystal produce up-converted photoluminescence (PL) band around 406 nm when excited by 488 or 532 nm photons. By using time-resolved spectroscopy, it was found that the up-conversion arises from the energy transfer processes between the excited Er³⁺ ions. Thermal behavior reveals that the 406 nm up-conversion is a phonon-assisted process. There is also a secondary up-conversion by level-crossing where a PL band around 520 nm is produced by the 532 nm excitation. High pressure causes the crystal to undergo a structural phase transition, as monitored by the PL it produces.

Abstract: The crystal structure of both samples has been solved by powder X-ray diffraction, data in the tetragonal space group I4/m (a= b= 5.55182 Å, c =7.86955 A⁰) for SrLaFeNi_0.5W_0.5O₆sample and (a=b= 5.49129Å, c= 7.82233Å) for CaLaFeNi_0.5W_0.5O₆ sample, and shows an almost perfect ordering between Ni²⁺ and W⁵⁺ cations at the B-site of the perovskite structure. The FTIR spectrometer used of the powders showed that the spectra of both are very similar, showing two strong and well-defined absorption bands, typical of perovskite materials.

Abstract: Non-enzymatic biosensors employing multi-walled carbon nanotube (MWNT) with highly dispersed Pt-M (M = Ru, Sn, and Au) nanoparticles (Pt-M@MWNT catalysts) were fabricated by radiolytic deposition. The Pt-M nanoparticles on the MWNTs were characterized by transmittance electron microscopy, elemental analysis, and X-ray diffraction. They were found to be well-dispersed and to exhibit alloy properties on the MWNT support. Electrochemical testing showed that these non-enzymatic biosensors had larger currents (mA) than that of a bare glassy carbon (GC) electrode and one modified with MWNTs. The sensitivity (μA mM^-1), linear range (mM), and detection limit (mM) (S/N = 3) of the glucose biosensor with the Pt-Ru, Pt-Sn and Pt-Au catalysts in PBS electrolyte were determined, respectively. The experimental results show that such biosensors can be applied to glucose detection in food chemistry field.

Abstract: We investigate the effect of central metal atom on the phthalocyanine (Pc) molecular crystals as intercalated with indium. As dopant, indium has physical interaction with some atom in the ring of Pc molecule and there is charge transfer between indium atom and Pc ring atom. Since In-doped Pc is a hole doping which increase positive charge carriers and the HOMO of ZnPc, CuPc, NiPc and MgPc are localized on the phthalocyanine ring, then, the central metal atom e.g. Zn, Cu, Ni and Mg are not directly involved with the charge transfer between indium dopant and their Pc molecule. The structural phase transition from α phase to β phase of ZnPc upon doping with indium is another evidence for the existing of charge transfer between dopant atom and matrix Pc molecule. A comparative experiment of optical absorption spectrum of each metal Pc reveals that the central metal atom will affect the forming of crystal structure whether will be α phase or β phase as intercalated with indium.

Abstract: A guided mode of positive and negative group index structure is essential to quantum optics for design and development of high efficiency optical devices which are useful to security optical communication system and to diverse applications such as Optical Time-Division-Multiplexing, Optical Switch, Laser, LED, Entangled Photon Source and Single Photon Source. Thus, we proposed to develop an efficient photon emission along line defect of two-dimensional honeycomb photonic crystal waveguide in the silicon slab. The honeycomb lattice of circular air holes on a silicon plate is simulated to obtain two nearest guided modes between positive and negative group index regimes. This significant property shows the potential applied guided modes of photonic crystal waveguide enhancing spontaneous emission for controlling photon emission between two resonance frequencies. Significantly, this work is oriented to produce the novel optical devices for control photon emission in the optical communication system. In addition to the honeycomb lattice, it can easily be made on a Si on insulator (SOI) wafer.