Advanced Materials Research Vols. 306-307

Abstract: Poly(N-(9-fluorenylmethoxycarbony)-glycine) (PFG) film was first synthesized on platinum wire by direct anodic oxidation of N-(9-fluorenylmethoxycarbony)-glycine (FG) in boron trifluoride diethyl etherate (BFEE). The oxidation potential of FG in BFEE was only 0.4 V vs. Pt. Therefore, BFEE can be an ideal supporting electrolyte for polymerization of FG. Scanning electron microscopy showed the morphology of PFG. The structure of PFG film was studied by FT-IR spectroscopy.

Abstract: 1-3 polymer-based piezoelectric composites were fabricated using epoxy as matrix by the cut-filling method. The influences of shape parameter on properties of the piezoelectric composite, which include the unit cross-sectional area and the aspect ratio w/t were analyzed. The results indicate that with the increasing of the unit cross-sectional area, the quality factor value Q_m increases and the hydrostatic piezoelectric voltage g_h increases and then goes down rapidly while the PMN volume fraction φ(PMN) is kept under the 50%. When the φ(PMN) is 60%, g_h is decreased. The trend of the hydrostatic figures of merit d_h·g_h is similar with g_h as the change of the unit cross-sectional area, but the value is different. In the 60% PMN volume fraction, the optimal value of the d_h·g_h is chosen. With the increasing of the w/t, the hydrostatic pressure sensitivity M_h, the d_h·g_h values and the Q_m values are all decreased rapidly, and the thickness electromechanical coupling factor k_t is increased. In other words, the test results show that the smaller of unit cross-sectional area and thinner of thickness, the more helpful for frequency bandwidth and sensitivity when it is used in transducer.

Abstract: A piezoelectric ceramic(lead niobium lithium zirconate titanate, P(LN)ZT), sulphoaluminate cement and polymer were used to fabricate polymer modified cement based piezoelectric composites by cut-filling technique. The influence of P(LN)ZT volume fraction on the electromechanical properties and acoustic impedance of composite was investigated. Comparing with P(LN)ZT Piezoelectric ceramic, the vibration at thickness mode of 1-3 type piezoelectric composite is strengthened, and the electromechanical quality factor is reduced. When P(LN)ZT volume fraction is 30.86%, the acoustic impedance value is 8.24 M rayl, which is close to that of the concrete (9.0 M rayl), and this is suitable for the non destructive inspection.

Abstract: We optimized the gallium nitride(GaN)photocathode’s structure in three aspects for higher quantum efficiency. AlN is used to replace GaN as the buffer layer, which can act as potential barrier to reflect electrons back to surface. The optimal thickness of emission layer is calculated as 162.5nm, and considering the graded doping profile, we optimized the thickness as 180nm. Three built-in electric fields are introduced by Mg graded doping, and the intensities of the high fields are calculated to give the quantitive results of their influence on quantum efficiency. After surface cleaning and activation, quantum efficiency of the optimized sample was greatly increased and the highest value of 56% was achieved at 5.20eV. More quantum efficiency enchancement is possible by further optimizing the photocathode structure.

Abstract: In view of the influence of the projected range, the range straggling, and the lateral deviation of ions in materials on the property of photoelectric integration devices fabricated by ion implantation, the mean projected ranges and range straggling for energetic 200 – 500 keV neodymium (Nd) ions implanted in silicon-on-insulator (SOI) at room temperature were measured by means of Rutherford backscattering followed by spectrum analysis. The measured results are compared with Monte Carlo code (SRIM2006) predictions. Our results show that the measured values of the mean projected range R_p are good agreement with the SRIM calculated values; for the range straggling ΔR_p, the difference between the experiment data and the calculated results is much higher than that of R_p.

Abstract: Poly[N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine] (PN9FPA) films with good fluorescence properties and good solubility were prepared electrochemically by direct anodic oxidation of N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine (N9FPA) in boron trifluoride diethyletherate (BFEE). The structures of the monomer and the polymers were characterized and evaluated with IR. The fluorescence spectra indicated that PN9FPA films were blue-light emitters.

Abstract: An electroanalysis method of determining Chloramphenicol (CAP) based on the eletrocalysis property of DNA-hydroxyapatite modified electrode (dsDNA/HAp/GCE) was setted up. In KH₂PO₄-Na₂HPO4 buffer solution with pH 6.0 cotaining 0.1 mol·L^-1 KCl, the peak current was proportional to the concentration of CAP in the range of 2.80 × 10^-7 to 3.60 × 10^-6 mol·L^-1, with a detection limit of 1.35 × 10^-7 mol·L^-1. The linear regress equation was i_p (μA) = 5.865 + 0.4784 c (µmol·L^-1), and the linear correlation coffcient was 0.9942. The method has been successfully applied to the quantitative analysis of CAP in real Chloramphenicol eye drops samples, which totally meet the demand of microanalysis. The relative standard deviation samples analysis results was 1ess than 3%.

Abstract: A new type rhodanine ramification 3-(4'-methoxyphenyl)-5 (2'- arsenoxylphenylazo)- rhodanine (4MORAAP) was prepared as fluorescent reagent in this paper. A new pectrofluorimetry method was proposed to determine the trace bismuth based on the reaction between potassium periodate and 4MORAAP. The fluorescence intensity was found to be quenched by the oxidation of 4MORAAP by potassium periodate with bismuth as catalyst in the buffer medium of potassium hydrogen phthalate-sodium hydroxide (pH=5.2). Under the optimum conditions, the fluorescent intensity was correlated to be linear with the concentration of bismuth over the range of 2.0×10^-7-1.8×10^-6 g×L^-1 and the detection limit was 2.9×10^-8 g×L^-1. The relative standard deviation (RSD) was 2.4 % for determined1.0×10^-6 g×L^-1 bismuth (n=11). The method was proved to be sensitive and selective and was successfully applied to determine trace bismuth in domestic water

Abstract: Continuous monolayer graphene sheet with large area has been synthesized via chemical vapor deposition (CVD) method using liquid hydrocarbon as precursor. Synthesis parameters including growth substrate and growth time have been investigated to assess their influence on monolayer graphene synthesis. Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) reveal that the number of layers and quality of graphene sheet depend greatly on the varied synthesis parameter. The study could be used to improve understanding the growth of graphene by CVD method in order to meet the needs of graphene in various electronic applications.

Abstract: Si-Cu alloys have been prepared by electroless depositions with different process. Si-Cu/MCMB materials have been prepared by carbonization of the mixture of Si-Cu, MCMB and mesophase pitch. The influences of electroless deposition condition and heat-treatment temperature on the anodic performance of Cu-Si/MCMB have been studied. Compared with Si/MCMB, Si-Cu/MCMB has more stable cyclical performance. Furthermore, the Si-Cu/MCMB sample produced by cleaning and then electroless deposition on Si shows the better anodic performance than the Si-Cu/MCMB sample produced by direct electroless deposition on Si, because the former sample has more Cu contents than the latter sample.