Mesoporous Silica Sputter‐Coated onto ITO: Electrochemical Processes,Ion Permeability,and Gold Deposition Through NanoPores

“Simple” silica films of 50 nm and 100 nm thickness are sputter‐coated onto ITO substrates and shown to be structured with in‐planed features of ca. 15 nm and pores <5 nm (based on GISAXS). In electrochemical measurements membrane pore effects are observed. The oxidation current for Fe(CN)₆^4? in aqueous KNO₃ strongly depends on the electrolyte concentration. Poly‐cationic poly(diallyl‐dimethylammonium) (PDDA) cannot enter these pores, but is adsorbed onto the outer surface of the silica film. During gold electrodeposition, PDDA causes growth of “discs”. Gold deposits adhere well and a comparison of glucose electrooxidation activity reveals significant improvements.     

High efficiency event-counting thermal neutron imaging using a Gd-doped micro-channel plate

An event-counting thermal neutron imaging detector based on 3 mol % nattGd2O3-doped micro-channel plate （MCP） has been developed and tested. A thermal neutron imaging experiment was carried out with a low flux neutron beam. Detection efficiency of 33% was achieved with only one doped MCP. The spatial resolution of 72μ m RMS is currently limited by the readout anode. A detector with larger area and improved readout method is now being developed.     

Heterodoped nanoflakes: synthesis and characterization of sulfur‐doped NbSe2 nanoflakes

Doping of NbSe₂ with heteroatoms is an effective way to tailor its properties. Here, solid phase synthesis process has been utilized for growing uniform and excellent crystalline nano‐NbSe₂ by sulfur dopant during the growing process. The sulfur‐doped mechanism of nano‐NbS_2xSe_2(1‐x)(x = 0.03∼0.2) has been investigated: the sulfur atoms not only replace the Se position but also intercalate in layer gap by one‐step reaction. In the structure of NbSe₂, the sulfur atoms replace the positions of Se atoms and then are located in the empty octahedral positions of van der waals gap between the NbSe₂ layers with the increase of sulfur content. The lubrication properties of the as‐prepared NbSe₂ and sulfur‐doped NbSe₂ powders as additives in HVI1500 base oil were discussed. The lubrication properties of base oil was improved by both NbSe₂ and sulfur‐doped NbSe₂. Furthermore, the lubrication properties of sulfur‐doped (0.1at%) NbSe₂ are better than those of pure NbSe₂ in HVI1500 base oil, which could be attributed to their thin laminated structure and the sulfur dopant.     

以UV胶为纤芯本底的CdSe/ZnS量子点光纤光致荧光光谱的传光特性

制备了一种以紫外（UV）固化胶为纤芯本底的CdSe/ZnS量子点掺杂光纤.通过测量不同掺杂浓度和光纤长度下的量子点光致荧光光谱,得到了荧光峰值强度与量子点掺杂光纤浓度和长度的关系,确定了UV胶纤芯本底下的量子点的吸收系数、合适的掺杂浓度和光纤长度.结果表明|UV胶在光纤中具有吸收小、收缩率低、与石英光纤包层折射率匹配、性能稳定等特点,是一种比较理想的实验室制备量子点光纤纤芯本底的材料.     

Low frequency sonocatalytic degradation of Azo dye in water using Fe-doped zeolite Y catalyst

Sonocatalytic degradation of acid red B (ARB) dye was investigated using Fe doped zeolite Y catalysts with the assistance of low frequency (20 kHz) ultrasonic irradiation. Low concentration of Fe ions from different precursors was loaded onto the zeolite using wet impregnation method. Catalytic degradation of ARB dye was found to be accelerated by the reaction between Fe (II) and Fe (III) ions and hydrogen peroxide (H₂O₂) generated in situ by the ultrasound-mediated dissociation of water molecules. Fe (II)/Y exhibited higher degradation efficiency at the beginning of the reaction but achieved almost similar degradation at the end of the process. The increase of pH significantly decreased the degradation efficiency of ARB dye and strongly affected the leaching and catalyst stability. The highest efficiency was achieved at an initial pH of 3 with nearly 100% degradation in less than 60 min. Both catalysts showed no significant changes in terms of their mean particle sizes before and after reaction. Finally, Fe (III)/Y showed better performance evaluated based on leaching of Fe and also catalyst reusability. Only minor physical changes occurred during the degradation process for four consecutive runs of reaction.     

Effects of carbon doping on chemical states of amorphous Ge2Sb2Te5, measured with synchrotron radiation

We fabricated and analyzed the chemical states of carbon-doped (5.2–13.2 at.%) Ge₂Sb₂Te₅ thin films on Si substrates using high-resolution, X-ray photoelectron spectroscopy with synchrotron radiation. Thin films were completely amorphous and their phase-change temperature was 150 °C higher than for un-doped GST. As the carbon doping concentration increased, new chemical states of Ge 3d with 29.9 eV and C 1s with 283.7 eV core-levels were observed. The doped carbon was bonded only with Ge in GST and doping was saturated at 8.7 at.%.     

Transport characteristics of thermally degraded ZnO films doped with Al

The thermal degradation characteristics of Al doped ZnO (AZO) films, which were prepared by radio frequency magnetron sputtering at room temperature and subsequently annealed in air, were examined by making comparisons with those of the as-deposited and the vacuum-annealed AZO films. AZO films annealed in air at temperature higher than 300 °C exhibited severely degraded conductivity due to the decrease of carrier concentration and Hall mobility, which could be interpreted as grain boundary scattering from the thermally activated mobility behavior. Experimental observations, that vacuum-annealing of the as-deposited AZO film led to substantial reduction in carrier concentration and that subsequent vacuum-annealing of the air-annealed AZO film could not restore the carrier concentration unlike the restoration of Hall mobility up to 80%, led to a perception that substantial amount of free carriers in the as-deposited AZO film were generated from oxygen vacancies. It was proposed that ratios of the barrier height to the Fermi level, which were determined by taking into account the non-parabolic nature of the conduction band, could be used as a measure for the influence of grain boundary scattering on the overall electron transport mechanism in AZO films.     

Effect of Au interlayer thickness on the structural,electrical, and optical properties of GZO/Au/GZO multilayers

We report on the structural, electrical, and optical properties of Ga-doped ZnO/Au/Ga-doped ZnO (GZO/Au/GZO) multilayers as a function of Au interlayer thickness. Aggregated Au islands formed a continuous film as the thickness of the Au interlayer increased from 3 to 12 nm. Consequently, the sheet resistance, resistivity, and optical transmittance decreased with increasing Au interlayer thickness compared to a GZO single layer. However, a relatively high peak transmittance and a high figure of merit were obtained for an Au interlayer thickness of 9 nm. These results showed that the characteristics of GZO/Au/GZO multilayers could be improved by inserting an Au interlayer of optimized thickness. In addition, it indicated that the GZO/Au/GZO multilayer is the most promising candidates for indium free transparent conducting oxides (TCOs).     

Electric field-induced hole injection-enhanced photoluminescence in a N,N’-bis(3-methylphenyl)-N,N’-bis(phenyl)-benzidine-based emitter

Non-monotonic, asymmetrical electric field dependence of photoluminescence （PL） intensity is observed in a mono- layer sample of tris-（8-hydroxyquinoline） aluminum （A1Q） doped N,N＇-bis（3-methylphenyl）-N,N＇-bis（phenyl）-benzidine （TPD）. A possible model is proposed： the charge separation from the dissociated photoexcited excitons causes energy band bending in the organic films and improves the hole injection from the electrode, which brings about the extra fluorescence. This mechanism is further verified by a series of experiments using a series of samples, variously featuring symmetrical electrodes, block layers, and hosts with lower hole mobilities.     

Low‐wavelength emission of Nd‐doped lasers

This paper gives an overview of the results obtained with diode‐pumped Neodymium‐doped crystals operating below 900 nm. Operation at such low wavelengths requires considering the strong thermal population of the lower level of the laser transition. Based on a theoretical study and simulations, the paper presents the challenges related to the design of these three‐level lasers. Experimental results are given with Nd:YAG and Nd:vanadate crystals. It is explained how to deal with the line competition with emission at 946 nm or 912 nm. Finally, intracavity second‐harmonic generation is presented. The output powers reach a few hundred mW at wavelengths below 450 nm. Hence, the paper demonstrates the potential of Nd‐doped diode‐pumped solid‐state lasers for applications in the blue range, in replacement of gas lasers such as helium‐cadmium lasers.