Enhanced Proton Conduction in Polymer Electrolyte Membranes as Synthesized by Polymerization of Protic Ionic Liquid-Based Microemulsions

Proton-conducting membranes were prepared by polymerization of microemulsions consisting of surfactant-stabilized protic ionic liquid (PIL) nanodomains dispersed in a polymerizable oil, a mixture of styrene and acrylonitrile. The obtained PIL-based polymer composite membranes are transparent and flexible even though the resulting vinyl polymers are immiscible with PIL cores. This type of composite membranes have quite a good thermal stability, chemical stability, tunability, and good mechanical properties. Under nonhumidifying conditions, PIL-based membranes show a conductivity up to the order of 1 x 10(-1) S/cm at 160 degrees C, due to the well-connected PIL nanochannels preserved in the membrane. This type of polymer conducting membranes have potential application in high-temperature polymer electrolyte membrane fuel cells.

Silica and alumina thin films grown by liquid phase deposition

This work demonstrates the condition optimization during liquid phase deposition (LPD) Of SiO2/GaAs films. LPD method is further applied to form Al2O3 films on semiconductors with poison-free materials. Proceeding at room temperature with inexpensive equipment, LPD of silica and alumina films is potentially serviceable in microelectronics and related spheres.

Net-like ferromagnetic MnSb film deposited on porous silicon substrates

MnSb films were deposited on porous silicon substrates by physical vapor deposition (PVD) technique. Modulation effects due to the substrate on microstructure and magnetic properties of the MnSb film's were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and measurements of hysteresis loops. SEM images of the MnSb films indicate that net-like structures were obtained because of the special morphology of the substrates. The net-like MnSb films exhibit some novel magnetic properties different from the unpatterned referenced samples. For example, in the case of net-like morphology, the coercive field is as low as 60 Oe. (c) 2006 Elsevier B.V. All rights reserved.

Porous InP array-directed assembly of InAs nanostructure

Fascinating features of porous InP array-directed assembly of InAs nanostructures are presented. Strained InAs nanostructures are grown by molecular-beam epitaxy on electrochemical etched porous InP substrate. Identical porous substrate with different pore depths defines different growth modes. Shallow pores direct the formation of closely spaced InAs dots at the bottom. Deep pores lead to progressive covering of the internal surface of pores by epitaxial material followed by pore mouth shrinking. For any depth an obvious dot depletion feature occurs on top of the pore framework. This growth method presages a pathway to engineer quantum-dot molecules and other nanoelements for fancy physical phenomena. (c) 2006 American Institute of Physics.

Porous ZnAl2O4 spinel nanorods doped with Eu3+: synthesis and photoluminescence

Eu3+-doped zinc aluminate (ZnAl2O4) nanorods with a spinel structure were successfully synthesized via an annealing transformation of layered precursors obtained by a homogeneous coprecipitation method combined with surfactant assembly. These spinel nanorods, which consist of much finer nanofibres together with large quantities of irregular mesopores and which possess a large surface area of 93.2 m(2) g(-1) and a relatively narrow pore size distribution in the range of 6 - 20 nm, are an ideal optical host for Eu3+ luminescent centres. In this nanostructure, rather disordered surroundings induce the typical electric-dipole emission (D-5(0) --> F-7(2)) of Eu3+ to predominate and broaden.

MnSb/porous silicon hybrid structure prepared by physical vapor deposition

MnSb/porous silicon hybrid structure was prepared by physical vapor deposition technique. The structure and surface morphology of the MnSb films were analyzed by X-ray diffraction and scanning electron microscope, respectively. The magnetic hysteresis loops were obtained by an alternative gradient magnetometer. Based on the measurements, only MnSb phase was found and the surface morphology was rough and island-like. MnSb thin films show ferromagnetism at room temperature. (C) 2003 Elsevier B.V. All rights reserved.

Photoluminescence enhancement of porous silicon by organic cyano compounds

A pronounced photoluminescence enhancement on chemically oxidized porous silicon was induced by a series of organic cyano compounds including 1,2-dicyanoethylene (CE), 1,3-dicyanobenzene (1,3-CB), 1,4-dicyanobenzene (1,4-CB), 1-cyanonaphthalene (1-CN), and 9-cyanoanthracene (9-CA). Photoluminescence enhancement effects were reversible for all compounds studies in this work. A dependence of photoluminescence enhancement on the steric effect and the electronic characteristics of these compounds and the structure of the porous silicon substrates were analyzed in terms of the photoluminescence enhancing factors. Surface chemical composition examined by Fourier transform infrared (FTIR) spectra demonstrated that the surface Si-H bonds were not changed and no new luminescent compounds were formed on porous silicon surface during adsorption of cyano compounds. A mechanism based on induced surface states acting as radiative recombination centers by cyano compounds adsorption was suggested.

Effects of molecular structures on the olfactory responses of phospholipid membranes to four alcohols

In order to understand the relationship between phospholipid molecular structures and their olfactory responses to odorants, we designed and synthesized four phosphatidylcholine analogues with different long hydrocarbon (CH) chains and selected three natural phospholipids with different head-groups. By using interdigital electrodes (IEs) as olfactory sensors (OSs), we measured the responses of the Ifs coated with these seven different lipid membranes to four alcohol vapors in a gas flow system. The Ifs voltage changes were recorded and the voltage-relative saturate vapor pressure (V-P/P degrees) curves were also plotted. It was found that with a methyl (-CH3) placed at the C-8 position in the 18-carbon chain, the olfactory responses could be improved about ten times and with conjugated double bonds (C=C) in the long chains, the sensitivity could be increased by 3 similar to 4 orders of magnitude. As to head-groups, choline is preferred over ethanolamine and serine in phospholipid structures in terms of high olfactory sensitivity: These results are expected to be useful in further designing and manufacturing lipid-mimicking OSs. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

Photoluminescence from Ge clusters embedded in porous silicon

Visible photoluminescence (PL) and Raman spectra of Ge clusters embedded in porous silicon (PS) have been studied. The as-prepared sample shows redshifted and enhanced room temperature PL relative to reference PS. This result can be explained by the quantum confinement effect on excitons in Ge clusters and tunnel of excitons from Si units of the PS skeleton to Ge clusters. One year storage in dry air results in a pronounced decrease in PL intensity but blue-shifted in contrast to reference PS. This phenomenon correlates to the size decrease of macerated Ce clusters and occurrence of "quantum depletion" in Ge clusters. Consequently, only excitons in Si units contribute to PL. (C) 1998 American Institute of Physics.

Effects of 9-cyanoanthracene and anthracene adsorption on the photoluminescence of porous silicon

The photoluminescence of porous silicon can be modified sensitively by surface adsorption of different kinds of molecules. A quite different effects of 9-cyanoanthracene and anthracene adsorption on the photoluminescence of porous silicon were observed. The adsorption of 9-cyanoanthracene induced the photoluminescence enhancement, while anthracene adsorption resulted in photoluminescent quenching. An explanation of the interaction of adsorbates with surface defect sites of porous silicon was suggested and discussed. (C) 1998 Elsevier Science S.A.

Fracture properties of silicon carbide thin films charcterized by bulge test of long membranes

The mechanical properties and fracture behavior of silicon carbide (3C-SiC) thin films grown on silicon substrates were characterized using bulge testing combined with a refined load-deflection model for long rectangular membranes. Plane-strain modulus E-ps, prestress so, and fracture strength s(max) for 3C-SiC thin films with thickness of 0.40 mu m and 1.42 mu m were extracted. The E, values of SiC are strongly dependent on grain orientation. The thicker SIC film presents lower so than the thinner film due to stress relaxation. The s(max) values decrease with increasing film thickness. The statistical analysis of the fracture strength data were achieved by Weibull distribution function and the fracture origins were predicted.

The improvement of thick oxidized porous silicon layer growth process - art. no. 60290S

Oxidizing thick porous silicon layer into silicon dioxide is a timesaving and low-cost process for producing thick silicon dioxide layer used in silicon-based optical waveguide devices. The solution of H2O2 is proposed to post-treat thick porous silicon (PS) films. The prepared PS layer as the cathode is applied about 10 mA/cm(2) current in mixture of ethanol, HF, and H2O2 solutions, in order to improve the stability and the smoothness of the surface. With the low-temperature dry-O-2 pre-oxidizations and high-temperature wet O-2 oxidizations process, a high-quality SiO2 30 mu m thickness layer that fit for the optical waveguide device was prepared. The SEM images show significant improved smoothness on the surface of oxidized PS thick films, the SiO2 film has a stable and uniformity reflex index that measured by the prism coupler, the uniformity of the reflex index in different place of the wafer is about 0.0003.

A silicon capacitive microphone based on oxidized porous silicon sacrificial technology

In this paper, a new capacitive microphone fabrication technology is proposed. It describes using the oxidized porous silicon sacrificial technology to make air gap and using KOH etching technique to make the backplate containing acoustic holes based on the principle that the heavy p(+)-doping silicon can be nearly etched in KOH solution. The innovation of the method is using oxidized porous silicon technology. The sensitivity of the fabricated microphone is from -55dB ( 1.78mV/Pa) to -45dB (5.6mV/Pa) in the frequency range of 500Hz to 25kHz. Its cut-off frequency is higher than 20kHz.