An ionic-polymer-metallic composite actuator for reconfigurable antennas in mobile devices.

In this paper, a new application of an electro-active-polymer for a radio frequency (RF) switch is presented. We used an ionic polymer metallic composite (IPMC) switch to change the operating frequency of an inverted-F antenna. This switch is light in weight, small in volume, and low in cost. In addition, the IPMC is suitable for mobile devices because of its driving voltage of 3 volts and thickness of 200 µm. The IPMC acts as a normally-on switch to control the operating frequency of a reconfigurable antenna in mobile phones. We experimentally demonstrated by network analysis that the IPMC switch could shift its operating frequency from 1.1 to 2.1 GHz, with return losses of than -10 dB at both frequencies. To minimize electrolysis and maximize the operation time in air, propylene carbonate electrolyte with lithium perchlorate (LiClO4) was applied inside the IPMC. The results showed that when the IPMC was actuated over three months at 3.5 V, the tip displacement fell by less than 10%. Therefore, an IPMC actuator is a promising choice for application to a reconfigurable antenna.

Photocatalytic degradation of rhodamine B by anchored TiO2 nanowires.

Rutile TiO2 nanowires anchored on silica were fabricated by annealing TiO2 nanoparticles dispersed on silicon or quartz substrate by means of a polystyrene nanosphere monolayer template at 1000 degrees C for 1 h without any catalyst. The diameter and length of the nanowires were 30-80 nm and 1-3 microm, respectively. The growth direction of the nanowires is [112]. The photocatalytic activities of TiO2 nanoparticles and anchored nanowires were evaluated. TiO2 nanowires had higher photocatalytic activity for rhodamine B than TiO2 nanoparticles.

The formation of TiO(2) nanowires directly from nanoparticles.

TiO(2) nanowires were fabricated by annealing TiO(2) nanoparticles on silicon substrate at 1000 degrees C in air. When a polystyrene nanosphere monolayer was used as a template to separate the TiO(2) nanoparticles, they could more easily react with the silicon substrate to form Ti(5)Si(3). The TiO(2) nanowires were formed upon further oxidation of Ti(5)Si(3). The diameters and lengths of TiO(2) nanowires were 30-80 nm and 1-3 microm, respectively. The nanowires had a rutile structure with the growth direction [112]. It is believed that the formation of TiO(2) nanowires involved a precipitation process in the mixture of SiO(2) and TiO(2). The nanowires show different photoluminescence behavior from that of the powder.

Synthesis and photoluminescence of amorphous Ca5Ge2O9 nanowires.

A new method to prepare amorphous Ca5Ge2O9 nanowires is demonstrated in the present study. Germanium nanoparticles with the size ranging from 10 to 50 nm were first prepared by a vapor condensation technique. Upon immersing the nanoparticles in Ca(OH)2 aqueous solution, hydrated Ca5Ge2O9 nanowires were formed rapidly. The phase was determined by X-ray diffraction, and the stoichiometry of Ca:Ge was further confirmed by energy-dispersive X-ray spectroscopic and inductively coupled plasma-mass spectrometric analyses. The diameter of nanowires varied from several tens to more than 100 nm, and the length increased with aging time up to the completion of reaction. After dehydrating at 400 degrees C, the nanowires became amorphous, and the stoichiometry of Ca:Ge remained unchanged. A blue-violet luminescence was detected from these amorphous nanowires. The emission band distributed from 300 to 550 nm, with the main peak locating at 380 nm. Ge-associated luminescence centers are proposed to be responsible for this emission. The formation of amorphous Ca5Ge2O9 nanowires may provide a new thinking to prepare other kinds of amorphous one-dimensional nanomaterials.