Effect of a fullerene derivative on the performance of TiO2-nanotube-based dye-sensitized solar cells.

Highly ordered TiO2 nanotube arrays were prepared by anodic oxidation of Ti foil in an application to dye-sensitized solar cells (DSCs). A fullerene derivative called PC61BM was used as a material for the surface modification of TiO2 nanotube arrays to improve the power conversion efficiency of DSCs Although open circuit voltages (Voc) were slightly decreased by PC61BM interlayer, short circuit current densities (Jsc) were increased and thus the power conversion efficiencies were improved. EIS (Electrochemical Impedance Spectroscopy) results showed superior properties for PC61BM-coated samples.

Crystal structure and spontaneous magnetism of BiFeO3 powder synthesized by hydrothermal method.

Single-phase BiFeO3 powder was successively synthesized by a low-temperature hydrothermal method. Scanning electron microscopy and transmission electron microscopy results showed that BiFeO3 powder had several hundred nanometers to micrometer-sized particles with a broad size distribution. BiFeO3 powder showed weak-ferromagnetic behavior with a small magnetization value (Ms approximately 20 memu/g) at room temperature. Rietveld refinement results for the crystal structure show the displacive disorder of the Fe-site(6a); the Fe-site(6a) splits into two pairs, Fe(1) and Fe(2) displaced by 0.9 angstroms from each other and these sites are partially occupied. Hence the O-site(18b) also splits into the two partially occupied sites forming a distorted FeO6 octahedras. The weak ferromagnetism observed in the hydrothermal BFO powder is ascribed to the displacive disorder of FeO6 octahedras resulting in an incomplete counterbalance between the antiferromagnetic sublattices of the Fe-ions.

Fabrication and gas sensing properties of hollow SnO2 hemispheres.

Close packed arrays of hollow SnO2 hemispheres were prepared using PMMA microspheres as sacrificial templates for subsequent sputter-deposition of SnO2 films, leading to a threefold enhancement in gas sensitivity compared to non-templated (flat) films.

Integration of coplanar (Ba,Sr)TiO3 microwave phase shifters onto Si wafers using TiO2 buffer layers.

In this paper, a Ba0.6Sr0.4TiO3 (BST) tunable phase shifter with TiO2 films as microwave buffer layer between BST and silicon (Si) substrates is presented. The TiO2 buffer layer is grown by atomic layer deposition (ALD) onto Si substrate followed by pulsed laser deposition (PLD) of BST thin films onto the TiO2 buffer layer. The phase shifter fabricated on BST films grown on TiO2/Si substrate shows a good figure of merit (FOM) of 75.4 degrees/dB by exhibiting improved tunablity while retaining an appropriate dielectric Q as compared to 55.1 degrees/dB of BST/MgO structure. The TiO2 buffer layer grown by ALD enables successful integration of BST-based microwave tunable devices with high resistive Si wafer.

The structure of water near platinum and its significance in water-adsorbent system: molecular dynamics study.

Water structure around hydrophilic adsorbents is expected to differ from normal water structure. In some cases, a change of water structure seems to significantly affect phenomena involved in water-adsorbent systems. To investigate this, we have performed molecular dynamic simulations of three systems, water between (111) surfaces of Pt, water between (100) surfaces of Pt, and pure water at 298 K. For the analysis of water structure, we concentrated on the five-membered ring (R5) structure and six-membered ring (R6) structure, which are the most probable in nature. For both (111) and (100) of Pt, the ratio of hexameric ring/pentameric ring (R6/R5) in semibound regions was higher than that of bulk water, as expected. The function of adsorbent ceramics was explained in terms of the change of water structure when they are used as biomaterials, support materials, etc. The obscure mechanisms for the effects of medicine stones, antioxidants, etc., were also discussed from this point of view.