A nanoparticle catalyst of PtRuAu/C was synthesized by including an Au precursor in the radiolytic process for preparing a PtRu/C catalyst. Their methanol oxidation activity and electrochemical durability were measured by linear sweep voltammetry before and after potential cycling treatment. PtRuAu/C had a significantly higher durability than PtRu/C while maintaining a comparable high activity. The morphology and substructure of the nanoparticles were investigated by energy-dispersive x-ray spectroscopy, x-ray diffraction, and x-ray absorption fine structure spectroscopy. Metallic nanoparticles with diameters of about 2 nm were obtained; they probably had Pt-core/PtRu-shell structures. Transmission electron microscopy observations after potential cycling revealed that 2-nm-diameter nanoparticles containing Au did not coarsen, whereas nanoparticles without Au coarsened significantly to 3.7 nm. Some crystal defaults were observed in the coarsened particles, implying that the coarsening was caused by Ostwald ripening. The Au addition to catalyst particles consisting of PtRu inhibits coarsening and consequently improves the electrochemical durability.

In the process of developing electro-optic devices from ferroelectric z-cut LiNbO3 wafers, a repolarization throughout the wafer thickness occurs due to a localization of electric charges on the wafer. The repolarization not only generates microdomains causing light to scatter but also large defects in the crystal that become the origin of wafer fracture. The size of such defects is comparable to the wafer thickness (0.5 mm), and an anomaly in the chemical and crystalline structures can be found in them. X-ray diffractometry and x-ray photoelectron spectroscopy confirm that a chemical reduction in the defective region occurs.

Increasing demands for LiNbO3 (LN) optical waveguide devices installed into submarine and terrestrial fiber communication systems necessitate that high quality and long-term reliability (over 20 years) be established. In addition to general requirements for reliability in electrooptical devices, the LN devices need to assure of the dc-drift phenomena in the optical output signal. The dc-drift is caused by the complex electrical nature of constituent device materials; i.e. LN substrates and SiO2 buffer layers on LN. Results of theoretical and experimental investigations of the suppression of dc-drift are applied to the design of practical LN devices, and the devices have been in service for 4 years, as of this moment, without any failure. Here, problems on the dc-drift are discussed from the viewpoints of device reliability and actual fabrication processes.

A thermal diffusion process of Ti into a LiNbO3 substrate for optical waveguides has generally been carried out under a wet gas atmosphere in order to prevent undesirable Li outdiffusion. In this work, such thermal decomposition was confirmed to be significantly suppressed for an OH-free LiNbO3 substrate, even after a dry atmosphere annealing. No extra x-ray diffraction peak for LiNb3O8 was detected from the OH-free substrate after 10 h of annealing at 1000 °C in a dry O2. Furthermore, the surface morphology of this sample, and as well an unannealed one, were smooth. In a conventional LiNbO3 substrate containing many OH ions, subjected to a similar dry annealing, the presence of the LiNb3O8 phase and a surface coarsening were observed.