The unimorph actuator of the LaNi 5 thin film deposited on polyimide substrates can be expected as a sensor and/or a controller of hydrogen gas flux in various hydrogen-related devices, since controlling the hydrogen concentration in the film by pressure change drives this actuator reversibility. In this study, the effect of the palladium deposition was investigated on the mechanical response of this thin film actuator. It was shown that the initiating time (incubation period) for the actuation to be measured after hydrogen gas exposure was reduced from 100 to 1 s by the palladium deposition. This significantly improvement of the mechanical response was attributed to the change in the rate determining steps: the dissociation of hydrogen gas molecules on the sample surface for the sample without palladium deposition, and hydrogen diffusion in the LaNi 5 film for the palladium deposited sample. It was also suggested that the high permeability of hydrogen in palladium film at room temperature resulted in the high responsiveness.

We are now reporting that Mg-C-O-H compound which has a Mg hydroxide symmetry, Mg(OH)2, whose mineral name is Brucite, is an excellent electrical conductor with high optical transparency. We believe that this new material is the first non-oxide type transparent conductor. The compound has approximately 90% of optical transmission and conductivity of approximately 10 −2 Ωcm with 2.4 µm of thickness. The compound was fabricated through two consecutive processes. First Mg-C films were prepared by magnetron sputtering. Then, post-treatment was done to make the Mg-C react with moisture in the air. These processes yielded Mg(OH)2-C. In this paper, the fabrication processes and optical and electrical conductive properties of the compound will be reported and possible origin of the excellent properties will be discussed.

In this study, the effect of a platinum surface treatment on the mechanical response of a LaNi 5 thin film actuator deposited on polyimide substrates was investigated. Since this actuator could be reversibly driven by hydrogen pressure control, it could function as a sensor and/or controller of the hydrogen gas flux in various hydrogen related devices. In the experiments, the incubation period of the actuation after hydrogen gas exposure was reduced from 100 to 10 s by the platinum surface treatment. This significantly modified mechanical response is attributed to a switching of the reaction rate determining steps. The platinum treatment enhanced the decomposition rate of hydrogen gas molecules at the surface. The platinum treatment should bring about a change of rate determining step to a permeation/diffusion of the hydrogen atoms into the film.

Hydrogen storage alloy, accompanied by a volume expansion of more than 24 by hydrogenation, exhibits enormous high levels of expanding force. An actuator using this phenomena functioning by hydrogen pressure change may exhibit both drastically large fore and shape changes. Hydrogen storage alloy is, however, pulverized by the hydrogenation, therefore, thin film in about 1 mm thick of a hydrogen alloy was used as actuator material, which was not pulverized by the hydrogenation. Compositional dependence of LaNi x ( x＝3.8 to 6.5) on the actuation behavior was investigated in this study. The largest displacement was observed for the test device with the composition of LaNi 5 , which indicated the largest storage capacity for the hydrogen.

In this study, the effect of the platinum surface treatment on mechanical response of LaNi 5 thin film actuator deposited on polyimide substrates was investigated. Since this actuator could be reversibly driven by hydrogen pressure control, this actuator is expected as a sensor and/or controller of hydrogen gas flux in various hydrogen related devices.In the experiments, initiating time of the actuation after hydrogen gas exposure is reduced from 100 to 10 s by platinum sur face treatment. This significantly modified mechanical response is attributed to switching of the reaction rate determining steps. Dissociation of hydrogen gas molecules on the sample surface is considered to be changed to permeation/diffusion of hydrogen atoms in the film by the platinum treatment.