Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers, side surfaces facing each other of the electrode fingers having a plurality of protrusion portions and a plurality of recessed portions arranged in an extension direction of the electrode fingers, ends of the protrusion portions and the recessed portions narrowing.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers, side surfaces facing each other of the electrode fingers having a plurality of protrusion portions and a plurality of recessed portions arranged in an extension direction of the electrode fingers, ends of the protrusion portions and the recessed portions narrowing.

Abstract: An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes that is located on the piezoelectric substrate, includes a metal film, and excites a surface acoustic wave, the metal film being mainly composed of a metal having a melting point equal to or higher than a melting point of Pt, the metal film having a first region in which a crystal grain has a columnar shape and a second region that is located on and/or under the first region in a stacking direction and has less crystallinity than the first region or has an amorphous structure.

Abstract: Consumed hydrogen-off gas is discharged from a fuel cell via a hydrogen-off gas exhaust flow passage. Consumed oxygen-off gas is discharged from the fuel cell via an oxygen-off gas exhaust flow passage. The oxygen-off gas flowing through the oxygen-off gas exhaust flow passage and the hydrogen-off gas flowing through the hydrogen-off gas exhaust flow passage are mixed and diluted in a mixing portion. The gases mixed in the mixing portion flow into a combustor via a gas-liquid separator. The combustor, which includes a platinum catalyst, causes hydrogen contained in the mixed gases to react with oxygen by combustion and further reduces the concentration of hydrogen contained in the mixed gases. The mixed gases whose concentration of hydrogen has been reduced by the combustor is discharged to the atmosphere.

Abstract: Consumed hydrogen-off gas is discharged from a fuel cell via a hydrogen-off gas exhaust flow passage. Consumed oxygen-off gas is discharged from the fuel cell via an oxygen-off gas exhaust flow passage. The oxygen-off gas flowing through the oxygen-off gas exhaust flow passage and the hydrogen-off gas flowing through the hydrogen-off gas exhaust flow passage are mixed and diluted in a mixing portion. The gases mixed in the mixing portion flow into a combustor via a gas-liquid separator. The combustor, which includes a platinum catalyst, causes hydrogen contained in the mixed gases to react with oxygen by combustion and further reduces the concentration of hydrogen contained in the mixed gases. The mixed gases whose concentration of hydrogen has been reduced by the combustor is discharged to the atmosphere.

Abstract: Consumed hydrogen-off gas is discharged from a fuel cell via a hydrogen-off gas exhaust flow passage. Consumed oxygen-off gas is discharged from the fuel cell via an oxygen-off gas exhaust flow passage. The oxygen-off gas flowing through the oxygen-off gas exhaust flow passage and the hydrogen-off gas flowing through the hydrogen-off gas exhaust flow passage are mixed and diluted in a mixing portion. The gases mixed in the mixing portion flow into a combustor via a gas-liquid separator. The combustor, which includes a platinum catalyst, causes hydrogen contained in the mixed gases to react with oxygen by combustion and further reduces the concentration of hydrogen contained in the mixed gases. The mixed gases whose concentration of hydrogen has been reduced by the combustor is discharged to the atmosphere.

Abstract: Consumed hydrogen-off gas is discharged from a fuel cell via a hydrogen-off gas exhaust flow passage. Consumed oxygen-off gas is discharged from the fuel cell via an oxygen-off gas exhaust flow passage. The oxygen-off gas flowing through the oxygen-off gas exhaust flow passage and the hydrogen-off gas flowing through the hydrogen-off gas exhaust flow passage are mixed and diluted in a mixing portion. The gases mixed in the mixing portion flow into a combustor via a gas-liquid separator. The combustor, which includes a platinum catalyst, causes hydrogen contained in the mixed gases to react with oxygen by combustion and further reduces the concentration of hydrogen contained in the mixed gases. The mixed gases whose concentration of hydrogen has been reduced by the combustor is discharged to the atmosphere.