Abstract: An optical hydrogen gas detecting membrane is prepared by sequentially depositing a platinum oxide layer and a catalytic metal layer on a transparent substrate, such as quartz glass, by vapor deposition such as the sputtering method. Palladium or platinum is used as the catalytic metal layer.

Abstract: A hydrogen gas detecting material, which changes in light absorption characteristics when exposed to an atmosphere containing hydrogen, and the coating method are characterized in that (1) the principal component of the hydrogen gas detecting material is tungsten oxide, (2) palladium is deposited on the surface of the tungsten oxide, (3) the tungsten oxide is coated on a substrate by a sputtering method involving a controlled oxygen pressure, and (4) the temperature of the substrate during coating with the tungsten oxide is room temperature (20° C.).

Abstract: A hydrogen gas detecting material, which changes in light absorption characteristics when exposed to an atmosphere containing hydrogen, and the coating method are characterized in that (1) the principal component of the hydrogen gas detecting material is tungsten oxide, (2) palladium is deposited on the surface of the tungsten oxide, (3) the tungsten oxide is coated on a substrate by a sputtering method involving a controlled oxygen pressure, and (4) the temperature of the substrate during coating with the tungsten oxide is room temperature (20° C.).

Abstract: An optical hydrogen gas detecting membrane is prepared by sequentially depositing a platinum oxide layer and a catalytic metal layer on a transparent substrate, such as quartz glass, by vapor deposition such as the sputtering method. Palladium or platinum is used as the catalytic metal layer.

Abstract: Piezoelectric ceramics are provided consisting of a ternary system composition of PbTiO.sub.3 -PbZrO.sub.3 -La(Mn.sub.1-4.alpha. Ni.sub.3.alpha. W.sub..alpha.)O.sub.3 where .alpha. is in the range of 3/40.ltoreq..alpha..ltoreq.1/4.

Abstract: A trapped energy type of piezoelectric filter includes a polarized ceramic wafer 9, input and output electrodes 11, 13 secured to one major surface of the wafer and spaced from each other by a constant width gap, and a ground electrode 15 secured to the opposite major surface underlying the input and output electrodes. The configuration of the ground electrode is made symmetrically concave or convex about its longitudinal axis in varying degrees to thereby control the band pass width, the symmetry of the filter characteristic about a center frequency, and eliminate peak ripples.