Abstract: The mechanical strength of stabilized zirconia is improved without lowering the ion conductivity by providing a solid electrolyte comprising stabilized zirconia and a metal oxide dispersed within grains or grain boundaries of stabilized zirconia, the metal oxide having an average submicron particle size and stabilized zirconia having an average particle size larger than 1 micron, typically larger than 10 .mu.m or even 100 .mu.m.

Abstract: In the steam reforming catalyst for hydrocarbon according to the present invention, catalyst metal is supported on or in the surface layer of a zirconia carrier containing yttria and having a crystal structure primarily consisting of tetragonal system or tetragonal and cubic systems. Compared with conventional steam reforming catalyst, it has higher reaction efficiency and suppresses carbon deposition extensively even when steam/carbon ratio is low and exhibits higher hydrogen generation efficiency and higher catalyst strength. Particularly, it is suitable as a catalyst for internal reforming type fuel cell.In the steam reforming catalyst of hydrocarbon of this invention, metal catalyst can be effectively utilized by supporting metal catalyst only on surface layer of zirconia carrier.

Abstract: The present invention provides a solid electrolyte type of fuel cell of a planar type structure comprising a plurality of solid electrolyte plates, each being in the form of a flat plate and having a porous cathodic layer on one side and a porous anodic layer on the other side, which are laminated together through an interconnector plate provided in both its sides with grooves defining gas passages, wherein oxidizing agent and fuel gases are fed through said passages to the cathodic and anodic sides, thereby reducing the length of a current path running through regions of high resistance, increasing the degree of integration and improving reliability. By using heat-resistant parts for the interconnectors, cathodes and anodes, it is also possible to improve the resistance to oxidation and reduction as well as durability and obtain low resistance.