Abstract: Provided is an alkali-niobate-based piezoelectric porcelain composition which has a crystal-structure transition point in the range of operation guarantee temperatures and which, despite this, is inhibited from abruptly changing in capacitance. The piezoelectric porcelain composition comprises Li, Na, K, Nb, Ta, Sb, and O as major constituent elements and has an alkali-niobate-based perovskite structure. When the composition has an ABO3 type perovskite structure as a unit lattice in which Z=1, the composition has a transition point at which the crystal structure changes from the monoclinic to the tetragonal system. Thus, the composition has a crystal-structure transition point at ?50° C. to 150° C. so as to utilize the high piezoelectric effect produced by the MPB at the crystal-structure transition point and, despite this, has the feature of always satisfying ?C>0.

Abstract: A solution for forming a superconductive thin film prepared by dissolving a mol of a compound selected from group A consisting of alkoxides and alkoxyalkoxides of a rare earth metal element; b mol of a compound selected from group B consisting of alkoxides and alkoxyalkoxides of Ba, Sr and Ca; and c mol of a compound selected from group C consisting of alkoxides and alkoxyalkoxides of Cu in e liter of a compound selected from group E, a solvent selected from alcohols together with d mol of a compound selected from group D for inhibiting hydrolysis action such as an amine, a ketone and a glycol, such that the following relationships:0.1.times.(a+b+c).ltoreq.d.ltoreq.3.times.(a+b+c)and0.01.ltoreq.[(a+b+c)/e].ltoreq.3can be satisfied.

Abstract: A solution for forming a superconductive thin film prepared by dissolving a mol of a compound selected from group A consisting of alkoxides and alkoxyalkoxides of a rare earth metal element; b mol of a compound selected from group B consisting of alkoxides and alkoxyalkoxides of Ba, Sr and Ca; and c mol of a compound selected from group C consisting of alkoxides and alkoxyalkoxides of Cu in e liter of a compound selected from group E, a solvent selected from alcohols together with d mol of a compound selected from group D having hydrolysis inhibitory action such as an amine, a ketone and a glycol, such that the following relationships:0.1.times.(a+b+c).gtoreq.d.gtoreq.3.times.(a+b+c)and0.1.gtoreq.[(a+b+c)/e].gtoreq.emay be satisfied.

Abstract: A composite element comprises a matrix composed of at least one member selected from the group consisting of oxides, carbides, nitrides and borides and a fibrous material made of at least one member selected from the group consisting of carbon, graphite, oxides, carbides, nitrides and borides. A plurality of composite elements are used as the electrode wall or insulating wall constituting an MHD power generating channel.