A solid ionic conducting material for use in an electrochemical device comprises an oxyhydroxide or hydrated oxide derived from of an oxide with a perovskite, Brownmillerite, layered oxide, and/or K.sub.4CdCl.sub.6 structure, the elemental composition of the initial oxide being selected to provide suitable conduction properties for the derived anhydrous or hydrated oxyhydroxide or hydrated oxide. A method of making such a solid ionic conducting material, including treatment with water, and an electrochemical device incorporating such a solid ionic conducting material (optionally as an electrolyte) are also disclosed.

A solid electrolyte layer includes a solid electrolyte and a compound represented by a composition formula M.sub.xZr.sub.2(PO.sub.4).sub.y. In the composition formula, M represents at least one selected from the group consisting of Na, K, Mg, Ca, Sr, Ba, Cu, Zn, and Ni, x satisfies 0<x2.5, and y satisfies 2.7y3.5.

Solid lithium-ion ceramic electrolyte membranes have an average thickness of less than 200 micrometers. A constituent electrolyte material has an average grain size of less than 10 micrometers. The solid lithium-ion ceramic electrolyte is free-standing. Alternatively, solid lithium-ion electrolyte membranes have a composition represented by Li.sub.1+xyM.sub.xM.sub.2xyM.sub.y(PO.sub.4).sub.3, where M is a 3.sup.+ ion, M is a 4.sup.+ ion, M is a 5.sup.+ ion, 0x2 and 0y2.

A sintered body including zirconia containing a stabilizer, wherein the sintered body has a monoclinic fraction of 0.5% or more and has a three-point bending strength of more than 1450 MPa as measured by a three-point bending test according to JIS R 1601.

A superconducting composition of matter including overlapping first and second regions. The regions comprise unit cells of a solid, the first region comprises an electrical insulator or semiconductor, and the second region comprises a metallic electrical conductor. The second region extends through the solid and a subset of said second region comprise surface metal unit cells that are adjacent to at least one unit cell from the first region. The ratio of the number of said surface metal unit cells to the total number of unit cells in the second region being at least 20 percent.