A multi-layer ceramic capacitor is made by alternately layering a dielectric layer constituted by a sintered body of a ceramic powder, and an internal electrode layer. The ceramic powder contains, as a main composition, barium titanate powder having a perovskite structure with a median size of 200 nm or smaller as measured by SEM observation, wherein the barium titanate powder is such that the percentage of barium titanate particle having twin defects in the barium titanate powder is less than 10% as measured by TEM observation and that its crystal lattice c/a is 1.0075 or more.

Provided is a dielectric thin film including a metal oxide. The metal oxide includes bismuth, sodium, barium, and titanium, at least a part of the metal oxide is a tetragonal crystal having a perovskite structure, and a (100) plane of at least a part of the tetragonal crystal is oriented in a normal direction of a surface of the dielectric thin film.

A solid electrolyte which contains a garnet-type composite metal oxide phase (L) and shows an excellent lithium ion conductivity is provided. The solid electrolyte contains a garnet-type composite metal oxide phase (L) and a phase (D) different from the phase (L). The phase (L) contains Li, La, Zr, O, and Ga, and an Li site in the phase (L) is substituted with the Ga. A lattice constant of the solid electrolyte is not smaller than 12.96 . The phase (D) contains at least one of LiF, BaZrO.sub.3, YF.sub.3, SrF.sub.2, and ScF.sub.3.

A ceramic body being configured of mainly BaTiO.sub.3-based crystalline particles in which a part of Ba is substituted with at least one rare earth element, wherein the ceramic body contains Ba.sub.6Ti.sub.17O.sub.40 crystalline particles of from 1.0 to 10.0% by mass.