A metal oxide film includes indium, M, (M is Al, Ga, Y, or Sn), and zinc and includes a region where a peak having a diffraction intensity derived from a crystal structure is observed by X-ray diffraction in the direction perpendicular to the film surface. Moreover, a plurality of crystal parts is observed in a transmission electron microscope image in the direction perpendicular to the film surface. The proportion of a region other than the crystal parts is higher than or equal to 20% and lower than or equal to 60%.

A method for producing an oriented AlN sintered body includes a first step of preparing a formed body by forming a mixture obtained by mixing a sintering aid with an AlN raw-material powder containing a plate-like AlN powder whose plate surface is a c-plane and which has an aspect ratio of 3 or more and an average thickness of 0.05 to 1.8 m, wherein the mixture is formed such that the plate surface of the plate-like AlN powder is disposed along a surface of the formed body; and a second step of obtaining an oriented AlN sintered body by subjecting the formed body to hot-press sintering in a non-oxidizing atmosphere while applying a pressure to the surface of the formed body.

A metal oxide film includes indium, M, (M is Al, Ga, Y, or Sn), and zinc and includes a region where a peak having a diffraction intensity derived from a crystal structure is observed by X-ray diffraction in the direction perpendicular to the film surface. Moreover, a plurality of crystal parts is observed in a transmission electron microscope image in the direction perpendicular to the film surface. The proportion of a region other than the crystal parts is higher than or equal to 20% and lower than or equal to 60%.

An aluminum nitride plate satisfies both of a relation 1: c1>97.5% and a relation 2: c2/c1<0.995 where c1 is a c-plane degree of orientation that is defined as a ratio of a diffraction intensity of (002) plane to a sum of the diffraction intensity of (002) plane and a diffraction intensity of (100) plane when the surface layer of the aluminum nitride plate is subjected to an X-ray diffraction measurement, and c2 is a c-plane degree of (002) plane to the sum of the diffraction intensity of (002) plane and the diffraction intensity of (100) plane when a portion other than the surface layer of the aluminum nitride plate is subjected to the X-ray diffraction. Moreover, in the aluminum nitride plate, a difference in nitrogen content between the surface layer and the portion other than the surface layer is less than 0.15% in weight ratio.

According to one embodiment, a solid electrolyte includes a sintered body of ceramic grains. The sintered body includes a crystal plane having an ion conducting path. The crystal plane is oriented in a direction which intersects at least one surface of the solid electrolyte.

There is provided a piezoelectric laminate, including: a substrate; a base layer formed on the substrate; and a piezoelectric film containing alkali niobium oxide and having a perovskite structure, which is formed on the base layer, as a polycrystalline film, and represented by a composition formula of (K.sub.1-xNa.sub.x)NbO.sub.3 (0<x<1), wherein a crystal grain group forming the piezoelectric film includes a crystal grain having a ratio of 0.01 nm.sup.1 or more and 0.1 nm.sup.1 or less, which is the ratio of an outer peripheral length to a cross-sectional area when observing a cross-section of the crystal grain.

An aluminum nitride plate satisfies a c1>97.5%, a c2>97.0%, a w1<2.5 degrees, and a w1/w2<0.995 where c1 is a c-plane degree of orientation that is defined as a ratio of a diffraction intensity of (002) plane when a surface layer of the aluminum nitride plate is subjected to an X-ray diffraction measurement, and c2 is a c-plane degree of orientation that is defined as a ratio of the diffraction intensity of (002) plane when a portion other than the surface layer of the aluminum nitride plate is subjected to the X-ray diffraction measurement, wherein w1 is a half-value width in an X-ray rocking curve profile of (102) plane of the surface layer and w2 is a half-value width in the X-ray rocking curve profile of (102) plane of the portion other than the surface layer.

An oriented apatite-type oxide ion conductor includes a composite oxide expressed as A.sub.9.33+x[T.sub.6.00yM.sub.y]O.sub.26.0+z, where A represents one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Be, Mg, Ca, Sr, and Ba, T represents an element including Si or Ge or both, and M represents one or two or more elements selected from the group consisting of B, Ge, Zn, Sn, W, and Mo, and where x is from 1.00 to 1.00, y is from 0.40 to less than 1.00, and z is from 3.00 to 2.00.

An electroactive ceramic may be incorporated into a transparent optical element between transparent electrodes and may characterized by a preferred crystallographic orientation. The preferred crystallographic orientation may be aligned along a polar axis of the electroactive ceramic and substantially parallel to each of the electrodes. Optical properties of the optical element, including transmissivity, haze, and clarity may be substantially unchanged during actuation thereof and the attendant application of a voltage to the electroactive ceramic.

According to one embodiment, a solid electrolyte includes a sintered body of ceramic grains. The sintered body includes a crystal plane having an ion conducting path. The crystal plane is oriented in a direction which intersects at least one surface of the solid electrolyte.