A composite wafer having an oxide single-crystal film transferred onto a support wafer, the film being a lithium tantalate or lithium niobate film, and the composite wafer being unlikely to have cracking or peeling caused in the lamination interface between the film and the support wafer. More specifically, a method of producing the composite wafer, including steps of: implanting hydrogen atom ions or molecule ions from a surface of the oxide wafer to form an ion-implanted layer inside thereof; subjecting at least one of the surface of the oxide wafer and a surface of the support wafer to surface activation treatment; bonding the surfaces together to obtain a laminate; heat-treating the laminate at 90 C. or higher at which cracking is not caused; and exposing the heat-treated laminate to visible light to split along the ion-implanted layer to obtain the composite wafer.

Disclosed is a tin oxide containing antimony and at least one element A selected from the group consisting of tantalum, tungsten, niobium, and bismuth. The antimony and the at least one element A selected from the group consisting of tantalum, tungsten, niobium, and bismuth are preferably dissolved in a solid state in tin oxide. The ratio of the number of moles of the element A to the number of moles of antimony, i.e., [(the number of moles of the element A/the number of moles of antimony)], is preferably 0.1 to 10.

To provide a structural body having a new shape and including a garnet crystal structure.

A structural body comprising Li.sub.aM.sup.1.sub.bM.sup.2.sub.cO.sub.d (5a8; 2.5b3.5; 1.5c2.5; 10d14; M.sup.1 is at least one element selected from Al, Y, La, Pr, Nd, Sm, Lu, Mg, Ca, Sr, or Ba; and M.sup.2 is at least one element selected from Zr, Hf, Nb, or Ta) including a garnet crystal structure, wherein in a scanning electron microscopic image obtained through observation of a fracture surface in a depth direction of the structural body, a striped pattern extending along the depth direction is shown, and/or in a scanning electron microscopic image obtained through observation of a cut surface in the depth direction of the structural body, a continuous body extending along the depth direction is shown.

Disclosed are a grain boundary- and surface-doped lithium-lanthanum-zirconium composite oxide solid electrolyte, a preparation method therefor, and an application thereof. Part of doping elements are step-doped at the grain boundary and the surface of the lithium-lanthanum-zirconium composite oxide solid electrolyte to improve the distribution state of the doping elements at the grain boundaries, reduce the number of grain boundaries, lower the grain boundary resistance of the lithium-lanthanum-zirconium composite oxide, thereby obtaining high ionic conductivity. The doping method has the advantages of being simple and convenient in process, low in cost and high in universality, can meet the requirements of different solid electrolytes on doping elements, and is suitable for large-scale application. The solid electrolyte obtained from the technical solution of the present application can be used in fields such as all-solid-state lithium or lithium ion batteries, semi-solid lithium ion batteries, lithium air batteries and the like.

In general, according to one embodiment, there is provided an active material. The active material contains a composite oxide having an orthorhombic crystal structure. The composite oxide is represented by a general formula of Li.sub.2+wNa.sub.2xM1.sub.yTi.sub.6zM2.sub.zO.sub.14+. In the general formula, the M1 is at least one selected from the group consisting of Cs and K; the M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al; and w is within a range of 0w4, x is within a range of 0<x<2, y is within a range of 0y<2, z is within a range of 0<z6, and is within a range of 0.50.5.

A piezoelectric composition containing: at least one or more elements selected from alkali metal elements; at least one or more elements selected from a group consisting of vanadium, niobium, and tantalum; copper or copper and germanium; and oxygen. The piezoelectric composition has a main phase, and a high Cu-concentration phase in which a content ratio of copper is higher than the main phase, and when a content ratio of oxygen in the high Cu-concentration phase is set as O.sub.g, and a content ratio of copper is set as Cu.sub.g, O.sub.g and Cu.sub.g satisfy relationships of 51O.sub.g60 and 2.0Cu.sub.g15.

The present invention aims to provide a piezoelectric composition containing a composition represented by formula (5) as the main component, wherein the composition represented by formula (5) contains a first perovskite-type oxide represented by formula (1), a second perovskite-type oxide represented by formula (2), a tungsten bronze-type oxide represented by formula (3) and a third perovskite-type oxide represented by formula (4), (K.sub.1-x-yNa.sub.xLi.sub.y).sub.q(Nb.sub.1-zTa.sub.z)O.sub.3 (1), SrZrO.sub.3 (2), Ba(Nb.sub.1-wTa.sub.w).sub.2O.sub.6 (3), (Bi.sub.0.5Na.sub.0.5)TiO.sub.3 and/or (Bi.sub.0.5K.sub.0.5)TiO.sub.3 (4), (1?m?n?p)A+mB+nC+pD (5); in formula (1), 0.20?x?0.80, 0.02?y?0.10, 0.01?z?0.30 and 0.800?q?1.050; in formula (3), 0.01?w?0.30; and in formula (5), A represents the composite oxide represented by formula (1), B represents the composite oxide represented by formula (2), C represents the composite oxide represented by formula (3), D represents the composite oxide represented by formula (4), and 0.04?m?0.07, 0?n?0.010 and 0.001?p?0.020.

[Object]

It is an object of the present invention to provide a lithium tantalate single crystal substrate which undergoes only small warpage, is free from cracks and scratches, has better temperature non-dependence characteristics and a larger electromechanical coupling coefficient than a conventional Y-cut LiTaO.sub.3 substrate.

[Means to Solve the Problems]

The lithium tantalate single crystal substrate of the present invention is a rotated Y-cut LiTaO.sub.3 single crystal substrate having a crystal orientation of 36 Y-49 Y cut characterized in that: the substrate is diffused with Li from its surface into its depth such that it has a Li concentration profile showing a difference in the Li concentration between the substrate surface and the depth of the substrate; and the substrate is treated with single polarization treatment so that the Li concentration is substantially uniform from the substrate surface to a depth which is equivalent to 5-15 times the wavelength of either a surface acoustic wave or a leaky surface acoustic wave propagating in the LiTaO.sub.3 substrate surface.

A photochemical electrode includes: an optical absorption layer; a catalyst layer for oxygen evolution reaction over the optical absorption layer; and a conducting layer over the catalyst layer. A valance band maximum of the catalyst layer is higher than a valance band maximum of the optical absorption layer. A work function of the conducting layer is larger than a work function of the catalyst layer.

A process for synthesizing a Mn.sup.4+ doped phosphor of formula I by electrolysis is presented. The process includes electrolyzing a reaction solution comprising a source of manganese, a source of M and a source of A. One aspect relates to a phosphor composition produced by the process. A lighting apparatus including the phosphor composition is also provided. A.sub.x[MF.sub.y]:Mn.sup.4+ (I) where, A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7.