There are provided a lithium-containing garnet crystal high in density and ionic conductivity, and an all-solid-state lithium ion secondary battery using the lithium-containing garnet crystal. The lithium-containing garnet crystal has a chemical composition represented by Li.sub.7-xLa.sub.3Zr.sub.2-xTa.sub.xO.sub.12 (0.2≦x≦1), and has a relative density of 99% or higher, belongs to a cubic system, and has a garnet-related structure. The lithium-containing garnet crystal has a lithium ion conductivity of 1.0×10.sup.−3 S/cm or higher. Further, this solid electrolyte material has a lattice constant a of 1.28 nm≦a≦1.30 nm, and lithium ions occupy 96h-sites in the crystal structure. The all-solid-state lithium ion secondary battery has a positive electrode, a negative electrode and a solid electrolyte, and the solid electrolyte is constituted of the lithium-containing garnet crystal according to the present invention.

A bismuth and magnesium co-doped lithium niobate crystal includes Li.sub.2CO.sub.3, Nb.sub.2O.sub.5, Bi.sub.2O.sub.3 and MgO, wherein the molar ratio of [Li] and [Nb] is 0.90-1.00, the molar percentage of Bi.sub.2O.sub.3 in the mixture is 0.25-0.80%, and the molar percentage of MgO in the mixture is 3.0-7.0%. The bismuth and magnesium co-doped lithium niobate crystal has enhanced photorefraction, improved photorefractive sensitivity, shortened holographic grating saturation writing time, and the photorefractive diffraction efficiency can reach up to 17%. The response time is only 170 ms, when the holographic storage experiment is carried out using 488 nm continuous laser. Therefore, this crystal can be used in the field of holographic imaging.

A bismuth and magnesium co-doped lithium niobate crystal includes Li.sub.2CO.sub.3, Nb.sub.2O.sub.5, Bi.sub.2O.sub.3 and MgO, wherein the molar ratio of [Li] and [Nb] is 0.90-1.00, the molar percentage of Bi.sub.2O.sub.3 in the mixture is 0.25-0.80%, and the molar percentage of MgO in the mixture is 3.0-7.0%. The bismuth and magnesium co-doped lithium niobate crystal has enhanced photorefraction, improved photorefractive sensitivity, shortened holographic grating saturation writing time, and the photorefractive diffraction efficiency can reach up to 17%. The response time is only 170 ms, when the holographic storage experiment is carried out using 488 nm continuous laser. Therefore, this crystal can be used in the field of holographic imaging.

The disclosed optical lens assemblies may include a deformable optical element including a substantially transparent transducer configured to deform, and thus change at least one optical property of, the deformable optical element. At least a portion of the substantially transparent transducer may be positioned within a substantially transparent optical aperture of the optical lens assembly. Various head-mounted displays incorporating such an optical lens assembly, and methods of fabricating the same, are also disclosed.

The disclosed optical lens assemblies may include a deformable optical element including a substantially transparent transducer configured to deform, and thus change at least one optical property of, the deformable optical element. At least a portion of the substantially transparent transducer may be positioned within a substantially transparent optical aperture of the optical lens assembly. Various head-mounted displays incorporating such an optical lens assembly, and methods of fabricating the same, are also disclosed.

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.

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.

An elastic wave device includes a piezoelectric substrate, an IDT electrode including a first electrode layer located on the piezoelectric substrate and including one of Mo and W as a main component and a second electrode layer laminated on the first electrode layer and including Cu as a main component, and a dielectric film located on the piezoelectric substrate and covering the IDT electrode. The piezoelectric substrate is made of lithium niobate. The dielectric film is made of silicon oxide. The elastic wave device utilizes Rayleigh waves propagating along the piezoelectric substrate.

An elastic wave device includes a piezoelectric substrate, an IDT electrode including a first electrode layer located on the piezoelectric substrate and including one of Mo and W as a main component and a second electrode layer laminated on the first electrode layer and including Cu as a main component, and a dielectric film located on the piezoelectric substrate and covering the IDT electrode. The piezoelectric substrate is made of lithium niobate. The dielectric film is made of silicon oxide. The elastic wave device utilizes Rayleigh waves propagating along the piezoelectric substrate.

A processed wafer includes an outer surface, and a treated portion having a depth of 0 to 50 μm measured from the outer surface. At least a part of the treated portion has an oxygen concentration of less than 13 wt %. A method for processing a wafer includes the steps of: applying a reducing medium on the wafer, the reducing medium is in powder form and including a reducing agent, and at least one of a catalyst and a releasing agent; subjecting the wafer to a reduction reaction at a temperature below Curie temperature of the and under a non-oxidizing atmosphere so as to obtain the aforesaid processed wafer.