Provided is a MnZnO sputtering target which can be used in DC sputtering, and a production method for the target. The MnZnO sputtering target comprises a chemical composition containing Mn, Zn, O, and at least one element X, the element X being a single one or two elements selected from the group consisting of W and Mo. The target has a relative density of 90% or more and a specific resistance of 110.sup.3 .Math.cm or less.

Provided is an optical recording medium including two or more recording layers, and a light irradiation surface that is irradiated with light for recording an information signal on the two or more recording layers. Among the two or more recording layers, at least one layer other than a layer located on the deepest side from the light irradiation surface includes an oxide of a metal A, an oxide of a metal B, and an oxide of a metal C. The metal A is at least one kind among W, Mo, and Zr, the metal B is Mn, and the metal C is at least one kind among Cu, Ag, and Ni. Ratios of the metal A, the metal B, and the metal C satisfy a relationship of 0.46x1 (provided that, x1=a/(b+0.8c), a representing an atomic ratio [atom %] of the metal A with respect to the sum of the metal A, the metal B, and the metal C, b representing an atomic ratio [atom %] of the metal B with respect to the sum of the metal A, the metal B, and the metal C, and c representing an atomic ratio [atom %] of the metal C with respect to the sum of the metal A, the metal B, and the metal C.

An information recording medium includes three or more information layers. The three or more information layers include a first information layer including a first dielectric film, a recording film, and a second dielectric film in this order. The first dielectric film contains an oxide of D1. The D1 represents at least one element selected from a first group consisting of Nb, Mo, Ta, W, Ti, Bi, and Ce. The recording film contains at least W, Cu, Mn, and oxygen and M. The M represents at least one element selected from a second group consisting of Nb, Mo, Ta, and Ti. The W, the Cu, the Mn, and the M except the oxygen in the recording film satisfy a following formula (1):

W.sub.xCu.sub.yMn.sub.zM.sub.100-x-y-z (atom %)(1) wherein x, y, and z satisfy 15x60, yz, 0<z40, and 60x+y+z98.

An information recording medium according to the present disclosure is an information recording medium of a write-once-read-many type and records or reproduces information when irradiated with laser light. The information recording medium includes: a substrate; a plurality of information layers at least one information layer of which includes a recording film that is a WO-based recording film comprising at least tungsten (W) and oxygen (O); and a dielectric film A in contact with the WO-based recording film, the dielectric film A comprising at least 30 mol % tin oxide.

Provided is an optical recording medium including two or more recording layers, and a light irradiation surface that is irradiated with light for recording an information signal on the two or more recording layers. Among the two or more recording layers, at least one layer other than a layer located on the deepest side from the light irradiation surface includes an oxide of a metal A, an oxide of a metal B, and an oxide of a metal C. The metal A is at least one kind among W, Mo, and Zr, the metal B is Mn, and the metal C is at least one kind among Cu, Ag, and Ni. Ratios of the metal A, the metal B, and the metal C satisfy a relationship of 0.46x1 (provided that, x1=a/(b+0.8c), a representing an atomic ratio [atom %] of the metal A with respect to the sum of the metal A, the metal B, and the metal C, b representing an atomic ratio [atom %] of the metal B with respect to the sum of the metal A, the metal B, and the metal C, and c representing an atomic ratio [atom %] of the metal C with respect to the sum of the metal A, the metal B, and the metal C.

An optical recording medium includes a light-receiving surface that receives incident light and at least three information signal layers on which information signals are to be optically recorded. Among the at least three information signal layers, the information signal layer closest to the light-receiving surface has a reflectance in a range of 4% to 11%.

An optical recording medium includes a plurality of information signal layers on which information signals are to be optically recorded. Among the plurality of information signal layers, the information signal layer closest to the light-receiving surface has a reflectance of more than 4%.

An optical recording medium includes a plurality of information signal layers on which information signals are to be optically recorded. Among the plurality of information signal layers, the information signal layer closest to the light-receiving surface has a reflectance of more than 4%.

Provided is a MnZnO sputtering target which can be used in DC sputtering, and a production method for the target. The MnZnO sputtering target comprises a chemical composition containing Mn, Zn, O, and at least one element X, the element X being a single one or two elements selected from the group consisting of W and Mo. The target has a relative density of 90% or more and a specific resistance of 110.sup.3 .Math.cm or less.

The present invention relates to an information storage medium and a method for long-term storage of information comprising the steps of: providing a ceramic substrate; coating the ceramic substrate with a layer of a second material different from the material of the ceramic substrate, the layer having a thickness no greater than 10 m; tempering the coated ceramic substrate to form a writable plate or disc; encoding information on the writable plate or disc by using a laser and/or a focused particle beam to manipulate localized areas of the writable plate or disc.