Abstract: The present invention provides an optical information recording medium having excellent characteristics in repetitive recording and a sufficient C/N ratio. The optical information recording medium includes a recording layer containing Ge, Te and Sb and a diffusion preventing layers in contact with the recording layer. A composition ratio of Ge, Te and Sb in the recording layer has numerical values which lie within the range represented by the area ABCDE in a ternary phase diagram of Ge, Te and Sb, where the points A, B, C, D and E are as follows: A (Ge50Te50), B (Ge22.5Sb22.0Te55.5), C (Ge17.0Sb41.5Te41.5), D (Ge48.0Sb26.0Te26.0), E (Ge65Te35) The diffusion layer contains at least one compound selected from an oxide, a nitride, a nitrogen oxide, a carbide and a fluoride.

Abstract: An optical information recording medium includes a recording layer that changes reversibly between a crystalline state and an amorphous state. The irradiation of the recording layer with laser beams at a predetermined wavelength changes the recording layer from one selected from the group consisting of the crystalline state and the amorphous state to the other state. The absorptance Ac of the laser beams in the recording layer when the recording layer is in the crystalline state is larger than the absorptance Aa of the laser beams in the recording layer when the recording layer is in the amorphous state. Crystallization accelerating layers for accelerating the change of the recording layer from the amorphous state to the crystalline state are formed in contact with both surfaces of the recording layer.

Abstract: An optical information recording medium is provided in which recording can be performed at higher speed with higher density by enabling the cooling power of the recording medium to be improved, the overwritten-mark distortion to be decreased, and an medium with high transmittance to be obtained. The optical information recording medium is formed by laminating, sequentially on a substrate: a protective layer; an interface layer; a recording layer whose optical characteristics are varied reversibly by irradiation of a laser beam; an interface layer; a light transmittance type reflective layer that transmits the laser beam with a wavelength &lgr;; and a thermal diffusion layer. A thickness d of the thermal diffusion layer is set to be within a range of 0<d≦({fraction (5/16)})&lgr;/n or ({fraction (7/16)})&lgr;/n≦d≦(½)&lgr;/n, wherein n indicates a refractive index of the thermal diffusion layer.

Abstract: The present invention provides an optical information medium having excellent weather resistance and repeating characteristics. The optical information medium has a barrier layer between a protective layer and a recording layer. The barrier layer includes GeN or GeON, and at least one element selected from the group consisting of Al, B, Ba, Bi, C, Ca, Ce, Cr, Dy, Eu, Ga, H, In, K, La, Mn, N, Nb, Ni, Pb, Pd, S, Si, Sb, Sn, Ta, Te, Ti, V, W, Yb, Zn and Zr.