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Abstract

Disclosed is a phase-change optical recording medium which has a reflectance and a signal modulation conformed to the CD standard, and which is usable for recording at the same linear velocity as the reproducing velocity specified in the CD standard. The phase-change optical recording medium comprises a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, in which recording is performed through change from a crystalline state to an amorphous state in the recording layer. The recording layer comprises a recording material of a Ge--Te--Sb--Se system, and the recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %: Ge.gtoreq.40%, and Sb+Se.ltoreq.25% The recording medium has a reflectance of not less than 70% with respect to a light beam for reproduction when the recording layer is in one of the crystalline state and the amorphous state, and the recording medium has a reflectance of less than 40% when the recording layer is in the other state. An AuCo alloy is used as the metallic layer.

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