Abstract: An optical recording medium contains a recording layer being composed of a phase-change recording material where at least four elements, Ga, Sb, Sn and Ge are contained and the transfer linear velocity is 20 m/s to 30 m/s, and when the wavelength of a recording/reproducing light is within the range of 650 nm to 665 nm and the recording linear velocity is 20 m/s to 28 m/s, the refractive index Nc and the extinction coefficient Kc in a crystalline state and the refractive index Na and the extinction coefficient Ka in an amorphous state in the recording layer respectively satisfy the following numerical expressions: 2.0?Nc?3.0, 4.0?Kc?5.0, 4.0?Na?5.0, and 2.5?Ka?3.1, and information is recordable at the range of 20 m/s to 28 m/s of recording linear velocity.

Abstract: An optical recording medium including a transparent substrate; and at least one multi-layer information layer located on the transparent substrate and including a phase change recording layer configured to record information by changing its phase between a crystallization state and an amorphous state, a protective layer, and a reflection layer, wherein the average of partial response signal-to-noise ratio (PRSNR) in all data regions of the recording medium is not less than 15.0 after one direct overwriting (DOW1) cycle and the standard deviation of inter-track distribution of PRSNR is not greater than 0.3.

Abstract: An optical recording medium including: a substrate having translucency; a first protective layer thereon; a recording layer composed of a phase-change material; a second protective layer; and a reflective layer, wherein laser beam irradiation causes phase-change of the recording layer between a crystalline phase and an amorphous phase thereby at least one of to rewrite and to record information, wherein the phase-change material comprises Ga, Sb and Sn, Ga content, Sb content, and Sn content satisfy the following formula, and the total content of Ga, Sb and Sn is at least 80 atomic % of the entire phase-change material: Ga?Sb?Sn? (where, ?+?+?=100 atomic %), where 20??2.75?+0.708?+1.18??7.56?43, and ?/(?+?)?0.12.

Abstract: To provide an optical recording medium which can maintain excellent recording characteristics and storage reliability even at high recording speeds of 3× to 10× on DVD, particularly at 8× or faster, and whose recording material can be readily initialized to provide a uniform reflectivity distribution. The optical recording medium includes a substrate, first protective layer, recording layer, second protective layer and reflective layer, the first protective layer, recording layer, second protective layer and reflective layer being disposed on the substrate in this order or in reverse order, wherein the recording layer comprises a composition expressed by the Formula (X1)?Sb?(X2)? where X1 represents at least one element selected from Ga, Ge and In; X2 represents at least one element selected from Au, Ag and Cu; and ?, ? and ? represent atomic % of their respective elements (where 2???20, 55???95, 0<??10, and (?+?+?)=100).

Abstract: An object of the present invention is to provide an optical recording medium for high speed recording corresponding to 3× speed to 10× speed (10 m/s to 36 m/s) of DVD with a favorable recording sensitivity and overwriting performance (or characteristic). Therefore, the optical recording medium is characterized by providing on the transparent substrate at least a first protective layer, a phase-change recording layer having a maximum recording linear velocity of 10.0 m/s or more and is capable of being recorded at least at any one linear velocity of 10.0 m/s to 36.0 m/s, a second protective layer, a reflective layer having a thermal conductivity of 300 W/m·K or more and a layer of a low thermal conductivity material having a thermal conductivity of 7 W/m·K or less disposed between the second protective layer and the reflective layer with a thickness of 0.5 nm or more and 8.0 nm or less.