Matsushita Electric Industrial Co., Ltd.

Matsushita Electronic Industrial Co., Ltd

Susumu Sanai

Noboru Yamada

Kunio Kimura

Masatoshi Takao

Eiji Ohno

Kiyoshi Kojima

Ken'chi Nagata

Norboru Yamada

Phase-change type, reversible optical information recording medium, being possible for recording, reproducing, erasing, and rewriting of information, by use of a laser beam. This invention, consists of recording thin film of ternary elements, for example, containing Ge, Te, Sb/or Bi or quaternary elements containing the fourth element of Se with which a part of Te is replaced, which is established on such surface&#x2014;flat substrates as glass or plastics. In this case, the component ratio of Te and Se is selected not to be excess for other elements, such as Ge, Sb/or Bi so as to be fixed as stable compounds of stoichiometric compositions of GeTe, SbTe/or BiTe, or GeSe, SbSe/BiSewhen crystallized. Strictly speaking, a concentration of each component is selected to have proper ratio of the number of atoms each other so as to represent whole composition as the sum of each component. By this treatment, it is possible to have high crystallization speed and long cyclability of recording/erasing. The effect of Se is to increase the viscosity of the system and to make easily to obtain amorphous state; and moreover, by selecting of proper amount diplaced with Te, it is possible to obtain the composition of recoding film superior in both characteristics of recording (amorphization) and erasing (crystallization).

Reversible optival information-recording medium

Phase-change type, reversible optical information recording medium, being possible for recording, reproducing, erasing, and rewriting of information, by use of a laser beam. This invention, consists of recording thin film of ternary elements, for example, containing Ge, Te, Sb/or Bi or quaternary elements containing the fourth element of Se with which a part of Te is replaced, which is established on such surface&mdash;flat substrates as glass or plastics. In this case, the component ratio of Te and Se is selected not to be excess for other elements, such as Ge, Sb/or Bi so as to be fixed as stable compounds of stoichiometric compositions of GeTe, Sb,Te,/or Bi,Te,, or GeSe, Sb,Se,/Bi,Se,when crystallized. Strictly speaking, a concentration of each component is selected to have proper ratio of the number of atoms each other so as to represent whole composition as the sum of each component. By this treatment, it is possible to have high crystallization speed and long cyclability of recording/erasing. The effect of Se is to increase the viscosity of the system and to make easily to obtain amorphous state; and moreover, by selecting of proper amount diplaced with Te, it is possible to obtain the composition of recoding film superior in both characteristics of recording (amorphization) and erasing (crystallization).

Reversible optical information-recording medium

A rewritable phase-change type optical information recording medium having a recording film made of a material containing Te or In as a major component and further containing B or C.

Optical information recording medium

Phase-change type, reversible optical information recording medium, being possible for recording, reproducing, erasing, and rewriting of information, by use of a laser beam. This invention consists of recording thin film of ternary elements, for example, containing Ge, Te, Sb/or Bi or quaternary elements containing the fourth element of Se with which a part of Te is replaced, which is established on such surface-flat substrates as glass or plastics. In this case, the component ratio of Te and Se is selected not to be excess for other elements, such as Ge, Sb/or Bi so as to be fixed as stable compounds of stoichiometric compositions of GeTe, Sb.sub.2 Te.sub.3 /or Bi.sub.2 Te.sub.3, or GeSe, Sb.sub.2 Se.sub.3 /Bi.sub.2 Se.sub.3 when crystallized. Strictly speaking, a concentration of each component is selected to have proper ratio of the number of atomes each other so as to represent whole composition as the sum of each component. By this treatment, it is possible to have high crystallization speed and long cyclability of recording/erasing. The effect of Se is to increase the viscosity of the system and to make easily to obtain amorphous state; and moreover, by selecting of proper amount displaced with Te, it is possible to obtain the composition of recoding film superior in both characteristics of recording (amorphization) and erasing (crystallization).

Optical information active layer mainly composed of a quaternary system of Te-Ge-Sn-Au, with composition ratios of Te, Ge and Sn that lie within an area represented by points A B C D and E on FIG. 1, with an additional amount of Au that is 1-40 atomic % of the quaternary system of Te-Ge-Sn-Au. The optical information active layer can be melted readily by a laser diode thereby achieving a high recording sensitivity, because it contains Te.sub.2 Au alloy having low melting point, CHR and erasability after repeated use and long term storage are small, and since excessive Te in the information active layer is stabilized by formings of Ge Te Su Te and Au Te.

Optical information storing medium

A permanent magnetic alloy characterized in that phosphorus of 0.6% or less by weight is added with respect to an Mn--Al--C alloy of 100% by weight comprising manganese of 68.0% to 73.0% by weight, carbon of (1/10)Mn--6.6)% to (1/3Mn--22.2)% by weight, and the remainder aluminum.

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Osaka, Japan

Susumu Sanai