INFORMATION RECORDING MEDIUM

摘要

PURPOSE:To obtain an optical disk which can be selectively used for permanent recording and rewritable recording by using a recording and reproducing medium made of a metal or alloy which has at least two kinds of crystal structure in s solid state and maintains the crystal structure in one temp. region in the other temp. region. CONSTITUTION:An inter-crystal transition alloy has the crystal structure which is different in high and low temp. states. The quickly cooled crystal structure is formed by the quick cooling from the high temp. Such inter-crystal transition alloy consists preferably of an alloy composed of at least one kind of the group Ib elements of periodic table and at least one kind selected from the group IIb and Vb elements. Recording pits 6 on a disk 1 are divided to the pits for executing permanent recording and the pits for executing rewritable recording. The recording and the pits for executing rewritable recording. The recording pit 6A is the part of a recording alloy layer 9 where the reflectivity changes and the rewritable recording is executed in said part.