JP2002092938A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase change type optical recording medium useful for a large number of times of repetitive recording. SOLUTION: The material of a recording layer consists of Sb, Te and an element whose covalent bond radius is 1.5 to 1.7, and the dissociation energy for Sb or Te is 70 to 95 kcalmol-1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change type optical recording medium for recording / reproducing information by changing the optical constant of a recording material by irradiating an electromagnetic wave, particularly a semiconductor laser beam.

[0002]

2. Description of the Related Art A phase-change optical recording medium is one of optical recording media capable of recording, reproducing and erasing information by irradiating a laser beam. GeTe, GeTeSe, GeSb may be used as a recording layer material in this phase change type optical recording medium.
Te, GeSbTeSe and the like are well known. Also,
AgInSbTe with high sensitivity and good erasing characteristics has been proposed as a new recording layer material (JP-A-2-37466).
JP, JP-A-2-171325, JP-A-2-4
No. 15581, JP-A-4-141485). Further, as a recording layer material containing Sb and Te as main components, Ag, Ge, In, Pd, Si, and the like are added thereto to improve the stability of the recording film and the easiness of initial crystallization. Japanese Unexamined Patent Publication No. Hei.
No. 1316) has also been proposed.

Since such a phase-change type optical recording medium is recorded in a heat mode, deterioration due to repeated recording / erasing is generally recognized many times, and improvement of the repetition characteristics is a major problem. In order to solve such a problem, Japanese Patent Application Laid-Open Nos. 4-61383 and 8-2875.
Japanese Patent Publication No. 15 proposes to add nitrogen or the like to the recording layer. In JP-A-8-287515, a heat-resistant protective layer is provided above and below a recording layer, and a third heat-resistant protective layer is provided on an upper heat-resistant protective layer. It has been proposed to reduce the thermal expansion coefficient of the other two heat-resistant protective layers to prevent deformation, reduce mass transfer, and improve the repetition characteristics. In an optical recording medium for DVD, a high linear velocity is indispensable due to a large capacity. Therefore, it is necessary to increase a crystallization speed and to prevent deterioration due to crystallization of a recording mark which may appear as a side effect. is there.

[0004]

However, the addition of an element such as nitrogen described above is effective in improving the repetition characteristics, but is not suitable for high linear velocities because the crystallization speed is reduced. The object of the present invention has been made in view of such a situation, and is not degraded even after a large number of repetitions, is compatible with high linear velocities, and has good recording mark preservability. An object of the present invention is to provide a changeable optical recording medium.

[0005]

According to the present invention, first, there is provided an optical recording medium having a recording layer containing Sb and Te as main components, wherein the recording layer further has a covalent bond radius of 1.5 °.
And 1.7 ° and the dissociation energy for Sb or Te is 70 kcalmol ^-1 to 95 kcal.
An optical recording medium characterized by adding at least one element present between mol ^{−1 and 1} is provided.

Second, in the optical recording medium according to the first aspect, the additive element is La, Ce, Pr, Gd, Tb, or Lu.
An optical recording medium characterized by being at least one element selected from the group consisting of:

Third, when the element described in the first or second optical recording medium is A, the composition (atm%) in the formula of SbαTeβAγ representing the composition of the recording layer material is 60 ≦ An optical recording medium is provided, wherein α ≦ 80, 20 ≦ β ≦ 35, and 0 <γ ≦ 15 (where α + β + γ = 100).

Fourth, an optical recording medium having a recording layer containing Sb and Te as main components, wherein the recording layer further has at least one kind of covalent bond radius between 1.4 ° and 2.0 °. An optical recording medium is provided, wherein an element and at least one element having a dissociation energy for Sb or Te between 45 kcalmol ^-1 and 110 kcalmol ^-1 are added.

Fifthly, in the optical recording medium according to the fourth aspect, at least one element having a covalent bond radius between 1.4 ° and 2.0 ° is Ca, Sr, Y, In, Ba,
Hf, Dy, Sm, Zr, Ho, Pb, Eu, Bi, G
selected from d, Tb, Sc, Sn, Yb and Na;
Or the dissociation energy for Te is 45 kcalmol
^At least one element between ^-1 and 110 kcalmol ^-1 is Ag, Au, Cu, Ga, Al, Ge, S
i, B, N, P, As, Cl, F, Br, I, Ti, S
An optical recording medium is provided, which is selected from e, S, H, Tb, and Gd.

Sixth, in the optical recording medium according to the fourth or fifth aspect, the covalent radius is from 1.4 ° to 2.0 °.
Has a dissociation energy with respect to X, Sb or Te of 45 kcalmol ^-1 to 11
When at least one element between ⁰ kcalmol ^-1 is Y, it represents the composition of the recording layer material. SbαTeβ
In the formula of XγYδ, the composition (atm%) is 55
≦ α ≦ 80, 20 ≦ β ≦ 35, 0 <γ <10, 0 <δ ≦
10 (where α + β + γ + δ = 100) is provided.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As described above, in one of the optical recording media of the present invention, the recording layer material is mainly composed of Sb and Te, the covalent radius of which is between 1.5 ° and 1.7 °, and the dissociation energy is 70 kcalmol. ^-1 to 95 kcalmol ^-1 , preferably La, Ce, Pr, Gd, T
It is obtained by adding at least one element selected from b and Lu.

The crystallization rate tends to increase as the covalent radius of the additional element increases. Therefore, the crystallization speed can be controlled by selecting the size of the covalent radius of the additional element. However, when the crystallization speed is increased, crystallization is extremely apt to proceed depending on the added element, and the recording mark may be lost during long-term storage or under high temperature and high humidity. In order to prevent this, it is necessary to add an element which is difficult to crystallize even under high temperature and high humidity, despite the large covalent bond radius and high crystallization speed. For this purpose, an element having a large dissociation energy with respect to Sb or Te as a main component of the additive element is considered to be effective.

Therefore, in the present invention, La, Ce, Pr, Gd, Td are considered to simultaneously satisfy the seemingly contradictory characteristics of high-speed crystallization necessary for high linear velocity and improvement of storage characteristics.
b, at least one element selected from Lu is added. Since these elements have a covalent bond radius between 1.5 ° and 1.7 °, the addition of these elements promotes the formation of crystal nuclei and enables high-speed crystallization. Also, Sb
Or the dissociation energy for Te is 70 kcalmol
^Since it is between ^-1 and 95 kcalmol ^-1 , the crystallization temperature is increased, so that the recording marks do not disappear even when stored under high temperature and high humidity.

Table 1 below shows the covalent bond radius (Å) and dissociation energy of each element.

[Table 1] Here, the covalent radius is the data book "Physical Properties of Elements" published by Japan-Soviet News Agency, supervised by Ge We Samsonov.
The data by polling in Chapter 1, P-33, was cited. The dissociation energy is calculated using the CRC Hand book of Chemistr
y and Physics ”9-86.

That is, La, Ce, Pr, Gd, Tb, L
u represents at least one element selected from these elements as Sb
By adding to the -Te alloy, it is possible to raise the crystallization temperature for improving the storage characteristics at the same time as high-speed crystallization capable of supporting a high linear velocity. The specific linear velocity at this time is 6 m /
s to 9 m / s, and the crystallization temperature can be controlled between 165 ° C. and 185 ° C. by the above-mentioned elements and the added amount thereof.

On the other hand, in order to further improve the characteristics of the present invention, as a result of study based on the idea of function separation,
A recording layer material containing Sb and Te as main components has at least one kind of element having a covalent bond radius of 1.4 ° to 2.0 ° and a dissociation energy for Sb or Te of 45 kc.
By adding at least one kind of element between almol ^-1 and 110 kcalmol ^-1 , it has become possible to realize a further increase in speed, an improvement in storage characteristics, and an improvement in repetition characteristics and recording sensitivity. That is, since the functions of the elements are separated and the group of added elements is expanded to be added to the Sb-Te alloy, it is possible to add an element having a large covalent bond radius and to increase the range of dissociation energy.

Here, the covalent bond radius ranges from 1.4 ° to 2.
0 °, and the selected elements are Ca, S
r, Y, In, Ba, Hf, Dy, Zr, Ho, Pb,
Eu, Bi, Gd, Tb, Sm, Sc, Sn, Yb, N
a, whereby the corresponding linear velocity is 4.5 m / s
From 12.0 m / s to 12.0 m / s. Tables 2 and 3 below show the covalent bond radii of these elements.

[0018]

[Table 2]

[0019]

[Table 3]

Regarding the dissociation energy, Sb or Te
Is 45 kcalm.
ol ^-1 to 110 kcalmol ^-1 . The elements contained therein are Ag, A
u, Cu, Ga, Al, Ge, Si, B, N, P, A
s, Cl, F, Br, I, Ti, S, H, Tb, and Gd. At least one of the elements has a covalent radius between 1.4 ° and 2.0 °. Added to the Sb-Te alloy together with at least one element,
As a result, the corresponding linear velocity can be widened from 4.5 m / s to 12.0 m / s as described above, and the crystallization temperature for improving the storage characteristics can be widened from 150 ° C. to 220 ° C. The dissociation energies of the elements used here are shown below.

[0021]

[Table 4]

[0022]

[Table 5]

Since these additional elements change the bonding strength depending on the magnitude of the dissociation energy, when the energy exceeds 70 kcalmol ^-1 , the repetition characteristics are improved. Although the cause is unknown, it is considered that since the bonding strength between the elements is large, the composition change and the structural change are small even in the repetition of melting and solidification by irradiating a laser beam for each recording.

Further, Ge, S, and Sb-Te alloys
It is considered that i, O, S, Ci, F, Br, I, etc. function as acceptors and donors, so that the light absorption efficiency is improved and the recording sensitivity is improved.

Of the additional elements, Tb and Gd are useful both as an element for expanding the covalent bond radius and as an element for expanding the range of the dissociation energy. It is desirable to combine with elements selected from the listed elements.

The amount of the additional element is determined by La,
In the case of Ce, Pr, Gd, Tb, and Lu, when the composition formula when these elements are A is SbαTeβAγ, the composition (atm%) of each element is 60 ≦ α ≦ 80 and 20 ≦ β ≦ 35. , 0 <γ ≦ 15 (where α + β + γ = 100), it is possible to cope with a high linear velocity, and the storage characteristics are repeatedly improved. Particularly preferred ranges are 68 ≦ α ≦ 75, 25 ≦ β ≦ 30, 2 ≦ γ ≦ 7 (where α + β + γ = 100).

In another example of the present invention (in the case of a function-separated type), the amount of the added element is such that the covalent bond radius is 1.
Ca, Sr, Y, In, B between 4% and 2.0%
a, Hf, Dy, Zr, He, Pb, Eu, Bi, G
At least one element selected from d, Tb, Sm, Sc, Sn, Yb, and Na is X, and the dissociation energy is between 45 kcalmol ^-1 and 110 kcalmol ^-1 . Ag, Au, Cu, Ga, Al, Ge, Si,
B, N, P, As, Cl, F, Br, I, Ti, S,
Assuming that the composition formula when at least one element selected from the elements of H, Tb, and Gd is Y is SbαTeβXγYδ, the composition (atm%) of each element is 55 ≦ α ≦ 80, 20 ≦ β ≦ 35, When 0 <γ ≦ 10, 0 <δ ≦ 10 (where α + β + γ = 100), high-speed operation is possible, and storage characteristics, repetition characteristics, and recording sensitivity are improved. Particularly preferred ranges are 65 ≦ α ≦ 72, 25 ≦ β ≦ 30, 1 ≦ γ ≦ 6, and 1 <δ ≦ 7. Particularly in the case of the above Y, it is more effective to add two kinds of elements. In this case, there are substantially three types of additive elements.

Next, the configuration of the present invention will be specifically described with reference to the drawings. FIG. 1 shows an example of the structure of a phase-change optical recording medium according to the present invention. A lower heat-resistant protective layer 2, a recording layer 3, an upper heat-resistant protective layer 4, and a reflective heat radiation layer 5 are formed on a substrate 1 having a guide groove. Are sequentially provided.

The material of the substrate 1 is usually glass, ceramics, or resin, and a resin substrate is preferable in terms of moldability. Representative examples include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, polyethylene resin, polypropylene resin, silicone resin, fluororesin, ABS resin, urethane resin, and the like. Resins are preferred. Further, the shape of the substrate may be a disk shape, a card shape or a sheet shape.

The heat-resistant protective layers 2 and 4 can be formed by various vapor phase growth methods, for example, a vacuum evaporation method, a sputtering method, an electron beam method, and the like. Further, the thickness of the lower heat-resistant protective layer is preferably 500 to 3000, preferably 800 to 2000, although it depends on its function, that is, the function as a heat-resistant layer and a multiple interference layer. Further, the upper heat-resistant protective layer has a thickness of 100 to 1000 °, preferably 150 to 350 °.
Å is good.

For the recording layer 3, various vapor phase epitaxy methods can be used as in the case of the heat-resistant protective layer. Although the thickness of the recording layer varies depending on the band gap of the recording layer material in order to effectively use the multiple interference, the band gap is 1.0 e.
50 to 500 °, preferably 100 to 2
50 ° is good. That is, when the band gap is 1.0 eV or less, the absorption increases, so that it is necessary to reduce the film thickness to increase the transmitted light.

Various metals and alloys can be used for the reflective heat radiation layer 5, and in particular, Al-Ti, Al-Ni, Al-Mn,
Al alloys such as Al-Cr, Al-Zr, Al-Si and A
An Ag alloy such as g-Pd is desirable. These layers are formed by a vacuum deposition method, a sputtering method, an electron beam method, or the like, and have a thickness of 200 to 3000 °, preferably 500
~ 2000Å is good.

[0033]

The present invention will be described more specifically with reference to the following examples.

(Example 1) Pitch: 0.72 μm, depth: 4
A lower heat-resistant protective layer, a recording layer, an upper heat-resistant protective layer, and a reflective heat-dissipating layer were sequentially laminated by a sputtering method on a polycarbonate substrate having a groove thickness of 0.6 mm, a thickness of 0.6 mm, and a diameter of 120 mmφ according to the configuration shown in Table 6 below. An optical recording medium was created. Here, ZnS, SiO ₂ was used for the heat-resistant protective layer.
Sb ₆₈ Te ₂₅ La ₇ was used as a recording layer material, and an Al alloy was used as a reflective layer material.

[0035]

[Table 6] The optical recording medium thus obtained was initialized with a high-power semiconductor laser, and the disk characteristics were evaluated.

The evaluation items were as follows: recording linear velocities of 4.0 m / s, 6.0 m / s, 8.0 m / s, 1
0.0 m / s and 12.0 m / s. The recording signal at this time is an EFM random pattern, and the recording / reproducing linear velocity is 3.5 m / s. The measured mark jitter value is 3T
It is a signal and is converted to% display. The repetition characteristic is evaluated by a jitter value at a recording linear velocity of 8.0 m / s. As for the storage characteristics, the recording characteristics after storage at high temperature and high humidity of 80 ° C. and 85% RH for 300 hours were evaluated by a jitter value at a recording linear velocity of 80 m / s. The recording power is fixed at 10 mw. Further, when forming a recording film, crystallization temperature measurement data was prepared, and the crystallization temperature was measured with a differential scanning calorimeter.

Example 2 Sb ₆₈ Te ₂₅ G was used as a recording layer material.
The optical-recording medium except for using the d ₇ is in the same manner as in Example 1.

Example 3 Sb ₆₈ Te ₂₅ L was used for the recording layer material.
The optical-recording medium except for using the u ₇ is in the same manner as in Example 1.

Example 4 Sb ₆₈ Te ₂₄ B was used for the recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that a ₃ Si ₅ was used.

Example 5 Sb ₆₈ Te ₂₄ G was used as a recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that e ₄ Gd ₄ was used.

Example 6 Sb ₆₈ Te ₂₄ I was used as a recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that n ₄ B ₄ was used.

Example 7 Sb ₆₈ Te ₂₄ T was used for the recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that b ₂ In ₃ Ge ₃ was used.

Example 8 Sb ₆₈ Te ₂₄ P was used as a recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that b ₃ Ge ₃ Gd ₂ was used.

Example 9 Sb ₆₈ Te ₂₄ B was used as a recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that i ₃ P ₂ Ag ₃ was used.

Example 10 Sb ₆₈ Te ₂₄ was used as a recording layer material.
An optical recording medium was prepared in exactly the same manner as in Example 1 except that Ca ₃ Cl ₃ Au ₂ was used.

Comparative Example 1 An optical recording medium was prepared in exactly the same manner as in Example 1 except that Sb ₇₅ Te ₂₅ was used as a recording layer material.

(Comparative Example 2) Sb ₆₈ Te ₂₇ G was used for the recording layer material.
except for using the e ₅ is to produce an optical recording medium in the same manner as in Example.

The crystallization temperatures of the optical recording media of Examples 1 to 10 are shown in Table 7, the disk characteristics are shown in Tables 8 to 17, and the disk characteristics of Comparative Examples 1 and 2 are shown in Tables 18 to 19.
Shown in

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

[Table 9]

[0052]

[Table 10]

[0053]

[Table 11]

[0054]

[Table 12]

[0055]

[Table 13]

[0056]

[Table 14]

[0057]

[Table 15]

[0058]

[Table 16]

[0059]

[Table 17]

[0060]

[Table 18]

[0061]

[Table 19]

From the results of the above examples, it was found that Sb and T
e as the main component, to which La has a covalent bond radius of 1.69 ° and a dissociation energy of 91 kcalmol ⁻¹ , and also has a covalent bond radius of 1.62 ° and a dissociation energy of 82 kc
Gd of almol ^-1 and covalent radius of 1.56１．５
In the optical recording medium having a recording layer material to which Lu having a dissociation energy of 78 kcalmol ^-1 is added, the crystallization temperature becomes higher as the dissociation energy becomes larger, the storage characteristics are good, and it can cope with a high linear velocity. You can see that

On the other hand, according to Comparative Example 1, in the case of Sb ₇₅ Te ₂₅ , this corresponds to a high linear velocity, but the mark has disappeared by the storage test. This is because the crystallization temperature is extremely low. Also, it can be seen that Sb ₆₈ Te ₂₇ Ge ₅ of Comparative Example 2 has good storage characteristics, but is difficult to cope with a high linear velocity. This is because the additive element Ge has a covalent bond radius of 1.
It is considered that it does not work as a crystal nucleus because it is as small as 22 °.

On the other hand, Sb and Te are the main components, and Ba having a covalent bond radius of 1.98 ° and a dissociation energy of 10
Example 4 in which 8 kcalmol ^-1 of Si was added, and Example 5 in which Gd having a covalent bond radius of 1.62 ° and Ge having a dissociation energy of 109 kcalmol ^-1 were added.
In with a covalent bond radius of 1.50 ° and dissociation energy,
Also in the case of Example 6 in which 84.7 kcalmol ^-1 of B was added, high linear velocity was possible and the storage characteristics were good due to the cooperation of the two added elements. Also, Si and Ge
When B is added, the recording sensitivity is better than B. This is presumably because Ge and Si form a rank as an acceptor in the Sb-Te alloy, thereby improving light absorption efficiency.

In addition, Sb and Te are the main components, and In has a covalent bond radius of 1.50 ° and a covalent bond radius of 1.61.
Ｔ Tb and dissociation energy is 109 kcalmol ^-1
Example 7 wherein Ge was added and the covalent bond radius was 1.54.
Example 8 in which Pd of Å, Gd having a covalent bond radius of 1.62Å, and Ge having a dissociation energy of 109 kcalmol ⁻¹ was also added, capable of coping with high linear velocities and having good storage characteristics.

Further, Bi containing Sb and Te as main components, a covalent bond radius of 1.50 °, and a dissociation energy of 4
Ag of 6.8 kcalmol ^-1 and dissociation energy of 1
Example 9 in which P of 33.8 kcalmol ^-1 was added, Ca having a covalent bond radius of 1.74 ° and a dissociation energy of 7
Example 10 in which Cl having a dissociation energy of 86 kcalmol ^-1 was added similarly to Au of 5.9 kcalmol ^-1 also showed good characteristics. In particular, Ag has a slightly lower crystallization temperature of 165 ° C., probably because the dissociation energy is smaller than other elements, but there is no particular problem. Example 10
The recording sensitivity was good, probably because Cl worked as a donor to improve the light absorption. Further, all of the above embodiments have good repetition characteristics.

[0067]

(1) As is clear from the above description,
The optical recording medium according to any one of claims 1, 2 and 3 comprises Sb and Te as main components of the recording layer material, and has a covalent bond radius of 1.
There from 5Å between 1.7 Å, and the dissociation energy is La, Ce, Pr, Gd, Tb, a predetermined amount adding at least one kind of element selected from Lu, which is between 76Kcalmol ^-1 of 95Kcalmol ^-1 By doing so, it is possible to provide a recording medium having good storage characteristics and high repetition characteristics for high linear velocity. (2) The optical recording medium according to any one of claims 4, 5 and 6, wherein Sb and Te are the main components of the recording layer material, and Ca, Sr, whose covalent bond radius is between 1.4 ° and 2.0 °. Y, I
n, Ba, Hf, Dy, Sm, Zr, Ho, Pb, E
at least one element selected from u, Bi, Gd, Tb, Sc, Sn, Yb, and Na;
A between kcalmol ^-1 and 110 kcalmol ^-1
g, Au, Cu, Ga, Al, Ge, Si, B, N,
P, As, Cl, F, Br, I, Ti, Se, S, H,
By adding at least one element selected from Tb and Gd, it is possible to provide a recording medium having good protection characteristics and repetition characteristics corresponding to a high linear velocity and improved recording sensitivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a layer configuration of an example of an optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower heat protection layer 3 Recording layer 4 Upper heat protection layer 5 Reflection heat dissipation layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Shibaguchi, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Eiko Suzuki 1-3-6, Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H111 EA04 EA23 FB04 FB05 FB06 FB07 FB09 FB10 FB12 FB17 FB18 FB20 FB21 FB24 5D029 JA01

Claims (6)

[Claims] 1. An optical recording medium having a recording layer containing Sb and Te as main components, wherein the recording layer further has a covalent bond radius between 1.5 ° and 1.7 °, and Sb or Te.
Dissociation energy from 70 kcalmol ^-1 to 9
An optical recording medium characterized by adding at least one kind of element between 5 kcalmol ^-1 . 2. At least one of the elements whose covalent radius is between 1.5 ° and 1.7 ° and whose dissociation energy for Sb or Te is between 70 kcalmol ⁻¹ and 95 kcalmol ⁻¹ is La, Ce, or Pr, G
2. The method according to claim 1, wherein the element is selected from d, Tb, and Lu.
The optical recording medium according to the above. 3. When the at least one element whose covalent bond radius is between 1.5 ° and 1.7 ° and whose dissociation energy for Sb or Te is between 70 kcalmol ⁻¹ is A, the recording layer material is SbαTeβ representing composition
3. The light according to claim 1, wherein the composition (atm%) in the formula of Aγ is 60 ≦ α ≦ 80, 20 ≦ β ≦ 35, and 0 <γ ≦ 15 (where α + β + γ = 100). recoding media. 4. It has a recording layer containing Sb and Te as main components.
Optical recording medium, wherein the recording layer further comprises a covalent bond radius.
Is at least one of the elements between 1.4% and 2.0%
Kind and dissociation energy for Sb or Te is 45k
calmol ^-1From 110 kcalmol^-1Between
Characterized by the addition of at least one of the elements
Optical recording medium. 5. The covalent bond radius according to claim 4, wherein the radius is 1.4 °.
At least one of the elements between
a, Sr, Y, In, Ba, Hf, Dy, Sm, Zr,
Ho, Pb, Eu, Bi, Gd, Tb, Sc, Sn, Y
b, selected from Na and having a dissociation energy for Sb or Te of 45 kcalmol ^-1 to 110 kcalmol
^At least one of the elements between ^-1 is Ag, Au, C
u, Ga, Al, Ge, Si, B, N, P, As, C
The optical recording medium according to claim 4, wherein the optical recording medium is selected from the group consisting of 1, F, Br, I, Ti, Se, S, H, Tb, and Gd. 6. The method according to claim 1, wherein at least one element having a covalent bond radius of between 1.4 ° and 2.0 ° has a dissociation energy for X, Sb or Te of 45 kcalmol ⁻¹ to 110 kcal.
at least one element between kcalmol ^-1
SbαTeβXγ representing the composition of the recording layer material
In the formula of Yδ, the composition (atm%) is 55 ≦ α ≦ 80, 20 ≦ β ≦ 35, 0 <γ <10, 0 <
6. The optical recording medium according to claim 4, wherein δ ≦ 10 (where α + β + γ + δ = 100).