JPH11321102A - Phase change optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high recording density optical recording medium having excellent repeating recording characteristics and used for a high recording density equivalent or more to that of a DVD-RAM or a DVD-ROM and an optical recording medium having good repeating recording characteristics corresponding to a highly liner speed by extending a recordable linear speed range to a highly linear speed. SOLUTION: In the optical recording medium comprising a recording layer made of an Ag-Sb-Te phase change recording material, the layer utilizes a change of optical properties of a phase transfer between a crystallized state having a single or a plurality of crystal phases each containing at least one metastable crystal phase and an amorphous state made of an amorphous phase in such a manner that a composition at an atomic ratio of the layer is a composition formula represented by Aga Sbx Te(1-a-x) , wherein x is in a range of 0.72<=x+2a<=0.80, and a single or a plurality of crystal phases belong to a space group Fm3m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase changeable optical disk or the like, which irradiates a light beam to cause an optical change in a recording layer material so that information can be recorded, reproduced, and rewritten. The present invention relates to a variable optical recording medium.

[0002]

2. Description of the Related Art As one of optical recording media capable of recording, reproducing and erasing information by irradiating a laser beam, a so-called phase-change optical recording medium utilizing a transition between a crystal and an amorphous phase or between a crystal and a crystal phase. Is well known. This is characterized in that overwriting with a single beam is possible and the optical system on the drive side is simpler, and is applied as a computer-related or audio-visual recording medium.

As one of the recording materials, (Sb _x T
e _1-x) having composition formula of M _y is, JP-A-1-277338
No. 6,086,045. Here, M is Ag, Al,
As, Au, Bi, Cu, Ga, Ge, In, Pb, P
at least one element selected from t, Se, Si, Sn and Zn, in a composition range of 0.4 ≦ x <0.7, and
y ≦ 0.2. The structure in this composition range is based on Sb ₂ Te ₃ . However, in the case of the recording layer having this structure, there was a problem in the repetitive recording characteristics in the region where y was 0.7 or more. In a similar material system, (Sb _x Te _1-x ) _a M
A phase change recording material represented by _a composition formula _1-a (M is at least one element of Au, Ag, and Cu) is disclosed in
No. 71049. This composition range is 0 <x <0.9 and 0 <a <1, and the structure is S
b ₂ Te ₃ + Sb. In the vicinity of the eutectic composition of the Sb ₂ Te ₃ -Sb pseudo-binary system, there is a difference in crystallization speed between Sb and Sb ₂ Te ₃ , and the boundary between the amorphous portion and the crystallized portion is
Disturbance is likely to occur due to the influence of the grain boundaries of Sb and Sb ₂ Te ₃ . For this reason, it can be applied to a medium having a relatively low recording density such as a CD-RW, but a DVD-RAM or a DVD-R
At a high recording density equal to or higher than OM, it was difficult to obtain good recording characteristics.

That is, in the Sb-Te-M system, Sb ₂ T
Ag, based on the structure of e ₃ , Sb ₂ Te ₃ + Sb,
Al, As, Au, Bi, Cu, Ga, Ge, In, P
With the addition of b, Pt, Se, Si, Sn and Zn, only a recording material having improved amorphous state stability, high-speed erasing characteristics, or repeated recording characteristics was used. , Sb-Te-M recording material,
There has been no knowledge about a recording medium having one or more metastable crystal phases belonging to the space group Fm3m, and a composition having the metastable crystal phase that can exist and has durability against thermal shock during repeated recording. There was no prior art that clarified the area. For this reason, the relationship between the composition of the recording layer having a metastable crystal phase and the repetitive recording, or the relationship between the composition and the crystal structure, and the relationship between the crystal structure and the repetitive recording characteristics are not clear, and high recording densities such as DVD -RAM and DV
There has been no optical recording medium having a recording density equal to or higher than that of a D-ROM and having good recording characteristics. In addition, the relationship between the composition region having good repetition and the recording linear velocity has not been clear conventionally.

[0005]

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a high-density recording medium which is used at a high recording density equal to or higher than that of a DVD-RAM or a DVD-ROM and which has excellent repetitive recording characteristics. To provide a medium. A second object of the present invention is to extend the crystallization speed of the Ag-Sb-Te-based recording layer to a high linear velocity region, and achieve a predetermined recording linear velocity, in particular, a CD-RW, a DVD-RAM, or a DVD.
-Recording linear velocity 1.2 m / s, 2.4 m / s, 3.5 corresponding to rewritable phase change optical recording medium compatible with ROM
An object of the present invention is to provide an optical recording medium having good repetitive recording characteristics corresponding to m / s, 6 m / s, and 7 m / s.

[0006]

According to the present invention, first, in an optical recording medium having an Ag-Sb-Te phase change optical recording material as a recording layer, the recording layer has at least one metastable crystalline phase. using a change in optical properties of the phase transition between the amorphous state consisting of crystalline state and an amorphous phase having one or more crystalline phases including, yet the composition at the atomic ratio of the recording layer Ag _a In the composition formula represented by Sb _x Te _(1-ax) , _x representing the composition of Sb is in the range of 0.72 ≦ x + 2a ≦ 0.80, and the single or plural crystal phases are in the space group Fm3.
A phase-change optical recording medium characterized by being a crystalline phase belonging to m. Secondly, there is provided an optical recording medium according to the first aspect, wherein the crystal phase in the crystallized recording layer is a metastable Ag-Sb-Te solid solution single phase. Thirdly, in the first or second, Ag _a Sb _x T
e The composition of the _(1-ax) recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.05 ≦ a ≦ 0.09, and the recording linear velocity region is at least 1.2.
A phase change optical recording medium characterized by including m / s is provided. Fourth, in the above first, second or third, the composition of the Ag _a Sb _x Te _(1-ax) recording layer is 0.72 ≦ x + 2a ≦ 0.80 and 0.03 ≦ a ≦ 0. 07 and the recording linear velocity region is at least 2.4.
A phase change optical recording medium characterized by including m / s is provided. Fifth, the first, second, the third or _{fourth, Ag a Sb x Te (1} -ax) The composition of the recording layer is 0.72 ≦ x + 2a ≦ 0.80 and 0.02 ≦ a ≤ 0.06 and the recording linear velocity region is at least 3.5.
A phase change optical recording medium characterized by including m / s is provided. Sixth, the first, second, third, in the fourth or _{fifth, Ag a Sb x Te (1} -ax) The composition of the recording layer is 0.72 ≦ x + 2a ≦ 0.80 and 0. 015 ≦ a ≦ 0.05 and the recording linear velocity region is at least 6 m /
and a phase change optical recording medium characterized by including s. Seventh, the first, second, third, fourth,
In the fifth or sixth aspect, the composition of the Ag _a Sb _x Te _(1-ax) recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.01 ≦ a ≦ 0.04, and The recording linear velocity area is at least 7 m /
and a phase change optical recording medium characterized by including s. Eighth, the crystallized portion of the recording layer after the initial crystallization has a metastable Sb ₃ Te crystal phase belonging to the space group Fm3m, and one or more crystals in a lattice matching relationship with the metastable Sb ₃ Te crystal phase. An optical recording medium characterized by having a crystal phase of Ninth, in an optical recording medium having a recording layer of a phase change recording material having a group Ib element, a group Vb element, and a group VIb element with Sb and Te as essential elements,
The recording layer utilizes a change in optical properties in a phase transition between a crystallization state having one or more crystal phases including at least one metastable crystal phase and an amorphous state having an amorphous phase, and In the composition formula in which the composition at the atomic ratio of the recording layer is represented by (Ib) a (Vb) x (VIb) _(1-ax) , x representing the composition of the Vb element is 0.72 ≦ x + 2a ≦ 0. .80, and the one or more crystal phases are in the space group Fm3.
A phase-change optical recording medium characterized by being a crystalline phase belonging to m.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The recording layer of the phase-change optical recording medium according to the first aspect of the present invention is formed of Ag
An -Sb-Te-based recording material in which the recording layer changes optical properties in a phase transition between one or more crystalline phases including at least a metastable crystalline phase and a metastable amorphous phase. The composition of the recording layer is expressed as A in the atomic ratio of the recording layer.
In _a composition formula represented by g _a Sb _x Te _(1-ax) , _x representing the composition of Sb is characterized by being in a range of 0.72 ≦ x + 2a ≦ 0.80. Here, the recording layer is characterized by having at least a metastable crystal phase belonging to the space group Fm3m. This metastable crystal phase is Ag-Sb-
Te solid solution, Sb-Te solid solution, at least one of Sb ₃ Te. These metastable crystal phases have the space group F
It is either a crystal phase belonging to m3m and having a lattice constant of about 0.608 nm or a long-period crystal phase in which the elements in the Fm3m crystal are ordered. The region where these metastable phases exist is a region where the condition of 0 ≦ 4a <1 is satisfied in the above composition formula.

Particularly, the one in which the crystallized portion of the recording layer is composed of a single-phase metastable crystal phase is the second one described in the present invention, and is an Ag-Sb-Te solid solution. In addition, any combination of the above metastable crystal phases may be used as a mixed phase state composed of a plurality of crystal phases consisting only of the metastable phase. Further, it may have another stable crystal phase having a lattice matching relationship with these metastable phases, that is, an AgSbTe ₂ crystal phase.
For example, a _{Sb 3 Te + AgSbTe 2 Sb 3} Te + Ag-Sb-Te solid solution. In each case, the crystal structure is based on a face-centered cubic lattice having a lattice constant of about 0.608 nm. In order to obtain a good mark shape, the crystallized portion of the recording layer has a single phase A
It is preferred that the g-Sb-Te metastable phase only be used.
Even if an excessive thermal shock during the initial crystallization cannot be avoided and a crystal phase of a phase separation is unavoidably generated, the crystal phases belonging to the space group Fm3m having a lattice-matching relationship with each other are mainly generated, and AgSbTe ₂ and the lattice Other precipitates that do not have a matching relationship, for example, Sb, Sb ₂ Te ₃ or an amorphous phase in the crystallized portion do not appear as much as possible, and an initial crystal suitable for generating a crystal phase belonging to the space group Fm3m including the metastable phase The conversion process is adopted. The present invention may have a composition gradient in the film thickness direction or the in-plane direction, and includes a layered film of the above phases.

The crystallization rate of the optical recording medium according to the present invention has composition dependence. For this reason, it is important to adjust the optimum composition in accordance with each recording linear velocity. The optical recording medium according to the third aspect of the present invention aims at a recording linear velocity of 1.2 m / s, and in the first or second aspect of the present invention, Ag _a Sb _x T
The composition of the e _(1-ax) recording layer is characterized by being in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.05 ≦ a ≦ 0.09.

An optical recording medium according to a fourth aspect of the present invention is intended to cope with a recording linear velocity of 2.4 m / s, and in the first, second or third aspects of the present invention, Ag _a Sb _x Te _{(1 -ax)} The composition of the recording layer is characterized by being in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.03 ≦ a ≦ 0.07.

The optical recording medium according to the fifth aspect of the present invention is intended to cope with a recording linear velocity of 3.5 m / s. In the first, second, third or fourth aspects of the present invention, Ag _a Sb _x Te
The composition of the _(1-ax) recording layer is characterized by being in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.02 ≦ a ≦ 0.06.

An optical recording medium according to a sixth aspect of the present invention is intended to cope with a recording linear velocity of 6 m / s.
In the second, third, fourth or fifth, Ag _a Sb _x Te
The composition of the _(1-ax) recording layer is characterized in that the composition satisfies 0.72 ≦ x + 2a ≦ 0.80 and 0.015 ≦ a ≦ 0.05.

An optical recording medium according to a seventh aspect of the present invention is intended to cope with a recording linear velocity of 7 m / s.
In the second, third, fourth, fifth or sixth, Ag _a Sb _x
It is characterized in that the composition of the Te _(1-ax) recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.01 ≦ a ≦ 0.04.

An eighth aspect of the present invention is that the crystallized portion of the recording layer after the initial crystallization has a metastable Sb ₃ Te belonging to the space group Fm3m.
It is characterized by having a crystal phase and having one or more crystal phases in lattice matching with the metastable Sb ₃ Te crystal phase. The one or more crystal phases that have a lattice matching relationship with the metastable Sb ₃ Te crystal phase may be a phase change material or a non-phase change material. Further, it may be a stable phase or a metastable phase. For example, InTe, In ₃ SbTe ₂ , Al ₃ Sb
Te _{2 and} so on.

An optical recording medium according to a ninth aspect of the present invention comprises Sb,
Te as an essential element, a group Ib element, a group Vb element, and
In an optical recording medium having a recording layer made of a phase change recording material having a group VIb element, the recording layer has a crystallized state having one or more crystal phases including at least one metastable crystal phase and an amorphous state having an amorphous phase. (Ib) _a (Vb) _x (VIb) _(1-ax) using the change in the optical properties in the phase transition between
X representing the composition of the Vb element is in the range of 0.72 ≦ x + 2a ≦ 0.80, and the single or plural crystal phases are in the space group Fm3.
It is characterized by being a crystal phase belonging to m.

[0016]

Ag-Sb-Te3 used first in the present invention
The phases that can appear in the crystal phase of the elemental recording material include simple, binary, and ternary compounds, alloy phases, and solid solutions. Among them, AgSbTe ₂ , Ag—Sb—Te solid solution, and Sb ₃ T
e, Sb ₂ Te ₃ and Sb tend to appear. Among them, Ag
The crystal structures of SbTe ₂ , Ag—Sb—Te solid solution, and Sb ₃ Te belong to the space group Fm3m and have a lattice constant of 6.08 nm.
, These crystal phases are in lattice matching with each other. First, the crystallized portion of the recording layer is a single-phase Ag-Sb
-When only the Te recording layer is formed, there is no grain boundary,
Even if there is a crystal grain boundary, the crystal grain boundary has a relatively good lattice junction, there are no large voids in the crystal grain boundary, and unevenness in thermal conductivity hardly occurs. For this reason, an amorphous portion caused by a grain boundary such as a coarse crystal ring
Disturbance of the boundary of the crystallized portion is less likely to occur, and a smooth boundary between the amorphous portion and the crystallized portion faithfully reflecting the intensity distribution and the temporal profile of the light beam is obtained, and a good jitter value is obtained up to the high density recording area. can get. High stability composition region to thermal shock at the time of recording of the metastable phase can, Ag _a S
The composition of the b _x Te _(1-ax) recording layer is 0.72 ≦ x + 2a ≦
0.80 and 4a <1, which means that even if the metastable Ag—Sb—Te solid solution undergoes the first phase transition, AgSbTe ₂ + metastable Sb ₃
Te is a plurality of crystal phases including the above-mentioned metastable phase having a lattice matching relationship with each other, and is therefore a composition region that maintains relatively good recording characteristics. In addition, AgSbTe
₂ and metastable Sb ₃ Te have a difference in crystallization speed,
The amount of AgSbTe ₂ is very small, and the main part is preferably metastable Sb ₃ Te, and the range of a ≦ 0.09 is particularly preferable.

On the other hand, as in the prior art, when the crystallized portion of the recording layer is composed of a plurality of crystal phases that do not have a lattice matching relationship, and when the plane matching at the crystal grain boundary is not good, the crystal boundary is Vacancies and segregation occur, and unevenness in thermal conductivity occurs at these grain boundaries. Furthermore, since the crystallization speed generally differs for each crystal grain, the boundary between the crystal and the amorphous portion tends to reflect the crystal grain boundary, and as a result, the boundary between the amorphous portion and the crystallization portion is disturbed, Good characteristics cannot be obtained in a high recording density region. Further, when the crystal grain size is set to a fine crystal of several nm, there is a certain effect in obtaining the smoothness of the crystal grain boundary, but a problem still remains in a high recording density region. In this case, at grain boundaries that are not lattice-matched to each other, undesired effects such as a decrease in crystallization speed and corrosion from grain boundaries also occur due to an increase in strain and interfacial energy at the interface portion. Is not suitable for high recording density. On the other hand, in the present invention, even when the crystallized portion of the recording layer is composed of a plurality of crystal phases, the generated crystal phases belong to the same space group and have close lattice constants. The same good bonding as in the case of is obtained. For this reason, it has the recording characteristics according to the single-phase case. Since the crystallization speed of the metastable phase is higher than the crystallization speed when a stable phase is generated and is suitable for high-speed overwriting, the recording linear velocity region can be extended to a high linear velocity.

In the initial crystallization of the optical recording medium according to the present invention, an initial crystallization method suitable for the precipitation of a metastable phase, for example, a melting initialization method using a laser beam is employed. A particularly preferred structure is A 2 described in the second aspect of the present invention.
g-Sb-Te is a metastable solid solution single phase. When the condition (4a = 1) where the stability of the metastable phase is poor is satisfied,
The recording layer has a very low crystallization rate and is not suitable for high-speed recording. As described above, although the crystallization rate of the Ag—Sb—Te-based recording layer has composition dependence, as the Ag or Te concentration in the recording layer increases, the recording layer becomes more suitable for the lower recording linear velocity side. As the recording layer composition increases, the recording layer composition becomes more suitable for high recording linear velocity.

In the case of a recording strategy (a light emission pattern of an LD during recording) employed in a CD-RW, a recording linear velocity is 1.2 m / s, 2.4 m / s, 3.5 m / s, 6 m / s.
Ag concentrations corresponding to s and 7 m / s were 0.0% respectively.
5 ≦ a ≦ 0.09, 0.03 ≦ a ≦ 0.07, 0.02
≦ a ≦ 0.06, 0.015 ≦ a ≦ 0.05, 0.01
≦ a ≦ 0.04.

When the Ag concentration is set to 0 and the recording layer after the initial crystallization becomes metastable Sb ₃ Te,
Recording is possible. However, in this case, the composition for obtaining the optimum repetitive recording characteristics is Sb ₃ Te having a stoichiometric composition, and it is difficult to adjust the crystallization rate. However, better recording characteristics can be obtained than a recording layer having the same composition of Sb + Sb ₂ Te ₃ , and recording characteristics according to the Ag-Sb-Te system can be obtained at an optimum recording linear velocity. If a small amount of one or more crystal phases having a lattice matching relationship with Sb ₃ Te is added to the Sb ₃ Te, the crystallization rate can be controlled without impairing the repetitive recording characteristics.

Further, recording is possible even when all or a part of any of the above-mentioned elements of Ag and In and a part of Sb and Te are replaced with elements having similar atomic radii with homologous elements. In this case, similarly to the above, the composition is (Ib) _a (Vb) _x
(VIb) In the composition formula represented by _(1-ax) , when x representing the composition of the Vb element is in the range of 0.72 ≦ x + 2a ≦ 0.80, a crystal phase belonging to the space group Fm3m appears. However, it shows stable characteristics against repeated recording.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a conceptual diagram showing the layer structure of an optical recording medium according to one embodiment of the present invention. In FIG. 1, a first protective layer 2 made of ZnS.SiO _{2 is formed} on a polycarbonate substrate 1 having a guide groove (not shown), and Ag-Sb- on the first protective layer.
Te recording layer 3, second protection layer 4 made of ZnS · SiO ₂ on the recording layer, Al-Ti reflective heat dissipation layer 5 on the second protective layer, environmental protection consisting of UV curable resin on the reflective heat dissipation layer Layer 6 is laminated. FIG. 2 shows Embodiment 1 of the present invention.
FIG. 4 is a diagram showing an example of an X-ray diffraction pattern after initial crystallization of a recording layer used for the method. AgSbTe ₂ , metastable Ag-S
Diffraction peaks corresponding to the b-Te solid solution and Sb ₃ Te are observed, and no diffraction peaks of Sb and Sb ₂ Te ₃ which are stable phases are observed. This result is consistent with the TEM observation.

Table 1 shows the relationship between the number of repetitive recordings of the optical recording medium having the structure shown in FIG. 1 and the composition of the recording layer and the crystal structure after initialization, together with comparative examples.
The number of repetitive recordings is determined by the maximum number of repetitive recordings in which the jitter value σ / Tw normalized by the window width Tw satisfies the standard value (σ / Tw ≦ 13%). The initial crystallization of all the optical recording media except for Comparative Example 3 was performed by irradiation with a large-diameter LD beam. The initial crystallization in Comparative Example 3 was performed by lamp annealing. As shown in Examples 1-1 to 11 of Table 1, 0.72 ≦ x
When the condition of + 2a ≦ 0.80 is satisfied, the crystal structure of the initial crystallization becomes fcc by an appropriate initialization method such as high-speed initialization by LD beam irradiation, and the number of repetitive recordings exceeds 1,000. . Outside this composition range, the appearance of Sb and Sb ₂ Te ₃ is observed. That is,
In Comparative Example 1, the number of repetitive recordings was reduced due to the precipitation of Sb ₂ Te _{3, and} the number of repetitive recordings in Comparative Example 2 in which Sb was precipitated was low.

The recording linear velocity particularly has a relationship with the Ag concentration. The optimum Ag concentration for a given recording linear velocity depends on the strategy, but when a strategy (multi-pulse light emission pattern of LD at the time of recording) applied to CD-RW is used, 1.2 m / s; 4m / s,
The regions of the parameter Ag concentration corresponding to 3.5 m / s, 6 m / s, and 7 m / s are 5 to 9 at. % (Examples 4, 5-1, 6-1 and 7-1), 3 to 7 at. % (Examples 1-2, 5-2, 6-2, 7-2, 8-1), 2 to 6
at. % (Examples 1-1, 2, 3, 6-3, 7-3, 8
-2, 9-1), 1.5 to 5 at. % (Examples 1-3,
7-4, 8-3, 9-2, 10-1), 1-4 at. %
(Examples 1-4, 8-4, 9-3, 10-2, and 11).

In Comparative Example 1 in which the value of the parameter x + 2a is less than 0.72, the repetitive recording characteristics deteriorate due to the thermal shock accompanying overwriting. In Comparative Example 2 in which the value of the parameter x + 2a exceeds 0.80, the repetitive recording characteristics also deteriorate due to the thermal shock accompanying overwriting.
Further, as shown in Comparative Example 3, 0.72 ≦ x + 2a ≦
Even if the condition of 0.80 is satisfied and the metastable phase can be present in the composition region, the stable phases such as Sb ₂ Te ₃ and Sb are deposited without the metastable phase being precipitated such as initialization by lamp annealing. In this case, good high-density recording cannot be realized. Since the metastable phase is phase-separated into a stable phase by prolonged high-temperature annealing, it is preferable that the initialization be completed in a short time.

In the present invention, it is possible to add an optional additive element to the recording layer. For example, Sb ₃ T
e, a crystal phase having a lattice matching relationship with e, for example, In ₃ SbT
In order to precipitate e, a small amount of In ₃ SbTe may be added to the recording layer. In the case where an element which is in a chemical bonding state with any of Ag, Sb, and Te is added, the composition formula of Ag-Sb-Te excluding the ratio of bonding with the element corresponds to the present invention. In addition, when a substitution-type additive element for substituting a specific element in a crystal is added, the composition formula of the present invention is changed taking this into consideration. Examples 12-1
As shown in Table 5 (Table 2), Bi is for Sb, Se is for Te, Au is for Ag, and the general composition formula in this case is that Sb and Te are essential elements. (I
b) _a (Vb) _x (VIb) _(1-ax) In each case, a metastable crystal phase exists within the range of the above composition formula, and the repetitive recording characteristics become good. The layer structure of the optical recording medium used in the present invention is not limited to the above, and any structure of a known optical recording medium is possible.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

As described above, the phase change optical recording medium of the present invention has the following outstanding effects. B) Recording can be performed at a higher recording density than DVD-RAM or DVD-ROM, and the number of repetitive recordings is improved. B) The recordable linear velocity area is extended to high linear velocity, and 1.2m
/ S, 2.4 m / s, 3.5 m / s, 6 m / s, 7 m /
The optical recording medium corresponding to s has been realized.

[Brief description of the drawings]

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

FIG. 2 is a view showing an X-ray diffraction pattern of a recording layer used in Example 1 after initial crystallization.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st protective layer 3 recording layer 4 2nd protective layer 5 reflective heat dissipation layer 6 environmental protection layer

Claims (9)

[Claims] 1. An optical recording medium having an Ag—Sb—Te phase-change optical recording material as a recording layer, wherein the recording layer has a crystallization state having one or more crystal phases including at least one metastable crystal phase. using a change in optical properties of the phase transition between the amorphous state of an amorphous phase, yet the composition at the atomic ratio of the recording layer Ag _a Sb _x T
In the composition formula represented by e _(1-ax) , x representing the composition of Sb
Is in the range of 0.72 ≦ x + 2a ≦ 0.80, and the single or plural crystal phases are in the space group Fm3.
A phase-change optical recording medium, which is a crystalline phase belonging to m. 2. The optical recording medium according to claim 1, wherein the crystalline phase in the crystallized recording layer is a metastable Ag—Sb—Te solid solution single phase. 3. The method of claim 1, wherein Ag _a Sb _x T
e The composition of the _(1-ax) recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.05 ≦ a ≦ 0.09, and the recording linear velocity region is at least 1.2.
A phase change optical recording medium characterized by containing m / s. 4. The method according to claim 1, 2 or 3, wherein Ag _a S
The composition of the b _x Te _(1-ax) recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.03 ≦ a ≦ 0.07, and the recording linear velocity region is at least 2.4.
A phase change optical recording medium characterized by containing m / s. 5. The method according to claim 1, 2, 3, or 4, wherein Ag is
_a The composition of the Sb _x Te _(1-ax) recording layer is 0.72 ≦ x +
2a ≦ 0.80 and 0.02 ≦ a ≦ 0.06, and the recording linear velocity region is at least 3.5.
A phase change optical recording medium characterized by containing m / s. 6. The method according to claim 1, 2, 3, 4, or 5,
_{Ag a Sb x Te (1-} ax) The composition of the recording layer is in the range of 0.72 ≦ x + 2a ≦ 0.80 and 0.015 ≦ a ≦ 0.05, and the recording linear velocity region of at least 6m /
A phase change optical recording medium characterized by containing s. 7. The composition of claim 1, 2, 3, 4, 5, or 6, wherein the composition of the Ag _a Sb _x Te _(1-ax) recording layer is 0.72 ≦ x + 2a ≦ 0.80 and 0.01. ≦ a ≦ 0.04 and the recording linear velocity region is at least 7 m /
A phase change optical recording medium characterized by containing s. 8. A crystallized portion of the recording layer after the initial crystallization has a metastable Sb ₃ Te crystal phase belonging to a space group Fm3m,
An optical recording medium having one or more crystal phases in lattice matching with the metastable Sb ₃ Te crystal phase. 9. An optical recording medium having a phase-change recording material containing a group Ib element, a group Vb element, and a group VIb element with Sb and Te as essential elements, wherein the recording layer has at least one metastable material. Utilizing a change in optical properties in a phase transition between a crystallization state having one or more crystal phases including a crystal phase and an amorphous state having an amorphous phase, and furthermore, the composition of the recording layer in the atomic ratio To (I
b) In a composition formula represented by a (Vb) x (VIb) _(1-ax) ,
X representing the composition of the Vb element is in the range of 0.72 ≦ x + 2a ≦ 0.80, and the single or plural crystal phases are in the space group Fm3.
A phase-change optical recording medium, which is a crystalline phase belonging to m.