JPS6169935A - Spectral reflectance variable alloy and recording material - Google Patents

Abstract

PURPOSE:To obtain a spectral reflectance variable alloy for data recording, display and sensor using the change of spectral reflectance with the change of crystal structure of alloy by optical and thermal energy, which is obtained by including the specified amount of Cu, Al and Mn. CONSTITUTION:A Cu alloy includes Cu mainly, by weight, 14-16.5% Al and 0.01-15.0% Mn. The Cu alloy is the spectral reflectance variable alloy, which has the different crystal structure between the first temperature (high temperature) than room temperature in a solid state and the lower temperature (low temperature) state than the first temperature and the different crystal structure as that by non-quenching in the low temperature by quenching from the high temperature. The Cu alloy has a different phase of the crystal structure in at least two temperature areas on the solid phase, the different spectral reflectance between the quenched state of a high temperature phase and low temperature phase state of non-quenching in a standard state and the characteristic of variable spectral reflectance by heating and quenching in the high temperature phase area, and heating and cooling in the low temperature phase area.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a novel alloy with variable spectral reflectance and a recording material, and in particular to a novel alloy with variable spectral reflectance and a recording material, and in particular, the spectral reflectance of the alloy changes as the crystal structure of the alloy changes due to the application of light and thermal energy. This invention relates to alloys that can be used as media for information recording, display, sensors, etc. that utilize change.

[Background of the invention]

In recent years, as information recording becomes more dense and digital, various information recording and reproducing methods are being developed. Especially for recording information using laser light energy.

The optical disks used for erasing and reproducing are capable of higher recording density than magnetic disks, as described in Industrial Rare Metals N80, 1983 (Optical Disks and Materials), and will be a promising method for recording information in the future. . this house,
The laser playback device is a compact disc (CD)
It has been put into practical use as

On the other hand, recordable methods can be broadly divided into two types: write-once type and rewritable type. The former can only be written once and cannot be erased. The latter is a method that allows repeated recording and erasing. In the write-once type recording method, a laser beam is used to destroy or shape the recording portion of the medium to create unevenness, and for reproduction, a change in the amount of light reflected due to the interference of the laser beam at the uneven portion is used for reproduction. For this recording medium, it is generally known that Te or its alloy is used to form irregularities by melting and sublimating Te. This type of medium has some problems such as toxicity. Magneto-optical materials are the mainstream for rewritable recording media. This method uses optical energy to invert and record the local magnetic anisotropy of the medium near the Curie point or the compensation point temperature, and the polarization plane of the polarized incident light at that part is caused by the magnetic Faraday effect and magnetic Kerr effect. Play with the amount of rotation. This method is considered to be the most promising rewritable method, and active research and development is underway with the aim of putting it into practical use in the next few years. However, there is currently no material with a large amount of rotation of the plane of polarization, and even with various measures such as multilayer film formation, there is a big problem that output levels such as S/N and C/N are low.

Other rewritable systems utilize reflectance changes due to reversible phase changes between amorphous and crystalline recording media. For example, National Technical
There is an alloy in which small amounts of Ge and Sn are added to T e Ox described in Report Vol. 129 Ha 5 (1983).

However, this method has a major problem in that the crystallization temperature of the amorphous phase is low, and the instability of the phase at room temperature affects the reliability of the disk.

On the other hand, as an alloy utilizing color tone change, JP-A-57-1
There are 40845. This alloy is (12-15)wt%A
Q-(1-5) An alloy consisting of wt% Ni-remaining Cu at the martensitic transformation temperature.

It takes advantage of the reversible change from red to gold. Martensitic transformation is a transformation that inevitably occurs as the temperature decreases, so the color tone obtained when maintained above the martensitic transformation temperature cannot be brought below the martensitic modulation temperature, and conversely, martensitic transformation If a color tone that can be obtained at a temperature below this temperature is raised above the martensitic transformation temperature, it will undergo transformation and change to a different color tone.Therefore, it is impossible to obtain two color tones that occur above and below the martensitic transformation at the same time at the same temperature. Can not. Therefore, this 17 principle cannot be applied as a recording material.

[Purpose of the invention]

An object of the present invention is to provide a variable spectral reflectance alloy and a recording material that can maintain partially different spectral reflectances at the same temperature.

[Summary of the invention]

(Summary of R-ming) The present invention uses aluminum (AQ) 14 which has copper as its main component.
~16.5% by weight and manganese (Mn) 0.01~
The variable spectral reflectance alloy is characterized by being made of an alloy containing 15% by weight.

That is, the present invention provides a first temperature higher than room temperature (
An alloy having different crystal structures at a temperature lower than the first temperature (high temperature) and at a temperature lower than the first temperature (low temperature), characterized in that the alloy has a crystal structure different from that obtained by non-quenching at the low temperature due to quenching from the high temperature. It is an alloy with variable spectral reflectance.

The alloy of the present invention has a spectral reflectance of at least 2V1 at the same temperature by heating and cooling treatment in a solid state.

This allows the spectral reflectance to be changed reversibly.

That is, the alloy according to the present invention has at least 2
It has phases with different crystal structures in two temperature ranges, and among them, the spectral reflectance is different between the quenched state of the high temperature phase and the low sum state of the non-quenched standard state. The spectral reflectance changes reversibly by heating and cooling in the low phase temperature region.

The principle of reversible change in reflectance of the alloy of the present invention will be explained with reference to FIG.

Figure 1 shows the change in crystal structure due to phase transformation of Cu-AQ alloy, and this diagram can be used to record and record information such as 2 signals, 1 figure, and symbols required as a recording material. Explain the principle of erasing. In the alloy with composition (1) in the fE1 diagram, there are three phase states in the solid state. That is, there is a β single phase, a (β+γ) phase, and an (α+γ) phase. The crystal structure is α.

The single phase states of β and γ are different, so it is natural that they are used alone, but their optical properties also change depending on their mixed phase. Spectral reflectance will be explained as a difference in optical properties due to a difference in crystal structure. Is T1 the temperature at which what is recorded can be read? It can be safely thought of as room temperature. In the equilibrium state at T1, γ-rich
Since it is an (α+γ) phase, the spectral reflectance of the alloy is close to . When this is heated to a temperature of 100.degree. C. and rapidly cooled, the β phase is maintained at T1. The spectral reflectance of the β phase at T
The β phase at is copper-red and the (α+γ) phase is golden yellow. That is, the alloy in the (α+γ) phase state is irradiated with a laser beam having a diameter of, for example, several μm to locally heat it to T4, and then the laser irradiation is stopped. The irradiated area is rapidly cooled, and only the laser irradiated area becomes the β phase. Since the portion that is not irradiated with the laser remains in the (α+γ) phase, the spectral reflectance of the laser irradiated portion differs from that of the other portions at T1, making it possible to distinguish between the two. This state corresponds to the recording state. On the other hand, T
Heat to 4 and then cool quickly.

When a β phase kept at T1 is heated to a T higher than T1, the β phase changes to an (α+γ) phase, and even when the temperature is returned to T1, the (α+γ) phase remains.

Therefore, when a laser beam is irradiated to a portion locally made into a β phase by laser irradiation as described above and heated to a temperature of T, the β phase changes to an (α+γ) phase.

Even after the temperature is returned to T1, the (α+γ) phase state is maintained. In other words, this corresponds to erasure.

Note that in order to change the β phase to the (α+γ) phase, it is sufficient to heat the temperature to a temperature lower than T1, but the upper limit temperature is the temperature at which the β phase does not precipitate when maintained at a high temperature, Ta in Figure 1.
, that is, the eutectoid temperature.

The above process can be repeated and can be applied as a so-called rewritable recording medium.

Still other recording methods can be applied.

That is, a sample in a β phase state at a temperature T is used as a state before recording. For example, when this is irradiated with a laser beam having a diameter of several μm and heated to T2, the laser irradiated part changes to the (α+γ) phase. Even after cooling to a temperature of T1, the laser irradiation part remains (
It is an α+γ) phase, and can be distinguished from the β phase in the non-laser irradiated area by having a different spectral reflectance. Therefore, it can be recorded. Erasing can be done by heating the entire surface of the sample to T2 and then cooling it. This is because when such a treatment is performed, the entire surface changes to the (α+γ) phase at the temperature T1.

As described above, the present invention provides a material that can be recorded and erased by using an alloy that has at least two phases with different crystal structures in a solid state and maintains the phase in one temperature range in the other temperature range. It is.

According to the recording and erasing mechanism using light and thermal energy as described above, the composition of the alloy is limited as described above. In other words, the composition must be in a range that allows the high-temperature phase to be cooled appropriately by rapid cooling.

In the present invention, the β phase, which is stable at high temperatures, is rapidly cooled and maintained at a temperature at which recording can be read.

Therefore, in order to effectively realize recording and erasing by heating and quenching, reducing the heat capacity of the recording medium increases its response speed. Therefore, it is effective to form a thin film by directly rapidly cooling and solidifying it into a foil or film form from the gas phase or liquid phase. PVD (vapor deposition, sputtering, etc.) is a method for forming thin films.

There are CVD methods, molten metal quenching methods in which molten metal is poured onto metal rolls rotating at high speed and rapidly solidified, methods in which fine powder is applied and fired, electroplating, chemical plating, and the like. The crystal grains of the foil or thin film are preferably as fine as possible in order to locally change the spectral reflectance and obtain a high electrical signal output. The above-mentioned method generally forms a foil or film in a rapidly cooled state, so the crystal grains are very fine, and it is very suitable as a method for producing a recording medium. Furthermore, from the viewpoint of reducing heat capacity, it is very effective to powder the metal or alloy of the recording medium. It is more effective to mix this with a binder and apply it to form a film. In the case of a film formed on a substrate as described above, it is also effective to divide the film into the minimum size of the recording unit by chemical etching or the like to reduce the heat capacity of each film.

By utilizing the reversible changes in spectral reflectance and color tone as described above, it can be applied not only to recording media such as optical disks and memories, but also to sensors such as display elements and temperature sensors.

(Alloy Composition) The alloy of the present invention has different crystal structures at high and low temperatures, and the rapidly cooled crystal structure must be formed by rapid cooling from a high temperature. Furthermore,
The phase formed by this rapid cooling must be able to change into a crystalline structure at a low temperature by heating at a predetermined temperature.

(Non-bulk and manufacturing method thereof) In order to obtain reflectance variability, the alloy of the present invention must be capable of forming an appropriately cooled phase by heating and rapidly cooling the material. In order to create and store information at high speed, it is desirable to use a non-bulk material with a high rapid heating and cooling effect and a small heat capacity. In other words, it is desirable that the material be a non-bulk material that has the ability to change substantially only a desired area portion over the entire depth into a crystal structure different from the standard crystal structure by energy input to a desired minute area. Therefore, in order to produce high-density information in a desired minute area, non-bulk materials such as foils, films, thin wires, or powders with low heat capacity are desirable. The recording density is 0.01 to 0.2 μm for producing information in a micro area with a recording density of 20 megabits/d or more.
It is preferable to set the film thickness to . Generally, intermetallic compounds are difficult to plastically work.

Therefore, the PVD method (
It is made of a material that has high heat and low source properties by using vapor deposition, sputtering, etc.), CVD method, and high-speed rotation of molten metal. In particular, there are molten metal quenching methods in which molten metal is poured onto the circumferential surface of a metal roll and rapidly solidified, electroplating methods, chemical plating methods, and the like. When using a film or powder material, it is effective to form it directly on the substrate or to apply it and adhere it to the substrate. When applying,
A binder that does not cause any reaction even when the powder is heated is preferable. Furthermore, in order to prevent oxidation of the material due to heating, it is also effective to coat the surface of the material, the film formed on the substrate, or the surface of the coating layer.

The foil or thin wire is preferably formed by a molten metal quenching method, and preferably has a thickness or diameter of 0.1 m or less.

In particular, 0.051! A thickness or diameter of I11 or less is preferred.

The powder is preferably formed by the Gaia atomization method in which molten metal is sprayed with a gaseous or liquid refrigerant and then poured into water to be rapidly cooled.The particle size is preferably 0.1 rM or less, particularly 1 μm or less. Ultrafine powder is preferred.

The film can be formed by vapor deposition, sputtering, CVD electroplating, chemical plating, etc., as described above.

In particular, sputtering is preferable to form a film with a thickness of 0.1 .mu.m or less; sputtering allows easy control of the target alloy composition.

(Structure) The alloy of the present invention must have a different crystal structure at high and low temperatures, and must have a composition of a supercooled phase in which the crystal structure at high temperature is maintained at low temperature by rapid cooling from high temperature. It has a regular lattice crystal structure, but
The supercooled phase is preferably an intermetallic compound having a C5-CQ type or DO1 type ordered lattice, for example. As the alloy of the present invention is capable of greatly changing optical properties, it is preferable that the alloy mainly forms this intermetallic compound, and a composition in which the entire alloy forms an intermetallic compound is particularly preferable. This intermetallic compound is called an electronic compound, and those having an alloy composition close to a 3/2 electron compound (average outer shell electron concentration e/a of 372) are particularly good.

Further, the alloy of the present invention preferably has an alloy composition having an in-phase transformation, particularly an eutectoid transformation, and an alloy having a large difference in spectral reflectance can be obtained by quenching from a high temperature and non-quenching.

The alloy of the present invention is preferably an alloy having ultrafine crystal grains, and the crystal grain size is particularly preferably 0.1 μm or less.

That is, the crystal grains are preferably smaller than the wavelength of visible light, but may be smaller than the wavelength of semiconductor laser light.

(Characteristics) The variable spectral reflectance alloy and recording material of the present invention can form at least two types of spectral reflectance in the visible light region at the same temperature. That is, it is necessary that the spectral reflectance of a material having a crystal structure (set m>) formed by rapid cooling from a high temperature is different from that of a material having a crystal structure (texture) formed by non-quenching.

In addition, the difference in spectral reflectance obtained by quenching and non-quenching is preferably 5% or more, particularly preferably 10% or more.0 If the difference in spectral reflectance is large, it is easy to visually identify the color, It has remarkable effects in various applications described later.

As a light source for spectrally reflecting, electromagnetic waves other than visible light can be used, and infrared rays, ultraviolet rays, etc. can also be used.

Other properties of the alloy of the present invention include electrical resistivity, optical refractive index, optical polarization rate, optical transmittance, etc., which can be changed reversibly in the same way as spectral reflectance.
It can be used as a regeneration and detection means for sensors, etc.

Since the spectral reflectance is related to the surface roughness of the alloy, it is preferable that at least the intended portion has a mirror surface so as to have 10% or more in the visible light region as described above.

(Applications) The alloy of the present invention can be heated and rapidly cooled to partially or entirely change its physical or electrical properties such as spectral reflectance of electromagnetic waves, electrical resistivity, refractive index, polarization index, and transmittance due to a change in crystal structure. By utilizing changes in these characteristics, it can be used for devices such as recording, display, and sensors.

Electric energy in the form of voltage and current, electromagnetic waves (visible light, radiant heat) are used as a means of recording information, etc.

Infrared rays, ultraviolet rays, photographic flash lamp light, electron beams,
A proton beam, a laser beam such as an argon laser, a semiconductor laser, heat, etc.) can be used, and it is particularly preferable to utilize the change in spectral reflectance caused by the irradiation in the recording medium of an optical disk. Optical discs include digital audio discs (DAD or compact discs), video discs, memory discs, etc. By using the alloy of the present invention in the recording medium of optical discs, playback-only type and additional recording type can be created. .

It can be used in any rewritable disk device, and is particularly effective in rewritable disk devices.

An example of the principle of recording and reproduction when the alloy of the present invention is used in a recording medium of an optical disk is as follows.

First, the recording medium is locally heated and then rapidly cooled to maintain the crystal structure in the high temperature region in the low temperature region to record predetermined information, or the high temperature phase is used as a base to locally heat the recording medium. recorded locally by a low temperature phase during the high temperature phase,
Information can be reproduced by irradiating the recorded portion with light and detecting the difference in optical characteristics between the heated portion and the non-heated portion. Furthermore, the recorded information can be erased by heating the portion recorded as information at a temperature lower or higher than the heating temperature at the time of recording. The light is preferably a laser beam, and a short wavelength laser is particularly preferable. Since the reflectance of the heated portion and non-heated portion of the present invention is greatest at a wavelength around 500 nm or 800 nm, a laser beam having such a wavelength may be used for reproduction. It is preferable to use It is preferable that the same laser source be used for recording and reproducing, and for erasing, a different laser beam having a lower energy density than that for recording is irradiated.

Further, a disk using the alloy of the present invention as a recording medium has a great advantage in that it can be visually determined whether information is recorded or not.

As a display, it is possible to partially change the spectral reflectance of visible light, so it is possible to record characters, figures, symbols, etc. without using paint, and these displays can be visually identified. . Furthermore, this information can be erased, and in addition to being used repeatedly by recording and erasing, it is also possible to store it permanently. Examples of its applications include clock faces and accessories.

As a sensor, there is a temperature sensor that utilizes changes in spectral reflectance, especially in visible light. A sensor using the alloy of the present invention, whose temperature at which it changes to a high-temperature phase is known in advance, is held in the temperature range to be measured.

Approximate temperature detection can be performed by maintaining an appropriate cooling phase through appropriate cooling.

(Production method) The present invention provides a first temperature higher than room temperature in a solid state and a first temperature higher than room temperature in a solid state.
A part of the surface of the alloy having the chemical composition described above, which has a crystal structure different from that at the second temperature lower than the temperature, is rapidly cooled from the first temperature to form a crystal structure different from the crystal structure at the second temperature. and forming a region having a crystal structure formed by the rapid cooling and forming a different spectral reflectance between the region having the crystal structure formed by the rapid cooling and the region having the crystal structure at the second temperature. It is in the manufacturing method of the alloy.

Furthermore, the present invention provides a method for applying the first temperature to the entire surface of the alloy having the chemical composition described above, which has a different crystal structure at a first temperature higher than room temperature and a second temperature lower than the first temperature in a solid state. to form a crystal structure different from the crystal structure at the second temperature, and then heat a portion of the alloy surface to the second temperature to form a region having the crystal structure at the second temperature. and forming different spectral reflectances in the region having the crystal structure formed by the rapid cooling and the region having the crystal structure at the second temperature. be.

The cooling rate from the first temperature is 102° C./second or more.

More preferably, it is 103° C./second or higher.

[Embodiments of the invention]

(Example 1) A Cu-14wt%AQ-5wt%Mn alloy is made into a molten state, and the molten metal is poured onto the outer periphery of a roll rotating at high speed and rapidly cooled, which is the so-called liquid quenching method, to about 40 μm.
A thick ribbon-like foil was produced.

This ribbon was purple at room temperature. This ribbon is 350
When heated to 211 in.℃ and air cooled, it turned white to yellow (Cu
-The AQ binary alloy has a golden yellow color compared to the red copper color, but the Mn
When it contains, it changes to purple, white and yellow.

), and when this ribbon was further heated at 750°C and cooled with water, its color changed to purple. When these color tone changes are organized in terms of the relationship between heating time and temperature, the results are shown in FIG. That is, the color is intermediate between purple and white-yellow at 200-300°C, white-yellow at 350-700°C, and purple at 750°C or higher. This does not change much depending on the heating time; when the foil that has become white-yellow in this way is heated to 750°C or higher, it becomes purple, and the foil that has become purple is heated to 700°C.
When heated below, it returns to white-yellow color. A reversible tone memory effect thus occurs between these two colors. The above color tone change had a similar tendency in all cases in the composition range of the present invention other than the above-mentioned alloys. The third time is the result of measuring the spectral reflectance of both of these. Each exhibited a unique reflectance change and could be identified in the wavelength range except around 450 nm. Thereafter, even if these two heating and quenching processes were repeated, this difference hardly changed, and the reproducibility of the reversible change was confirmed.

(Example 2) A 50 nm thick alloy thin film having the same composition as in Example 1 was produced on a glass substrate by sputter deposition, and a protective film of An, O, or Sin was coated thereon to a thickness of 50 nm by sputter deposition. The membrane prepared under this condition exhibited a purple color. Then, this film was heated at 350° C.2Ilin and air cooled, resulting in a change in color to white-yellow.

This spectral reflectance was almost the same as the result shown in FIG. A spot diameter of approximately 2 μm is applied to a sample where the entire surface of the membrane has turned white and yellow.
A semiconductor laser was scanned with an output of 30 mW or less. Observation of the laser irradiation area at room temperature revealed a white-yellow base with a width of approximately 2 μm.
I found that I was able to draw a purple line of m. That is, it was confirmed that the color could be changed by local heating with laser light, and that laser irradiation could be recorded as a color change.

Next, by lowering the laser output or slightly shifting the focus of the laser light from the film surface, irradiate the discolored area with laser light, and the line part that changed to purple will reversibly change to the white-yellow color of the base. changed. In other words, it was confirmed that what was recorded in purple could be erased. It was also confirmed that this reversible change is possible even if it is repeated thereafter.

It was confirmed that the above results can also be obtained using an Ar laser.

(Example 3) A semiconductor laser (output 20 mW) was scanned on a sample prepared in the same manner as in Example 2, that is, a sample whose entire surface was purple at room temperature. The laser scanning part turned white-yellow at room temperature and could be distinguished from the base color.

In other words, laser recording was possible. After that, the whole 3
When heated to 50℃ for 2wins, the whole turns white-yellow,
I was able to erase the recorded part.

The above results could also be achieved using an Ar laser.

[Effects of the Invention] The present invention is a recording material that can be recorded and erased based on a crystal-crystalline phase change using light or thermal energy, and has
The output level is high and stable.

[Brief explanation of drawings]

Figure 1 is a binary alloy phase diagram schematically showing changes in crystal structure due to phase transformation of Cu-An alloy, and Figure 2 is C
FIG. 3 is a diagram showing the change in color tone of the u-14Alt-5Mn alloy as a function of temperature; FIG. 3 is a diagram showing the spectral reflectance of the Cu 15AA-5Mn alloy foil used as a recording material.

Claims (1)

[Scope of Claims] 1. A variable spectral reflectance alloy comprising copper as a main component and containing 14 to 16.5% by weight of aluminum and 0.01 to 15.0% by weight of manganese. 2. A part of the alloy surface having a different crystal structure at a first temperature higher than room temperature and a second temperature lower than the first temperature in the solid state is formed by rapid cooling from the first temperature. having a crystal structure different from the crystal structure at the second temperature,
2. The variable spectral reflectance alloy according to claim 1, wherein the other alloy has a crystal structure at the second temperature and has a spectral reflectance different from that of the rapidly cooled crystal structure. 3. The variable spectral reflectance alloy according to claim 1 or 2, wherein the alloy contains an intermetallic compound. 4. The variable spectral reflectance alloy according to any one of claims 1 to 3, wherein the first temperature is higher than the solid phase transformation point. 5. A patent claim in which the difference between the spectral reflectance of a product having a crystal structure formed by the rapid cooling and the spectral reflectance of a product having a crystal structure at the low temperature formed by non-quenching is 5% or more. The variable spectral reflectance alloy according to any one of the ranges 1 to 4. 6. The spectral reflectance of the alloy is at a wavelength of 400 to 1000 nm.
10% or more of the variable spectral reflectance alloy according to any one of claims 1 to 5. 7. Claim 1, wherein the alloy is a non-bulk material.
The variable spectral reflectance alloy according to any one of items 6 to 6. 8. The variable spectral reflectance alloy according to any one of claims 1 to 7, wherein the alloy has a crystal grain size of 0.1 μm or less. 9. The variable spectral reflectance alloy according to any one of claims 1 to 8, wherein the alloy is any one of a thin film, foil, strip, powder, and thin wire. 10. A recording material comprising an alloy containing copper as a main component, 14 to 16.5% by weight of aluminum, and 0.01 to 15.0% by weight of manganese. 11. An alloy having different crystal structures in a solid state at a first temperature higher than room temperature and a second temperature lower than the first temperature, wherein at least a part of the alloy surface is at the first temperature. 11. The recording material according to claim 10, having an alloy composition that forms a crystal structure different from the crystal structure at the second temperature when quenched from the recording material. 12. The recording material according to claim 10 or 11, which is a foil or thin wire formed by pouring the molten metal of the alloy onto the circumferential surface of a rotating roll made of a highly thermally conductive member. 13. Claim 10 or 11, which is a thin film formed by depositing the alloy by vapor deposition or sputtering.
Recording materials listed in section. 14. The recording material according to claim 10 or 11, which is a powder obtained by spraying the molten metal of the alloy using a liquid or gas cooling medium.