JPS61110736A - Spectral reflection factor variable alloy and recording material - Google Patents

Abstract

PURPOSE:To obtain a titled alloy for holding a partially different spectral reflection factor at the same temperature, which consists of silver as a main component, and contains zinc and copper of a specified quantity. CONSTITUTION:A titled spectral reflection factor variable alloy consists of silver as a main component, and also an alloy containing 30-46wt% Zn and 0.5-2.0% Cu, and one part of the alloy surface having a different crystal structure at the first temperature being higher than a room temperature in a solid state and at the second temperature being lower than and temperature has a crystal structure different from a crystal structure at said second temperature by quenching from said first temperature, and the other part has a crystal structure at said second temperature and also has a spectral reflection factor being different from that of said quenched crystal structure. Said alloy is used as a recording material by utilizing a variation of a spectral reflection factor caused by a variation of a crystal structure due to a fact that light/heat energy is given.

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 to a spectral reflectance variable alloy due to changes in the crystal structure of a υ alloy due to the application of light and thermal energy. The present invention relates to an alloy that can be used as a medium for information recording, display, sensors, etc. using changes in reflectance.

[Background of the invention]

In recent years, as the density of information recording has increased and digitalization has progressed, various information recording and reproducing methods have been developed. In particular, optical disks that use laser light energy to record, erase, and reproduce information are capable of higher recording densities than magnetic disks, as stated in Industrial Rare Metal 80, 1983 (Optical Disks and Materials), and are expected to have higher recording densities in the future. This is a powerful method for recording information. Among these, laser playback devices have been put into practical use as compact discs (CDs). 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 for recording and erasing of data.

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 V-za 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 feeding medium has some problems such as toxicity. Magneto-optical materials are the mainstream for rewritable recording media.

This method utilizes optical energy to invert and record the local magnetic anisotropy of the medium near the Curie point or compensation point temperature, and the polarization plane of the polarized incident light at that part due to 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, at present, there is no material with a large amount of rotation of the plane of polarization, and even with various efforts such as multilayer film formation, the C/N is 87N, C/N
A major problem is that the output level is low. Other rewritable systems utilize reflectance changes due to reversible phase changes between amorphous and crystalline recording media. For example, National Technical f
i,eport Vo! , 29 A 5 (1983
There is an alloy in which a small amount of Ge and Sn are completely added to TeOx described in 1.

However, this method has a major problem in that the crystallization rate 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
This is an alloy consisting of t-(1-5)wtesNi-residual Cu, which takes advantage of the fact that it changes reversibly from red to gold at the martensitic transformation temperature. Martensitic transformation is a transformation that inevitably occurs as the temperature decreases, so the color tone obtained when the temperature is maintained above the martensitic transformation temperature cannot be brought below the martensitic modulation temperature. Conversely, if a color tone obtained at a temperature below the martensitic transformation temperature is heated above the martensitic transformation temperature, the color tone will undergo transformation and change to a different color tone. Therefore, the two color tones occurring above and below the martensitic transformation cannot be obtained at the same time at the same degree. Therefore, this 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 the Invention) The present invention contains silver (Ag) as the main component and zinc (Zn) by weight.
The variable spectral reflectance alloy is characterized by comprising an alloy containing 130 to 46% copper and 0.5 to z04 copper.

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

The alloy of the present invention has at least two types of spectral reflectance at the same temperature by heating and cooling treatment in a solid state, and the spectral reflectance can be changed reversibly. That is, the alloy according to the present invention has phases with different crystal structures in at least two temperature ranges in a solid state, and among these, the high temperature phase is quenched and the low temperature phase is a non-quenched standard state. Although the spectral reflectance is different, the spectral reflectance changes reversibly by heating and cooling in the high phase temperature region and 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.

FIG. 1(a) shows a schematic equilibrium state diagram of an Ag-Zn binary alloy, and is a signal as information.

The principle of recording and erasing characters, figures, etc. will be explained with reference to FIG. 1(b). Let us take as an example an alloy having composition CI) in FIG. 1(a). ``This alloy is in the ζ phase at equilibrium.

The color of this phase is silvery white, and a corresponding curve is obtained in the spectral reflectance. This alloy has a high temperature phase β
When rapidly cooled after heating to the phase stable temperature region (T4), the β phase cools down appropriately and becomes a β' phase with a regularized crystal structure.

The color tone of the alloy in this moderately cooled state is pink) and the spectral reflectance is also significantly different from that in the ζ phase state. When this alloy is heated in the ζ phase stability temperature range (T, below) (T2), β' transforms into the ζ phase, and the color tone of the alloy changes reversibly from pink to silvery white, and the spectral reflectance also changes to its original state. Return to From now on, this past
Can be repeated. The key point of the present invention is a material in which the above color tone change is applied to recording, reproducing, and erasing information. In other words, it can be used as a recording medium by utilizing changes in reflectance and color tone due to phase transition of different crystal correlations.

Regeneration is at TI humidity and temperature, generally at room temperature.

At T1, energy is selectively applied to the silver-white material in the ζ phase, heated to T4, and then rapidly cooled. Then, that part becomes β' phase and changes color to pink. This corresponds to a record. The recorded portion can be reproduced by comparing this portion with other portions. By applying a different density of energy to this pink colored part and heating and cooling it to T2, the phase transforms from β' to ζ and returns to silvery white. This corresponds to erasing records. The above-mentioned recording, reproducing and erasing processes can also be performed by completely opposite color tone changes. That is, β
The pink color of the ′ phase is recorded as a silvery white color by utilizing the β′ → ζ transformation. This is reproduced in distinction from t-pink. Further ζ
It can be eliminated by changing the phase to β' phase.

Generally, electromagnetic waves are suitable as the above-mentioned energy. Specifically, various laser beams, electron beams, etc. are also suitable. For reproduction, light of any wavelength that shows a difference in spectral reflectance may be used.

That is, lasers, lamps, etc. in the ultraviolet to infrared region are suitable. Furthermore, since it can be recognized as a change in color, it can also be used as a display element.

From the above points of view, the preferred composition is 3, in which the high-temperature β phase cools down appropriately.
The range is 0 to 46wt4Zn and 0.5 to 2.0wt11iCu. Cu lowers the transformation temperature (T, ) of the β and ζ phases. This has the effect of lowering the heating temperature during recording. Effective recording and erasing by heating and quenching can be achieved by reducing the heat capacity of the medium.

(Non-bulk and manufacturing method thereof) In order to obtain reflectance variability, the alloy of the present invention must be able to form a supercooled 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. That is, it is desirable to be a non-bulk material having a volume in which substantially only a desired area portion can be changed to a crystal structure different from the standard crystal structure over the entire depth 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 0101 to 0.2 μm for producing information in a micro area with a recording density of 20 megabeats/- or more.
It is preferable to set the film thickness to . In general, intermetallic compounds are difficult to greasy process. Therefore, it is effective to directly rapidly cool and solidify the material from the gas phase or liquid phase to form it into a predetermined shape as a method for producing foil, film, thin wire, or powder. These methods include PVD methods (vapor deposition, sputtering methods, etc.).

CVD method, consisting of a member with high thermal conductivity that rotates molten metal at high speed. 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 preferred. Furthermore, in order to prevent oxidation of the material due to heating, it is also effective to coat the surface of the material, a film formed on the substrate, or the surface of the coating layer with kSi 02 , kLtos, or the like.

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

In particular, in order to produce foil or thin wire with a crystal grain size of 1 μm or less, a thickness or diameter of 0.05 W or less is preferable.

The powder is preferably formed by a Gaia atomization method in which molten metal is atomized together with a gaseous or liquid refrigerant and then poured into water to be rapidly cooled. The particle size is preferably 0.1 W or less, and ultrafine powder with a particle size of 1 μm or less is particularly preferable.

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 μm or less. Sputtering allows easy control of the target alloy composition.

It is also effective to separate the film (by chemical etching) to the same degree as the memory unit.

(Structure) The alloy of the present invention has different crystal structures at high and low temperatures, and must have a composition of an undercooled phase that maintains the crystal structure at high temperature at low temperature by rapid cooling from high temperature. At high temperatures, it has an irregular lattice crystal structure, but
The supercooled phase is preferably an intermetallic compound having a C5-CL type or D On type regular 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 3/2) are particularly good.

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

The alloy of the present invention preferably has ultrafine crystal grains, and particularly preferably has a crystal grain size of 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 (structure) formed by rapid cooling from a high temperature is different from that of a material having a crystal structure (structure) formed by non-quenching.

Further, the difference in spectral reflectance obtained by quenching and non-quenching is preferably 5 or more, particularly preferably 10 or more. If the difference in spectral reflectance is large, it will be easy to visually distinguish colors, and this will have a significant effect in various uses described later.

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

Other properties of the alloy of the present invention include electrical resistivity.

The refractive index of light, the polarization index of light, the transmittance of light, etc. can be changed reversibly in the same way as the spectral reflectance, and various information can be recorded5.
It can be used as a means of display, reproduction of sensors, etc., and detection means.

Since the spectral reflectance is related to the surface roughness of the alloy, it is preferable that the alloy has a mirror surface at least in the target portion so as to have 1 (1 or more) at least in the visible light region as described above.

(Applications) The alloy of the present invention has a spectral reflectance of electromagnetic waves due to a partial or total change in crystal structure due to heating and rapid cooling.

Physical or electrical properties such as electrical resistivity, refractive index, polarization index, transmittance, etc. can be changed, and changes in these properties can be utilized for use in elements 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 flashlight, laser beams such as laser beams, proton beams, argon lasers, semi-enveloped lasers, heat, etc.) can be used, and in particular, changes in spectral reflectance due to irradiation can be It is preferable to use this as a recording medium for an optical disc. Optical discs include digital audio discs (DAJ) or compact discs),
It can be used for video discs, memory discs, etc. By using the alloy of the present invention in the recording medium of an optical disk, a playback-only type and an additional recording type can be produced.

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 retain the crystal structure in the high temperature region in the low temperature surface region to record predetermined information, or the high temperature phase is used as a base to locally heat the recording medium. recorded by a locally low temperature phase during the antistatic 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 during recording. The light is preferably a laser beam, particularly a short wavelength laser. Since the reflectance between the heated portion and the non-heated portion of the present invention is greatest at a wavelength around 5QQ nm or 800 nm, it is preferable to use a laser beam having such a wavelength for reproduction. 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 in visible light, so characters, figures, symbols, etc. can be recorded without using paint, and these displays can be visually identified. . Furthermore, this information can be erased, and in addition to being used repeatedly for recording and erasing, it is also possible to store it permanently. Examples of its applications include clock faces and aquariums.

As a sensor, there is a temperature sensor that utilizes changes in spectral reflectance, especially in visible light. Approximate temperature detection can be made by holding a sensor using the alloy of the present invention, whose temperature at which it changes to a high temperature phase is known in advance, in the temperature range to be measured, and maintaining the appropriate cool phase by cooling it appropriately.

(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 different crystal structure at a second temperature lower than the temperature of 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 alloy 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 the ambient 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 part 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. It's in the law.

The cooling rate from the first temperature is preferably 10"C/sec or more, more preferably 103 r/sec or more.

[Embodiments of the invention]

[Example 1] An Ag-35wt1GZn-Cu alloy was molded into a foil shape by a molten metal quenching method, and its color tone change, spectral reflectance, etc. It was melted and solidified into a rod shape of about 4Wφ. This material was cut into pieces weighing about 5 to 10 g, and used as a mother alloy for rapidly cooling molten metal.

A commonly known single roll type device was used for the molten metal quenching method. The master alloy was charged into a quartz nozzle, remelted, and poured onto the outer periphery of a highly thermally conductive metal roll (300 wφ) rotating at high speed to produce the above Ag-Zll-Cu alloy foil with a thickness of 50 μm and a width of 5 cm. did. This foil was heated in an electric furnace for 2 minutes at each temperature, then cooled with water, and the color change and spectral reflectance of the foil were measured. Figure 2 shows the color change of the foil after heating and quenching.・The mark is pink and the 0 mark is silvery white. Ag-35% without Cu
7. The boundary of color change in n alloys is approximately 275C, but as the amount of Cu increases, the effect becomes lower. However, when the temperature range is 2 or higher, everything is pink in the temperature range shown in the figure, and it is no longer possible to distinguish between colors. Therefore, the upper limit of Cu amount is 1.81
is preferred.

FIG. 3 shows the color of the pink foil when it was heat-treated at each temperature below 250C for 2 minutes and then air-cooled.

The pink color changes to silvery white below about 200 t:', and the temperature at which this color tone changes increases as the amount of Cu increases. The above color change is caused by the β′ phase, which causes the pink color due to rapid cooling from high temperature, and the change from pink to silvery white is due to the β′ phase.
This is thought to be due to the ′→ζ transformation.

In FIG. 4, significant differences in reflectance are observed except in the 530-6000 m wavelength region, which shows the spectral reflectance of Ag-351Z n-1%Cu. The color change from pink to silvery white as described above reversibly changed by repeating heating and quenching at 240C and 200r, and the spectral reflectance also changed almost reversibly accordingly.

Furthermore, when silver-white foil was locally heated and rapidly cooled with a lighter, only those areas turned pink), and the boundaries between the colors were very clear. Conversely, when the pink foil was locally heated, some parts became silvery white.

[Example 2] An Ag 351Zn-1% Cu alloy was melted in an argon atmosphere and solidified into a cylindrical shape with a diameter of about 120 cm. From this, a disk with a thickness of 5 stages and a diameter of 100+a+φ was cut out and used as a target for sputter deposition.

A DC-magnetron type sputter deposition method was used, and the substrate was a hard glass gold circle with a diameter of about 26 iol and a thickness of 1.2 m, a substrate temperature of 200 C, and a sputter power of 150 m.
The above alloy was sputter-deposited to a thickness of about 8 Qnm under W conditions. The gas used was Ar at 20 mTorr. A protective film of F)A Axis or 5iChk was further deposited on the film surface to a thickness of about 20 nm by R,F sputtering.

In the sputter-deposited state, the film was silvery white. When this substrate was heat treated at 240C for 2 minutes and cooled with water, it turned pink. When this was further heat-treated at 200C under the same conditions, the color returned to silvery white. In this way, the sputtered film also showed the same color change as the foil.

[Example 3] Ag-351Z n- produced by the same method as Example 2
Recording on the 14Cu sputtered film using laser light.

Performed playback and deletion. As a laser beam, a semiconductor laser (wavelength 830 nm) or an Ar laser (wavelength 4881 nm) is used.
m) was used. The power of the laser beam is 10 to 5 Qm on the film surface.
As a result of scanning the silver-white film surface by changing the W and beam diameter from about 1 μm to about 10 μm, a pink-colored line could be drawn. This line width could be varied from about 1 μm to 20 μm depending on the laser output. By arranging several such lines and scanning a semiconductor laser across the lines, it was possible to convert the color change into an electrical signal as a change in DC voltage level of approximately 201 cm due to the change in reflectance.

The lines drawn in this way could be easily restored to their original silvery white color by heating the entire back side to nearly 200C or by scanning with a laser beam of low power density.

〔Effect of the invention〕

According to the present invention, it is possible to reversibly change the color or spectral reflectance due to crystal-crystal phase transition, so that remarkable effects can be obtained as an information recording medium.

[Brief explanation of the drawing]

Figure 1(a) is an equilibrium state diagram of the Ag-Zn binary system, Figure 1(b) is a diagram showing the principle of recording and erasing by the heating and quenching process of the alloy of the present invention, and Figures 2 and 3 are the diagrams of this book. Figure 4 shows the color change due to heat treatment of the invention's bath water quenched Ag-Zn-Cu alloy foil.
240C 2 minutes water cooling → 200C 2 minutes air cooling) A g
-354Z n-1 Agent Patent Attorney Akio Takaran ゛(5 χ 1 Figure (I!lL) Figure 2 Ca (wt %)
/gσx J tnnJinoContinued from page 10 Inventor Yoshimi Kato 3 Saiwai-cho, Hitachi City
゛Inside

Claims (1)

[Scope of Claims] 1. A variable spectral reflectance alloy comprising silver as a main component and containing 30 to 46% zinc and 0.5 to 2.0% copper by weight. 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 9, wherein the alloy is any one of a thin film, foil, strip, powder, and thin wire. 10. A recording material comprising an alloy mainly composed of silver and containing 30 to 46% zinc and 0.5 to 2.0% copper by weight. 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.