JPS61133350A - Alloy capable of varying spectral reflectance and recording material - Google Patents

Abstract

PURPOSE:To offer the titled alloy capable of holding spectral reflectances different partially at the same temp., by composing it of alloy contg. Ag as main constituent and specified compsn. quantities of Al, groups Ia, IIa, IVa, VIIa, VIII, Ib-Vb and rare earth element, etc. CONSTITUTION:The titled alloy is composed of alloy contg. Ag as main component, 6-10wt% Al, <=15% total of >=one kind among groups Ia, IIa, IVa, Va, VIa, VIIa, VIII, Ib-Vb of the periodic table, and rare earth element. To a part of alloy having said chemical composn. and different crystal structures at the first higher temp. than room temp., and the second lower temp. than the first temp. in solid state, crystal structure different from that at said second temp. and different spectral reflectance are formed by rapid cooling from the first temp. to obtain the titled alloy. By said thermal energy, alloy having spectral reflectance capable of being varied due to crystal phase variation is used as recording material favorably by utilizing the characteristic.

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 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 Metals & 80.1983 (Optical Disks and Materials), and are expected to become more promising in the future. It is a powerful method of 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 allows writing only once and cannot be erased, while the latter allows repeated writing 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 Tθ or its alloy is used to form irregularities by melting and sublimating it. This type of 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. but.

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, there is a big problem that output levels such as S/N and C/N are low. Other rewritable systems utilize changes in reflectance due to reversible phase changes between amorphous and crystalline recording media.For example, National Technical Report
There is an alloy in which small amounts of Ge and Sn are added to TaOx, which is described in Vol. 129 k 5 (1983).

However, this method has a major problem in that the crystallized portion 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 one color tone change, JP-A-57-1
There are 40845. This alloy is (12-15)wt%A
n-(1-5) wt% Ni-remaining Cu alloy with martensitic transformation temperature as the boundary.

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 the martensitic transformation temperature is lowered to a temperature below 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 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 a main component, aluminum (AQ) 6 to 10% by weight, and Ia, I[a].

The variable spectral reflectance alloy is characterized by comprising an alloy containing a total of 15% or less of one or more of IVayVa*VIa+a, Ib-Vb, and rare earth elements.

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 is heated and cooled in a solid state.

It has at least two types of spectral reflectance at the same temperature.

This allows the spectral reflectance to be changed reversibly.

That is, the alloy according to the present invention has at least two
It has phases with different crystal structures in two temperature regions, and among them, the spectral reflectance is different between the quenched state of the high temperature phase and the low temperature phase state of the non-quenched standard state. The spectral reflectance changes reversibly by heating and cooling in the low phase temperature region. Also, by using this change, information such as signals, 2 characters, 2 figures, symbols, etc. can be recorded and reproduced.

It can be erased and is extremely effective as a recording material.

The principle of reversible change in reflectance of the alloy of the present invention will be explained with reference to FIG. FIG. 1 shows an equilibrium phase diagram of the Ag-AQ binary alloy.

The second principle describes the principle of recording and erasing signals such as nine characters and two figures as information by utilizing changes in the crystal structure associated with phase transformation of alloys.
This will be explained using figures. In the alloy of composition CI) in the figure,
There are three phase states in the solid state. i.e. β single phase, ζ
There are two phases: phase and μ+ζ phase.

The crystal structure differs between β and μ, each of these single phase states,
Therefore, although it is natural for these to be used alone, their optical properties also change depending on the mixed phase. Spectral reflectance will be explained as a difference in optical properties due to a difference in crystal structure. T1 means the temperature at which what is recorded can be read, and can be considered to be room temperature. In the equilibrium state of T1, it is μmrichμ+ζ phase, so the spectral reflectance of the alloy is μ
Close to.

When this is heated to T2 and rapidly cooled, the ζ phase is maintained at T□. The spectral reflectance of the ζ phase at T1 is different from that of the μ+ζ phase. Therefore, both phases can be distinguished. Also,
The same thing can be said when heating and rapidly cooling down to T1 temperature. That is, the general color tone characteristics that can be distinguished as β phase and μ+ when β is maintained at T,'1:A degree by rapid cooling are as follows.

The ζ phase at T□ when the temperature is maintained and then rapidly cooled is pale golden yellow, and the μ+ζ phase is silvery white. That is, by irradiating the alloy in the μ+ζ phase state with a laser beam having a diameter of, for example, several μm, the alloy is locally T,
After heating to 100%, stop laser irradiation. The irradiated part is rapidly cooled, and only the laser irradiated part becomes the ζ phase. Since the portion that is not irradiated with the laser remains in the μ+ζ phase, at T1, the spectral reflectance of the laser irradiated portion differs from that of the other portions, and the two can be distinguished. This state corresponds to the recording state. On the other hand, if the material is heated to T8 and then rapidly cooled and heated to T1, which is higher than T8, the β phase changes to μ + ζ phase, and even if the temperature is returned to T1, μ
It remains in +ζ phase. Therefore, as mentioned above, a laser beam is irradiated to the part that has been locally made into the ζ phase by laser irradiation, and T2
When heated to a temperature of , the ζ phase changes to the μ+ζ phase. After that, even if the temperature is returned to T, the μ+ζ phase state is maintained.

In other words, this corresponds to erasure. Note that in order to change the ζ phase to the μ+ζ phase, it is sufficient to heat it to a temperature higher than T1, but the upper limit temperature is Te1 in Figure 1, and the process of temperature 6 or higher can be repeated. , it can be applied as a so-called rewritable recording medium.

The above also applies to the case of heating and quenching to T3 temperature. Therefore, recording and erasing is possible between the β and μ+ζ phases.

Another recording method uses a sample in the β phase state at temperature T1. For example, by irradiating this with a laser beam with a diameter of several μm, T1
When heated to ', the laser irradiated part changes to μ+ζ phase.

Even after cooling to a temperature of T1, the laser irradiated part is in the μ+ζ phase, which can be distinguished from the phase in the non-laser irradiated part 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 ζ phase at the temperature T1.

(Alloy Composition) The alloy of the present invention must have different crystal structures at high and low temperatures, and the rapidly cooled crystal structure must be formed by rapid cooling from the high temperature β phase; The phase formed by rapid cooling must change to the crystalline structure at low temperature by heating at a predetermined temperature, so AQ is 6-10% by weight and la.

Uag ■at Va, Vlat■a, ■, Ib-Vb
.

The total amount of one or more rare earth elements is 15% by weight or less. Specifically, the LA group is Li, the LA group is Mg, and C.
a, Il/a group is Ti, Zr, Hf.

Va group is V, Nb, Ta, ■a group is Cr, Mo
.

W, ■A group is Mn, ■group is Cot Rh, It'.

Fe, Ru, Os+ Ni, Pd, Pt, I b group is C
U, Au, mb group is Zn, Cd, mb group is B.

G a y I n , IV b group is C, Sit Ge
, Sn.

Pb and Vb groups are P+Sb, Bi, and rare earth elements are Y.

La, Co, Sm+Gd+Tb, D7e Lu are preferred, particularly preferably 0.1 to 5% by weight. These elements have a temperature at which they transform from β′ to ζ phase (Ti
,.

lower. This has the effect of lowering the heating temperature when erasing recorded information.

(Non-bulk production 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 to be a non-bulk material having a volume that allows substantially only a desired area portion to change to a crystal structure different from the standard crystal structure throughout the depth by energy input to a desired minute area. 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.
Generally, intermetallic compounds are difficult to plastically work.

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 a PVD method (vapor deposition, sputtering method, etc.), a CVD method, and a member having high thermal conductivity that rotates the 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 film or powder materials, either form them directly on the substrate or! ! l
It is effective to apply a cloth and adhere it onto the substrate. When coating, it is best to use a binder that does not cause a reaction even when the powder is heated.Also, to prevent oxidation of the material due to heating, it is also possible to coat the surface of the material, the film formed on the substrate, or the surface of the coating layer. It is valid.

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, for producing foils or thin wires with a grain size of 0.1 μm or less, a thickness or diameter of 0.05 am or less is preferred b).

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 nm 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, and sputtering allows easy control of the target alloy composition.

It is also effective to divide the film to the same extent as the memory unit by chemical etching.

(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
For example, the supercooled phase is preferably an intermetallic compound having a C5-CQ type or DO3 type ordered lattice, and the alloy of the present invention is an alloy that mainly forms this intermetallic compound as it can greatly change the optical properties. is preferred, and particularly preferred is a composition in which the entire alloy forms an intermetallic compound. 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 in-phase 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 preferably has ultrafine crystal grains, and the 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 (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.
l again. The difference in spectral reflectance obtained by quenching and non-quenching is preferably 5% or more, particularly preferably 10% or more. 6. If the difference in spectral reflectance is large, it will be easy to visually identify the color, and later. It has remarkable effects in the various applications described.

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, displays, etc. By using the alloy of the present invention in the recording medium of optical discs, playback-only type, additional It can be used for both recordable and rewritable disk devices, 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 locally heated as a base. 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.1 Since the reflectance between the heated part and the non-heated part of the present invention is greatest at a wavelength around 500 nm or 800 nm, a laser beam having such a wavelength is used for reproduction. Preferably, the same laser source is used for recording and reproduction.

For erasing, it is preferable to irradiate another laser beam with a lower energy density than that for recording.

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. 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 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 preferably 102° C./second or more, more preferably 103° C./second or more.

[Embodiments of the invention]

(Example 1) Ag-7, 5 wt% Al, Ti, Ta, Cr.

An alloy to which 2% by weight of Znp In, Sb, and La were individually added was melted in a vacuum high-frequency induction furnace to form an ingot. This ingot was golden in color. A ribbon-shaped foil was produced by melting this ingot and rapidly cooling the molten metal on the surface of a single roll rotating at high speed or between multiple rolls. The former is a Cu roll with a diameter of 300 m (the surface is C
r plating).

The latter was a Cu-Ba1l roll with a diameter of 120 cm, and the peripheral speed of the roll was set at 10 to 20 m/s. A quartz nozzle was used to melt the mother alloy, and approximately 10 g per charge was melted and rapidly cooled to a thickness of 5 mm and a thickness of 40 μm.

A ribbon wipe several meters in length was prepared. The color tone of this ribbon at room temperature was pale golden yellow. 210 parts of this thing
When heated at ℃ for 1 minute, it showed a silvery white color at room temperature. Spectral reflectance was measured for these color tones.

A difference of approximately 15% was observed between light golden yellow and silvery white where the spectral reflectance was high. Therefore, both can be distinguished by color. All of these colors can be stored permanently at room temperature. Furthermore,
This shows that it is possible to store information such as signals, characters, symbols, etc. in pale golden yellow on the silver-white base by local heating with a laser. Furthermore, it is possible to record information such as signals using silvery white on the opposite light golden base.

(Example 2) A reversible change in color tone was confirmed in a thin film produced by sputter deposition. Diameter L from the ingot produced in Example 1
A disk with a thickness of 5 m was cut out and used as a target for a sputtering device. A glass plate (
A thickness of 0.8+m) was used. Heating oxidation during writing and erasing sputtered films.

To prevent peeling from the substrate, the surface is coated with Sin,
Protection 1! A DC-magnetron type was used for the evaporation of the 1 alloy film formed by evaporation of J (thickness: 30 nm), and a SiO
□ An RF type sputtering method was used for each film. The sputtering output was set to 140 to 200 W, and the substrate temperature was set to room temperature. After the inside of the container was evacuated to about 10-' Torr, Ar gas was introduced at 5 to 30 mTorr to form a thin film. The film thickness was Sin, the film was about 30 nm, and the alloy films were made with various thicknesses from 0.05 to 10 μm.
The crystal grains of the film (thickness: 300 nm) are ultra-fine, and the diameter of one grain is approximately 3
It is ultra-fine at 0 nm, and it is thought that there is no influence of crystal grains on recording, reproduction, and erasing. The as-deposited alloy film was pale golden yellow.

Several alloy films prepared by sputtering were heated at 210°C for 1 minute to turn silvery white, and then Ar
The mAr laser, which performs writing and erasing using laser heating and cooling, is a continuous wave laser. Place the sample on the manual translation stage.

The sample was moved and the laser beam was focused and scanned on the film surface. The part irradiated with the laser light turns pale golden yellow,
The same applies to the 0-dot line portion written like a diagonal line. The writing is a trace of scanning with a 200 mW Ar laser beam with a spot diameter of 10 μm.

The alloy film was heat-treated to give it a silvery white color in advance for each substrate, and the focus of the primary laser beam was slightly shifted from the film surface, and the laser output density was lowered to scan. Result 1
The original light golden color was erased and changed to silvery white. From the above results, it was confirmed that recording and erasing by changing the color tone is possible even in a thin film state of the alloy. It has been confirmed that this writing and erasing can be repeated any number of times.

At room temperature, A
! - Set the laser output to about 50mW.

The 1-Ar laser scanning section turned silvery white at room temperature and could be distinguished from the light golden color of the base, indicating that recording was possible.

Thereafter, when the whole was heated to 210° C. for 1 win, the light golden yellow portion changed to silvery white, and at room temperature the entire surface was silvery white, indicating that it could be erased.

(Example 3) The ingot produced in Example 1 was made into powder and its color change was examined. After mechanically cutting the ingot, the chips were crushed. Since the ingot is brittle, it becomes a fairly fine powder with chopped charcoal, but this was further crushed to about 1,100 meshes. In the as-pulverized state, the color was silvery white, but when it was heated at 450° C. for 1 minute and then cooled with water, it was confirmed that it changed to a light golden color.

Furthermore, the powder pulverized from the ingot is made into powder with a particle size of several micrometers using a ball mill, mixed with an organic material, coated on a glass substrate, and fired in a non-oxidizing atmosphere to form a powder with a particle size of approximately 100 micrometers.
An alloy film with a thickness of .

A Sin film with a thickness of about 30 nm was formed on the surface of this alloy film by vapor deposition. The glass substrate was mirror-polished, and after the alloy film was formed, it was mirror-polished in the same way. The alloy film as it is formed has a silvery white color, but it was confirmed that it changes to a pale golden yellow by irradiating it with laser light at a temperature that transforms into another phase, as described above.

〔Effect of the invention〕

The present invention provides an alloy whose spectral reflectance is variable based on a crystal-to-crystalline phase change caused by thermal energy such as light.

[Brief explanation of drawings]

Figure 1 is a schematic binary alloy phase diagram showing changes in crystal structure due to phase transformation of Ag-AQ alloy, and Figure 2 is a diagram showing the principle of recording and erasing information using the alloy of the present invention. . ', N'' L No. 1 Hitachi, Ltd. Hitachi Research = 97Q-

Claims (1)

[Claims] 1. Mainly composed of silver, 6 to 10% aluminum by weight, and Ia, IIa, IVa, Va, VIa, VIIa of the periodic table,
A variable spectral reflectance alloy comprising an alloy containing a total of 15% or less of one or more of VIII, Ib to Vb, and rare earth elements. 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. Main component is silver, 6-10% aluminum by weight
and I a, IIa, IVa, Va, VIa, VIIa, VIII,
I b to Vb, one or more rare earth elements in total 1
A recording material comprising an alloy containing 5% or less. 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.