JP2012149201A - Thermochromic body and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a vanadium dioxide film comprising a VOphase that is excellent in crystallinity at temperature close to room temperature.SOLUTION: A thermochromic body 1 comprises: a base film 11 consisting of a magnesium oxide film or an oxide film formed by adding zinc to magnesium oxide, wherein the base film is formed on a base substance 10; and the vanadium dioxide film 12 formed on the base film 11.

Description

  The present invention relates to a thermochromic body and a method for producing a thermochromic body, and more particularly to a thermochromic body capable of forming a film at a low temperature and a method for producing a thermochromic body.

  Vanadium dioxide is known as a material exhibiting a thermochromic phenomenon. The thermochromic phenomenon refers to a reversible change in optical characteristics due to a temperature change. Vanadium dioxide undergoes a phase transition from a monoclinic system to a tetragonal rutile structure at about 68 ° C., and the light reflectance in the infrared region greatly increases.

  Attempts have been made to use vanadium dioxide as a heat ray shielding material, focusing on the properties of vanadium dioxide near room temperature. This phase transition is a reversible semiconductor-metal transition, and as described in Patent Document 1 and Patent Document 2, a small amount of tungsten, molybdenum, or the like is added to make the phase transition temperature near room temperature or lower. It is possible to reduce it to

  In recent years, with increasing environmental awareness, effective use of natural energy has been actively promoted aiming at a low-carbon society. Looking at buildings, heat inflow occurs in summer and heat outflow in winter through openings such as window glass, which contributes to an increase in energy used for air conditioning. As one of the methods for solving such problems, the window glass is coated with a vanadium dioxide-based material adjusted so that a thermochromic phenomenon occurs near room temperature, thereby preventing wasteful heat inflow and cooling. Realization of energy saving is under consideration.

  By the way, it is generally regarded as a difficult technique to form a high-quality vanadium dioxide thin film having a monoclinic crystal structure. For example, as described in Patent Document 1 and Patent Document 2, in order to form a thin film by reactive sputtering using a vanadium metal or vanadium alloy target, oxygen in a very limited range is used. It is necessary to control the ratio.

  As a solution to such a problem, Patent Document 3 proposes a thermochromic body having a transition metal underlayer and a method for manufacturing the same in order to form a vanadium dioxide film in a wide range of oxygen gas flow ratios. Has been. However, in the technique described in Patent Document 3, although the effect of widening the oxygen gas flow rate ratio in the sputtering atmosphere can be obtained by the transition metal underlayer, the coloring due to the transition metal underlayer is large, so that the visible light transmittance is high. This will cause a problem of lowering.

Since the vanadium dioxide-based thin film exhibits light absorption in the visible range, it is required to have excellent crystallinity so that thermochromic characteristics can be exhibited with a thin film thickness. However, when a thin film is directly formed on a glass substrate, a film whose main component is a vanadium dioxide (VO ₂ ) phase cannot be obtained unless the film thickness is more than a certain value, that is, more than necessary. This is an issue.

For example, Non-Patent Document 1 discloses that when a film is formed by reactive RF magnetron sputtering using a V ₂ O ₃ oxide target at a substrate temperature of 400 ° C., the V ₄ O ₉ phase has a thickness of about 200 nm. It is described that a VO ₂ phase becomes a main component when the film becomes a main component film and the film thickness exceeds 500 nm. Similarly, when film formation by reactive RF magnetron sputtering in an Ar-5% H ₂ atmosphere using a V ₂ O ₅ oxide target is performed, an amorphous film is formed at a film thickness of 100 nm or less. It is described that when the film thickness exceeds 400 nm, a VO ₂ phase film can be obtained. Actually, since it is necessary to reduce the film thickness to at least 100 nm in order to reduce light absorption in the visible range, practical application is currently difficult in direct film formation on a glass substrate.

As a method for solving this problem, Non-Patent Document 2 discloses that VO ₂ is formed by forming ZnO having a thickness of 30 nm or less on a glass substrate as a base film in the same process as Non-Patent Document 1, even with a film thickness of 100 nm or less. It is described that phase film formation is possible. The ZnO underlayer used in Non-Patent Document 2 is also superior in that it absorbs less visible light than the transition metal underlayer used in Patent Document 3.

As described above, by using ZnO as a base film, a thin VO ₂ phase film having a film thickness of 100 nm or less can be formed. That is, whether or not the substrate temperature is lowered is unknown. When considering industrial use, there is a concern that the substrate temperature of Non-Patent Document 2 (temperature exceeding 300 ° C.) is too high. Glass is vulnerable to thermal distortion. Therefore, in large glass, it is necessary to make the heating / cooling speed very slow. When the substrate temperature increases, it takes time to raise and lower the temperature, and thus the productivity is lowered.

  In an application where a vanadium dioxide-based thin film is coated on a window glass as a heat ray shielding film, for example, when a sputtering film is formed on a large glass substrate, a uniform temperature distribution with little unevenness is required. When the temperature distribution occurs, there is an increased risk of stress being generated and breaking the glass substrate. In order to avoid this danger, a gradual temperature increase / decrease is required, but since the time required for the process becomes longer, the productivity becomes worse.

  As described above, when the substrate temperature is increased, a manufacturing problem occurs. On the other hand, there is a problem that the heat resistance of the film is not sufficient in the application to coat the film. In particular, when using a highly versatile PET (Polyethylene Terephthalate) film, heat resistance at 100 ° C. or lower is required.

JP-A-7-331430 JP-A-8-3546 JP 2000-137251 A JP 2007-22837 A

Jpn. J. et al. Appl. Phys. Vol. 39 (2000) pp. 6016-6024 Jpn. J. et al. Appl. Phys. Vol. 42 (2003) p. 6523-6651 Jpn. J. et al. Appl. Phys. Vol. 43 (2004) p. 186-187

An object of the present invention is to provide a thermochromic body and a method for producing a thermochromic body capable of forming a vanadium dioxide-based thin film composed of a VO ₂ phase having better crystallinity at a lower temperature than in the past. And

As a result of intensive studies to solve the above-mentioned problems, the present inventors have formed VO ₂ having high crystallinity at low temperature by forming a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide as a base film. The inventors have found that a phase film can be formed, and have completed the present invention.

  That is, the thermochromic body according to the present invention includes a base film made of a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide, and a vanadium dioxide-based thin film formed on the base film. .

  The thermochromic body according to the present invention is characterized in that the amount of magnesium added to the base film is 0.01 to 1.0 in terms of the Mg / (Mg + Zn) atomic ratio.

  In the thermochromic body according to the present invention, the base film is made of an oxide thin film in which zinc is added to magnesium oxide, and the amount of magnesium added to the base film is 0.00 in terms of the number of magnesium atoms represented by Mg / (Mg + Zn). It is characterized by being 01-0.18.

  In the thermochromic body according to the present invention, the base film is formed by adding aluminum and / or gallium to an oxide thin film obtained by adding zinc to magnesium oxide, and the amount of magnesium added is represented by Mg / (Mg + Zn + Al + Ga). The magnesium atom number ratio is 0.01 to 0.18, and the aluminum and / or gallium atom number ratio represented by (Al + Ga) / (Mg + Zn + Al + Ga) is 0.05 or less.

  The thermochromic body according to the present invention is characterized by further comprising a silicon oxide thin film on the vanadium dioxide thin film.

Thermochromic body according to the present invention, the wavelength lambda _0, the optical thickness of lambda _0/4 of the base film, the optical film thickness lambda _0/2 of the vanadium dioxide thin film, an optical film thickness of the silicon oxide thin film lambda ₀ / 4.

Thermochromic material according to the present invention is the wavelength lambda ₀ is 200 to 400 nm, if the wavelength lambda ₃ is a range of not less than 700nm exceeds the lambda _0, the optical thickness of the underlying film lambda _0/4, dioxide the optical thickness of the vanadium-based thin film λ _0/2, characterized by the optical thickness of the silicon oxide thin film and λ _3/4.

Thermochromic material according to the present invention is the wavelength lambda ₀ is 200 to 400 nm, when the wavelength lambda ₁ is in the range below 700nm beyond lambda _0, the optical thickness of the base film lambda _1/4, dioxide the optical thickness of the vanadium-based thin film λ _0/2, characterized by the optical thickness of the silicon oxide thin film and λ _0/4.

In the thermochromic body according to the present invention, when the wavelength λ ₀ is 200 to 400 nm and the wavelengths λ ₁ and λ ₃ are in the range of more than λ ₀ and 700 nm or less, the optical film thickness of the base film is λ ₁ / 4, λ _0/2 optical thickness of vanadium dioxide thin film, characterized in that the optical thickness of the silicon oxide thin film and λ _3/4.

  In the method for producing a thermochromic body according to the present invention, a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide is formed as a base film on a substrate, and a vanadium dioxide thin film is formed on the base film. It is characterized by.

According to the present invention, by using an underlayer containing magnesium oxide, a vanadium dioxide thin film composed of a VO ₂ phase having good crystallinity at a lower temperature, for example, near room temperature can be formed.

It is sectional drawing which shows the structural example of the thermochromic body of the 2 layer laminated film structure which concerns on this Embodiment. It is sectional drawing which shows the structural example of the thermochromic body of the 3 layer laminated film structure which concerns on this Embodiment. It is a graph which shows the X-ray-diffraction result of the thermochromic body of the 2 layer laminated film structure which used the oxide thin film containing magnesium, zinc, and gallium for a base film. It is a graph which shows the measurement result of the transmittance | permeability and reflectance of a thermochromic body. It is a graph which shows the measurement result of the transmittance | permeability of the thermochromic body measured at room temperature and 80 degreeC. It is a graph which shows the X-ray-diffraction result of the thermochromic body of the 2 layer laminated film structure which used the zinc oxide thin film for the base film.

Hereinafter, an example of a specific embodiment to which the present invention is applied (hereinafter referred to as “the present embodiment”) will be described in detail in the following order.
1. Thermochromic body2. 2. Production method of thermochromic body 3. Application example of thermochromic body Example

<1. Thermochromic body>
<1-1.2 layered film structure>
FIG. 1 is a cross-sectional view showing a configuration example of a thermochromic body 1 having a two-layer laminated film structure. As shown in FIG. 1, the thermochromic body 1 according to the present invention is formed on a base 10 and a base film 11 made of a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide, and the base film 11. And a vanadium dioxide-based thin film 12.

  Although it does not specifically limit as the base | substrate 10, For example, a glass substrate can be used. Moreover, as the base | substrate 10, a various resin substrate may be used and a highly transparent thing is preferable. When the film is formed in the range of room temperature to 100 ° C., a highly versatile polyethylene terephthalate (PET) substrate can be used as the substrate 10. When the film is formed at a substrate temperature exceeding 100 ° C., a high heat resistant resin substrate having high heat resistance can be used as the substrate 10. High heat-resistant resin substrates include polycarbonate (PC), polyethylene naphthalate (PEN), polyarylate (PAR), polyethersulfone (PES), transparent polyimide (PI), Arton, Silplus, and transparent polyamideimide (PAI). ) And the like. In addition, room temperature which shows the temperature at the time of film-forming means the range of about 15-30 degreeC.

  As the base film 11, a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide is used. As a result, the vanadium dioxide thin film 12 can be formed with good crystallinity at a low substrate temperature.

  For example, the vanadium dioxide thin film 12 can be formed at a lower substrate temperature than when the ZnO thin film described in Non-Patent Document 2 described above is used as the base film 11. Magnesium has a higher oxygen affinity than zinc. Therefore, by using the magnesium oxide thin film or the oxide thin film obtained by adding zinc to magnesium oxide as the base film 11, the excess oxygen of the vanadium dioxide thin film 12 is reduced as compared with the case where the ZnO thin film is used as the base film 11. It can be absorbed more effectively. Thereby, the amount of oxygen in the vanadium dioxide thin film 12 can be automatically and precisely optimized, and a film with good crystallinity can be formed.

  Here, the magnesium content of the base film 11 is preferably 0.01 to 1.0 in terms of the number of magnesium atoms represented by Mg / (Zn + Mg). When the magnesium atom number ratio is less than 0.01, the vanadium dioxide thin film 12 cannot be formed with good crystallinity at a low substrate temperature. When the magnesium atom number ratio exceeds 1.0, the vanadium dioxide thin film 12 cannot be formed with good crystallinity at a low substrate temperature.

  In addition, when an oxide target is used as a starting material and the base film 11 is formed by a direct current sputtering method, the magnesium atom number ratio is more preferably 0.01 to 0.18.

  Further, for the purpose of increasing the conductivity of the oxide target and facilitating direct current sputtering, aluminum and / or gallium may be further added to the oxide thin film in which zinc is added to magnesium oxide of the base film 11. In that case, the magnesium content is 0.01 to 0.18 in terms of the number of magnesium atoms expressed by Mg / (Zn + Mg + Al + Ga), and / or aluminum expressed by (Al + Ga) / (Zn + Mg + Al + Ga) and / or The gallium atom number ratio is preferably 0.05 or less. If the magnesium atom number ratio exceeds 0.18, arcing is likely to occur, making DC sputtering difficult. Also, when the aluminum and / or gallium atomic ratio exceeds 0.05, arcing is likely to occur in DC sputtering.

  The underlying film 11 has high transparency and small absorption of visible light, and thus the film thickness is not particularly limited, but the film thickness is preferably 100 nm or less.

The vanadium dioxide thin film 12 is formed on a base film 11 made of a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide. The crystal phase of the vanadium dioxide thin film 12 needs to be a monoclinic VO ₂ phase. When the VO ₂ phase exceeds the transition point, it transforms into a tetragonal VO ₂ phase represented by the space group P4 ₂ / mnm, thereby exhibiting thermochromic characteristics.

  The vanadium dioxide thin film 12 is not only composed of vanadium and oxygen, but may also contain one or more metal elements selected from the metal element group consisting of tungsten, molybdenum, tantalum and niobium. In particular, in order to control the transition point, it is preferable that the vanadium dioxide thin film 12 contains tungsten or molybdenum. Specifically, the tungsten content is preferably 0.1 or less, more preferably 0.01 to 0.02, in terms of the atomic ratio represented by W / (V + W). Moreover, as content of molybdenum, 0.1 or less is preferable at the atomic ratio represented by Mo / (V + Mo), and 0.02-0.045 is more preferable. However, the inevitable impurities are not limited thereto.

This vanadium dioxide-based thin film 12 is a monoclinic crystal represented by the space group P2 ₁ / c described in JCPDS card 44-0252 in a temperature range below the transition point from the viewpoint that excellent thermochromic properties can be obtained. It is necessary to take the crystal structure of the system. By adopting this monoclinic crystal structure, when the above metal element group is not added, the semiconductor-metal phase transition occurs at a transition temperature of 68 ° C., and the space group P4 ₂ described in 44-0253 of the same card is used. Transition to a tetragonal rutile crystal structure represented by / mnm. On the other hand, when an appropriate amount of the metal element group described above is included, the transition temperature at 68 ° C. can be controlled to be near room temperature.

As described above, by using the base film 11 containing magnesium oxide, it is possible to form the vanadium dioxide thin film 12 composed of the VO ₂ phase having good crystallinity at a lower temperature, that is, near room temperature, and a favorable thermostat. The chromic body 1 can be formed.

<1-2.3 layer laminated film structure>
FIG. 2 is a cross-sectional view showing a configuration example of a thermochromic body 2 having a three-layer laminated film structure. In the following description of the thermochromic body 2, the same components as those of the thermochromic body 1 shown in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The thermochromic body 2 shown in FIG. 2 includes a base film 11 formed on a substrate 10, a vanadium dioxide thin film 12 formed on the base film 11, and a silicon oxide formed on the vanadium dioxide thin film 12 ( Silicon oxide) thin film 13. The thermochromic body 2 is different from the thermochromic body 1 described above in that it includes a silicon oxide thin film 13.

  As described in Non-Patent Document 3 described above, the vanadium dioxide thin film 12 has a high refractive index. Therefore, by forming the silicon oxide thin film 13 having a low refractive index on the vanadium dioxide-based thin film 12, the light reflectance at the outermost surface of the thermochromic body 2 can be effectively reduced.

Thermochromic body 2 comprises a silicon oxide film 13, an optical film thickness lambda _0/4 of the base film 11, an optical film thickness lambda _0/2 of the vanadium dioxide-based thin film 12, and the optical thickness of the silicon oxide film 13 it is preferable that the λ _0/4. Here, the wavelength λ ₀ is preferably 400 nm or less, and more preferably 200 to 400 nm.

The optical thickness of the silicon oxide film 13 may be thicker than lambda _0/4 in which the optical thickness described above of the optical thickness or the base film 11 and silicon oxide film 13, base film 11. Thereby, the transmittance | permeability of the visible light in the thermochromic body 2 can be made higher.

  In general, in the antireflection structure, the wavelength at which the antireflection effect is obtained in the visible light region and the wavelength exhibiting the maximum transmittance substantially coincide with each other by being constituted by a highly transparent film. Therefore, in order to improve the transmittance in the visible light region, the wavelength 550 nm with high visibility may be set as the center wavelength λ. In this case, the optical film thickness of the low refractive index layer that is the first layer is λ / 4, the optical film thickness of the high refractive index layer that is the second layer is λ / 2, The optical film thickness of the low refractive index layer or the intermediate refractive index layer to be a layer is designed to be λ / 4.

The thermochromic body 2 has a film structure similar to such a normal antireflection structure. However, since the thermochromic body 2 includes the vanadium dioxide-based thin film 12 that absorbs a relatively large amount of visible light as the second layer, the central wavelength of the antireflection effect does not match the wavelength indicating the maximum transmittance in the visible light region. . Therefore, by examining the change in transmittance of the thermochromic body 2 in the visible light region while changing the wavelength λ, the wavelength λ ₀ that provides good transmittance is determined. Specifically, when the wavelength λ ₀ exceeds 400 nm, the absorption of light on the short wavelength side of the visible light region with a wavelength of 400 to 500 nm increases, and the transmittance at a wavelength of 500 nm falls below 40%.

Thermochromic body 2, the wavelength lambda ₀ in determining the optical film thickness is 400nm or less, more preferably from 200 to 400 nm, the optical thickness of the underlying film 11 λ _0/4, the vanadium dioxide-based thin film 12 the optical film thickness and λ _0/2, it is preferable that the optical film thickness lambda _3/4 of the silicon oxide film 13 thicker than λ _0/4. In determining the optical film thickness lambda _3/4 of the silicon oxide film 13, it lambda ₃ is in a range below 700nm beyond lambda _0, i.e., it is more preferable to satisfy the λ ₀ <λ ₃ ≦ 700nm , 500 nm or less in the range beyond the lambda _0, i.e., it is more preferable to satisfy the λ ₀ <λ ₃ ≦ 500nm.

Also, thermochromic body 2, the wavelength lambda ₀ in determining the optical film thickness is 400nm or less, more preferably from 200 to 400 nm, the optical thickness of the vanadium dioxide-based thin film 12 lambda _0/2, silicon oxide the optical thickness of the thin film 13 and λ _0/4, it is preferable that the optical film thickness lambda _1/4 of the base film 11 thicker than λ _0/4. When determining the optical film thickness lambda _1/4 of the base film 11, it lambda ₁ is in the range below 700nm beyond lambda _0, i.e., it is more preferable to satisfy the _{λ 0 <λ 1 ≦ 700nm,} λ 0 More preferably, it is in the range of less than or equal to 500 nm, that is, satisfying λ ₀ <λ ₁ ≦ 500 nm.

Further, thermochromic body 2 is less than the wavelength lambda ₀ is 400nm in determining the optical film thickness, more preferably from 200 to 400 nm, the optical thickness of the vanadium dioxide-based thin film 12 and the lambda _0/2, under it is more preferable that the optical film thickness lambda _3/4 optical film thickness lambda _1/4 and the silicon oxide film 13 of Chimaku 11 thicker than λ _0/4. In determining the optical film thickness lambda _3/4 optical film thickness lambda _1/4 and the silicon oxide film 13 of the base film 11, it lambda ₁ and lambda ₃ is in a range below 700nm beyond lambda _0, That is, it is more preferable to satisfy λ ₀ <λ ₁ , λ ₃ ≦ 700 nm, and it is more preferable that λ ₀ is in the range of 500 nm or less and λ ₀ <λ ₁ , λ ₃ ≦ 500 nm.

  As described above, the thermochromic body 2 having a high visible light transmittance can be formed by further forming the silicon oxide thin film 13 on the outermost surface of the thermochromic body 1 described above.

Further, the thermochromic body 2 to the base film 11, and / or thicker than lambda _0/4 as described above the optical film thickness of the silicon oxide film 13 lambda ₁ and / or lambda ₃ contains magnesium oxide Thus, the visible light transmittance can be improved.

  The film structure of the thermochromic body according to the present embodiment may be further multi-layered, but the cost increases as the number of layers increases.

<2. Method for producing thermochromic body>
In the thermochromic body 1 according to the present embodiment, a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide is formed as a base film 11 on a base 10, and a vanadium dioxide thin film 12 is formed on the base film 11. It is obtained by forming.

  For example, a well-known film forming method on the substrate 10, for example, a sputtering method described in Patent Document 1 described above, a physical film forming method such as an ion plating method, a PLD method, or the like described in Patent Document 4 described above. The thermochromic body 1 can be formed by applying chemical film-forming methods such as CVD (Chemical Vapor Deposition), spraying, and MOD (Metal Organic Decompositon).

  In the method of forming the thermochromic body 1, it is particularly preferable to use a sputtering method. Specifically, a direct current sputtering method, a direct current pulse sputtering method, or a high frequency sputtering method may be used. Among these sputtering methods, it is preferable to use high-frequency sputtering to form the vanadium dioxide thin film 12, and it is particularly preferable to use a vanadium oxide sintered body target.

  Moreover, when using a vanadium-type metal target, the direct current | flow pulse sputtering method can also be used suitably. The DC pulse sputtering method employs a frequency of several hundred kHz lower than the general frequency of 13.56 MHz in the high frequency sputtering method, or changes the waveform of the applied current and applied voltage (for example, changes to a rectangular shape). And included in the DC sputtering method. It is possible to form a film while suppressing arcing by periodically stopping the negative voltage applied to the target and applying a low positive voltage therebetween to neutralize positive charging with electrons. Thereby, there is no need to control the impedance matching circuit as in the high frequency sputtering method, and there is an advantage that the film forming speed is faster than the high frequency sputtering method. Further, the vanadium dioxide thin film 12 can be formed by precisely controlling the optimum oxygen amount in combination with a PEM (Plasma Emission Monitor) or the like. In addition, even if it is direct current | flow sputtering method or direct current | flow pulse sputtering method, in order to implement | achieve high-speed film-forming, a conductive target is required for all.

When the thermochromic body 1 is formed by various sputtering methods, it is preferable to use a mixed gas composed of an inert gas and oxygen, particularly argon and oxygen, as the sputtering gas. Further, it is preferable to perform sputtering in a chamber of the sputtering apparatus at a pressure of 0.1 to 5 Pa, particularly 0.2 to 0.8 Pa. For example, after evacuating to 2 × 10 ⁻⁴ Pa or less, a mixed gas composed of argon and oxygen is introduced, the gas pressure is set to 0.2 to 0.5 Pa, and direct current power with respect to the area of the target, that is, direct current power density It is preferable to perform pre-sputtering by generating a plasma by applying electric power so that is in a range of about 1 to 3 W / cm ² . After performing this pre-sputtering for 5 to 30 minutes to stabilize the discharge state, it is preferable to perform sputtering film formation after correcting the position of the substrate 10 as necessary.

  In addition, the thermochromic body 1 can be formed by heating the substrate 10 to a predetermined temperature to form a crystal film in which each layer has a desired structure. The temperature of the substrate 10 is preferably room temperature or higher and 500 ° C. or lower. When the temperature of the substrate 10 is lower than room temperature, it is necessary to provide a cooling treatment for the film forming apparatus, which causes a harmful effect such as an increase in cost. Alternatively, an amorphous film may be formed at a low temperature near room temperature, and then the crystal film may be formed by heat treatment in an appropriate atmosphere such as non-oxidizing property.

As described above, in the method for forming the thermochromic body 1, the base film 11 containing magnesium oxide is formed, and the vanadium dioxide thin film 12 is formed on the base film 11. Therefore, the vanadium dioxide thin film 12 composed of a VO ₂ phase having good properties can be formed. Therefore, a favorable thermochromic body 1 can be formed.

  Moreover, in the formation method of the thermochromic body 1, the thermochromic body 2 with a high visible light transmittance | permeability is formed by further forming the silicon oxide thin film 13 on the outermost surface of the thermochromic body 1, ie, the vanadium dioxide type thin film 12. Can be formed.

<3. Application example of thermochromic body>
The thermochromic body according to the present embodiment described above can be suitably applied to, for example, a heat ray shielding glass or a heat ray shielding film. The heat ray shielding glass or the heat ray shielding film is obtained, for example, by using glass or a film as the base 10, forming the base film 11 on the base 10, and forming the vanadium dioxide thin film 12 on the base film 11. By forming the vanadium dioxide thin film 12 on the base film 11 formed on the glass or film as the base 10, the material of the base 10 is not limited. For example, for a non-heat resistant film or the like. The vanadium dioxide thin film 12 composed of the VO ₂ phase having good crystallinity near room temperature can be formed.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[Evaluation of basic properties of thin film]
The composition of the thin film of each layer obtained in the following Examples and Comparative Examples was examined by ICP emission spectroscopy. The film thickness of each layer was measured with a surface roughness meter (Alpha-Step IQ, manufactured by Tencor). The film formation rate was calculated from the film thickness and the film formation time.

  The formation phase of the film was identified by 2θ / θ measurement using an X-ray diffractometer (Philips X′Pert PRO MPD).

As thermochromic properties, using a spectrophotometer (manufactured by Hitachi High-Technologies U-4100 type), and measuring the transmittance at room temperature and 80 ° C., it was determined transmittance difference of wavelength 1500nm as [Delta] T _1500.

(Examples 1-6)
In Examples 1-6, the thermochromic body of the 2 layer laminated film structure which formed the vanadium dioxide thin film on the magnesium oxide thin film which is a base film was formed.

  Film formation is performed using a magnesium oxide oxide sintered body and a vanadium dioxide oxide sintered body on a cathode for a non-magnetic target of a magnetron sputtering apparatus (SPF-530H manufactured by Anelva) equipped with a direct current power source and a high frequency power source having no arcing suppression function. The two types of sputtering targets were attached.

Further, a Corning 7059 glass substrate having a thickness of 1.1 mm was used as the substrate. The inside of the chamber of the sputtering apparatus is evacuated to a vacuum of 1 × 10 ⁻⁴ Pa or less, and a predetermined substrate temperature, that is, room temperature (Example 1), 100 ° C. (Example 2), 200 ° C. (Example 3), It was confirmed that the temperature reached 300 ° C. (Example 4), 400 ° C. (Example 5), and 500 ° C. (Example 6).

  Specifically, in Examples 1 to 6, a thermochromic body having a two-layer laminated film structure was formed by the following operation.

  First, a magnesium oxide thin film was formed as a base film on a glass substrate. Magnesium oxide thin film introduces a mixed gas of argon and oxygen so that the ratio of oxygen is 0.5%, adjusts the total gas pressure to 0.5 Pa, and generates high frequency plasma by applying high frequency power 200 W. The film was formed by high frequency sputtering. The distance between the target and the substrate was 60 mm.

  This magnesium oxide thin film is formed by pre-sputtering for 10 minutes, placing a substrate immediately above the sputtering target, that is, at a stationary facing position, and performing sputtering at a predetermined substrate temperature to form a magnesium oxide thin film having a thickness of 30 nm. Formed.

  Next, a vanadium dioxide thin film was formed on the magnesium oxide thin film. The vanadium dioxide thin film is a mixed gas of argon and oxygen introduced so that the ratio of oxygen is 0.3%, the gas pressure is adjusted to 0.5 Pa, high frequency power 200 W is applied to generate high frequency plasma, The film was formed by high frequency sputtering. The target-substrate distance was 60 mm.

  This vanadium dioxide thin film is formed by pre-sputtering for 10 minutes, placing a substrate immediately above the sputtering target, that is, at a stationary facing position, and performing sputtering at the same substrate temperature as the magnesium oxide thin film. A 160 nm vanadium dioxide thin film was formed.

As a result of examining the thermochromic body having a two-layer laminated film structure formed through the above process by X-ray diffraction measurement, VO ₂ composed of a monoclinic crystal structure of the space group P2 ₁ / c at all substrate temperatures. Phase formation was confirmed.

The vanadium dioxide thin film of the second layer is a thin film in which 0.015 is added to vanadium dioxide at an atomic ratio expressed by W / (V + W), or molybdenum is added to vanadium dioxide by Mo / (V + Mo). Similarly, even in a thin film added with 0.032 in the atomic ratio, formation of a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c was confirmed at all substrate temperatures. All of these thin films had a transition temperature of 32 ° C.

(Examples 7 to 12)
In Examples 7 to 12, instead of magnesium oxide, magnesium oxide having a magnesium content of 0.30 in terms of the atomic ratio represented by Mg / (Mg + Zn) and zinc content of Zn was used as the base film. / A sputtering apparatus and a substrate similar to those in Examples 1 to 6 except that a sputtering target made of an oxide sintered body containing zinc which is 0.70 in terms of the atomic ratio represented by (Mg + Zn) is used. The thermochromic body was produced using. The substrate temperatures were room temperature (Example 7), 100 ° C. (Example 8), 200 ° C. (Example 9), 300 ° C. (Example 10), 400 ° C. (Example 11), 500 ° C. (Example 12). It was.

  Specifically, an oxide thin film containing magnesium and zinc serving as a base film on a glass substrate is formed by introducing only argon gas using the above-described sputtering target, a gas pressure of 0.3 Pa, and a target-substrate distance. Was adjusted to 60 mm, and a high frequency power of 200 W was applied to form a film by high frequency sputtering. In the film forming process, after pre-sputtering for 10 minutes, a substrate was placed immediately above the sputtering target, that is, at a stationary facing position, and sputtering was performed at a predetermined substrate temperature to form the same thin film having a thickness of 30 nm.

  Next, a vanadium dioxide thin film was formed on the base film by the same process as in Examples 1-6.

As a result of examining the thermochromic body having a two-layer laminated film structure formed through the above process by X-ray diffraction measurement, VO ₂ composed of a monoclinic crystal structure of the space group P2 ₁ / c at all substrate temperatures. Phase formation was confirmed.

The vanadium dioxide thin film of the second layer is a thin film in which 0.015 is added to vanadium dioxide at an atomic ratio expressed by W / (V + W), or molybdenum is added to vanadium dioxide by Mo / (V + Mo). Similarly, even in a thin film added with 0.032 in the atomic ratio, formation of a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c was confirmed at all substrate temperatures. All of these thin films had a transition temperature of 32 ° C.

(Examples 13 to 18)
In Examples 13 to 18, instead of magnesium oxide, the underlying film is magnesium content of 0.18 in terms of the number of atoms expressed by Mg / (Mg + Zn + Al), and the zinc content is Zn / (Mg + Zn + Al). Sputtering made of an oxide sintered body containing magnesium, zinc and aluminum having an atomic ratio of 0.77 and an aluminum content of 0.05 by atomic ratio represented by Al / (Mg + Zn + Al) Except for using the target, the substrate temperature was room temperature (Example 13), 100 ° C. (Example 14), 200 ° C. (Example 15), 300 ° C. (Example 16), 400 ° C. (Example 17). ), At 500 ° C. (Example 18), a thermochromic body was prepared using the same sputtering apparatus and substrate as in Examples 1-6.

  Specifically, an oxide thin film containing magnesium, zinc, and aluminum serving as a base film on a glass substrate is formed by introducing only argon gas using the above-described sputtering target, the gas pressure is 0.5 Pa, and the target-substrate. The distance was adjusted to 49 mm, a DC power of 200 W was applied, and a film was formed by DC sputtering. In the film forming process, after pre-sputtering for 10 minutes, a substrate was placed immediately above the sputtering target, that is, at a stationary facing position, and sputtering was performed at a predetermined substrate temperature to form the same thin film having a thickness of 30 nm.

  Next, a vanadium dioxide thin film was formed on the base film by the same process as in Examples 1-6.

As a result of examining the thermochromic body having a two-layer laminated film structure formed through the above process by X-ray diffraction measurement, VO ₂ composed of a monoclinic crystal structure of the space group P2 ₁ / c at all substrate temperatures. Phase formation was confirmed.

(Examples 19 to 24)
In Examples 19 to 24, as the base film, instead of magnesium oxide, the magnesium content was 0.105 in terms of the atomic ratio represented by Mg / (Mg + Zn + Ga), and the zinc content was Zn / (Mg + Zn + Ga). Sputtering made of an oxide sintered body containing magnesium, zinc and gallium having an atomic ratio represented by 0.845 and a gallium content of 0.05 by atomic ratio represented by Ga / (Mg + Zn + Ga) A thermochromic body was produced using the same sputtering apparatus and substrate as in Examples 1 to 6 except that the target was used. The substrate temperatures were room temperature (Example 19), 100 ° C. (Example 20), 200 ° C. (Example 21), 300 ° C. (Example 22), 400 ° C. (Example 23), 500 ° C. (Example 24). It was.

  Specifically, an oxide thin film containing magnesium, zinc, and gallium serving as a base film on a glass substrate uses the above-described sputtering target, introduces only argon gas, and sets the gas pressure to 0.5 Pa. The distance was adjusted to 49 mm, a DC power of 200 W was applied, and a film was formed by DC sputtering. In the film forming process, after pre-sputtering for 10 minutes, a substrate was placed immediately above the sputtering target, that is, at a stationary facing position, and sputtering was performed at a predetermined substrate temperature to form the same thin film having a thickness of 30 nm.

  Next, a vanadium dioxide thin film was formed on the base film by the same process as in Examples 1-6.

As a result of examining the thermochromic body having a two-layer laminated film structure formed through the above process by X-ray diffraction measurement, VO ₂ composed of a monoclinic crystal structure of the space group P2 ₁ / c at all substrate temperatures. Phase formation was confirmed.

FIG. 3 is a graph showing an X-ray diffraction result of a thermochromic body having a two-layer laminated film structure in which an oxide thin film containing magnesium, zinc and gallium is used as a base film. In FIG. 3, a black circle symbol (●) indicates a peak corresponding to a VO ₂ phase having a monoclinic crystal structure of the space group P2 ₁ / c. In FIG. 3, a black triangle symbol (▲) indicates a peak corresponding to the ZnO phase.

The vanadium dioxide thin film of the second layer is a thin film in which 0.015 is added to vanadium dioxide at an atomic ratio expressed by W / (V + W), or molybdenum is added to vanadium dioxide by Mo / (V + Mo). Similarly, even in a thin film added with 0.032 in the atomic ratio, formation of a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c was confirmed at all substrate temperatures. All of these thin films had a transition temperature of 32 ° C.

(Examples 25-30)
In Examples 25 to 30, instead of magnesium oxide, the underlying film is 0.01 in terms of the atomic ratio represented by Mg / (Mg + Zn + Ga + Al), and the zinc content is Zn / (Mg + Zn + Ga) instead of magnesium oxide. The atomic ratio represented by + Al) is 0.94, the aluminum content is 0.025 by the atomic ratio represented by Al / (Mg + Zn + Ga + Al), and the gallium content is represented by Ga / (Mg + Zn + Ga + Al). A sputtering apparatus and a substrate similar to those of Examples 1 to 6 except that a sputtering target made of an oxide sintered body containing magnesium, zinc, aluminum, and gallium having an atomic ratio of 0.025 is used. The thermochromic body was produced using. The substrate temperatures were room temperature (Example 25), 100 ° C. (Example 26), 200 ° C. (Example 27), 300 ° C. (Example 28), 400 ° C. (Example 29), 500 ° C. (Example 30). It was.

  Specifically, an oxide thin film containing magnesium, zinc, aluminum, and gallium, which serves as a base film on a glass substrate, uses the above-described sputtering target, introduces only argon gas, and sets the gas pressure to 0.5 Pa. -The distance between the substrates was adjusted to 49 mm, and a DC power of 200 W was applied to form a film by DC sputtering. In the film forming process, after pre-sputtering for 10 minutes, a substrate was placed immediately above the sputtering target, that is, at a stationary facing position, and sputtering was performed at a predetermined substrate temperature to form the same thin film having a thickness of 30 nm.

  Next, a vanadium dioxide thin film was formed on the base film by the same process as in Examples 1-6.

As a result of examining the thermochromic body having a two-layer laminated film structure formed through the above process by X-ray diffraction measurement, VO ₂ composed of a monoclinic crystal structure of the space group P2 ₁ / c at all substrate temperatures. Phase formation was confirmed.

(Example 31)
In Example 31, a thermochromic body was produced using the same sputtering apparatus as in Example 7 having a substrate temperature of room temperature, except that a PET film having a thickness of 100 μm was used as the substrate instead of the glass substrate.

As a result of examining the crystallinity of the formed thermochromic body by X-ray diffraction measurement, it was confirmed that a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c was formed.

Table 1 collectively shows the substrate temperature, the type of the underlayer, and the possibility of VO ₂ phase generation when a vanadium dioxide thin film is formed in each example.

(Example 32)
In Example 32, a base film (first layer) made of an oxide thin film obtained by adding zinc and gallium to magnesium oxide, a vanadium dioxide thin film (second layer) formed on the base film, and a vanadium dioxide thin film The thermochromic body provided with the silicon oxide thin film (third layer) formed on was formed. The thermochromic material is a wavelength lambda _{0 =} 300 nm, the optical thickness of the base film and the silicon oxide thin film is lambda _0/4, such that the optical thickness of the vanadium dioxide thin film is lambda _0/2, physical The film thickness was adjusted.

  Film formation is represented by the Mg content of Mg / (Mg + Zn + Ga) on the nonmagnetic target cathode of a magnetron sputtering apparatus (SPF-530H manufactured by Anelva) equipped with a DC power source and a high frequency power source without arcing suppression function. The atomic ratio is 0.105, the zinc content is 0.845 by the atomic ratio represented by Zn / (Mg + Zn + Ga), and the gallium content is 0.8 by the atomic ratio represented by Ga / (Mg + Zn + Ga). It was carried out by attaching three types of sputtering targets of 05, oxide sintered body containing magnesium, zinc and gallium, vanadium dioxide oxide sintered body and silicon.

As the substrate, a Corning 7059 glass substrate having a thickness of 1.1 mm was used. It was confirmed that the inside of the chamber of the sputtering apparatus was evacuated to a vacuum of 1 × 10 ⁻⁴ Pa or less and reached a substrate temperature of 400 ° C.

  Specifically, in Example 32, a thermochromic body having a three-phase structure was formed by the following operation.

First, an oxide thin film obtained by adding zinc and gallium magnesium oxide as a base film on a glass substrate by the same process as in Example 23, the optical thickness _{λ 0/4 (λ 0 =} 300nm) at a film thickness of corresponding Formed.

Next, a vanadium dioxide thin film was formed on the base film with an optical film thickness λ ₀ by the same process as in Examples 1 to 5 except that the oxygen flow rate ratio was 0.7% with the substrate temperature maintained at 400 ° C. / 2 equivalent film thickness.

  Furthermore, while maintaining the substrate temperature at 400 ° C., a silicon oxide thin film was formed using silicon as a target. The silicon oxide thin film introduces a mixed gas of argon and oxygen so that the oxygen ratio becomes 2%, adjusts the gas pressure to 0.5 Pa, applies high frequency power 200 W to generate high frequency plasma, and generates high frequency sputtering. Was deposited. The target-substrate distance was 60 mm.

Film formation process of the silicon oxide film, after the pre-sputtering for 10 minutes, immediately above the sputtering target, i.e. the substrate is placed in a stationary position facing was formed of the same thin film thickness of the optical film thickness lambda _0/4 corresponds .

  When the physical film thickness of each layer of the thermochromic body having a three-layer laminated film structure formed through the above process was measured, the first layer was 40 nm, the second layer was 45 nm, and the third layer was 51 nm.

Further, as a result of examining the crystallinity of the thermochromic body by X-ray diffraction measurement, the second layer vanadium dioxide thin film has a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c. It was confirmed that it was generated.

  FIG. 4 is a graph showing measurement results of transmittance and reflectance of the thermochromic body. Moreover, FIG. 5 is a graph which shows the measurement result of the transmittance | permeability of the thermochromic body measured at room temperature and 80 degreeC.

As can be seen from the results shown in FIG. 4 and FIG. 5, the visible light maximum transmittance of the thermochromic body formed in Example 32 is 49.6%, and the transmittance difference at a wavelength of 1500 nm, which is an index of thermochromic characteristics, is ΔT ₁₅₀₀ = 24.9%.

(Example 33)
In Example 33, except that when the optical film thickness of the silicon oxide film (third layer) was lambda _3/4, the wavelength lambda ₃ thickly lambda ₃ = 500 nm considerably from lambda ₃ = 300 nm, Example A thermochromic body was formed as in 32. The physical thickness of the third layer was 85 nm, which was confirmed to be different from Example 32.

As shown in FIG. 4, the visible light maximum transmittance of the thermochromic body formed in Example 33 was 58.3%, and the transmittance difference at a wavelength of 1500 nm was ΔT ₁₅₀₀ = 24.1%.

(Example 34)
In Example 34, when the optical thickness of the base film of an oxide thin film obtained by adding zinc and gallium magnesium oxide (first layer) and lambda _1/4, a wavelength lambda ₁ from lambda _{1 =} 300 nm lambda ₁ = A thermochromic body was formed in the same manner as in Example 32 except that the thickness was equivalent to 500 nm. The physical thickness of the first layer was 65 nm, which was confirmed to be different from Example 32.

As shown in FIG. 4, the visible light maximum transmittance of the thermochromic body formed in Example 34 was 55.0%, and the transmittance difference at a wavelength of 1500 nm was ΔT ₁₅₀₀ = 24.3%.

(Example 35)
In Example 35, the base film (a first layer) made of oxide thin film obtained by adding zinc and gallium magnesium oxide, and the optical thickness of the silicon oxide film (third layer) lambda _1/4 and lambda _3/4 In this case, a thermochromic body was formed in the same manner as in Example 32 except that the wavelength λ ₁ was increased to λ ₁ = 500 nm and the wavelength λ ₃ was increased to be equivalent to λ ₃ = 500 nm. The physical film thicknesses of the first layer and the third layer were 65 nm and 85 nm, respectively, and it was confirmed that they were different from Example 32.

As shown in FIGS. 4 and 5, the visible light maximum transmittance of the thermochromic body formed in Example 35 was 63.1%, and the transmittance difference at a wavelength of 1500 nm was ΔT ₁₅₀₀ = 23.1%. .

(Comparative Examples 1-6)
In Comparative Examples 1 to 6, two layers using the same sputtering apparatus and substrate as in Examples 1 to 6 except that a sputtering target made of a zinc oxide sintered body was used instead of magnesium oxide as the base film. A thermochromic body having a laminated film structure was produced. The substrate temperatures were room temperature (Comparative Example 1), 100 ° C. (Comparative Example 2), 200 ° C. (Comparative Example 3), 300 ° C. (Comparative Example 4), 400 ° C. (Comparative Example 5), 500 ° C. (Comparative Example 6). It was.

  First, the zinc oxide thin film that is the base film on the glass substrate is prepared by using the above-mentioned sputtering target, introducing only argon gas, adjusting the gas pressure to 0.5 Pa, and adjusting the target-substrate distance to 49 mm. A film was formed by DC sputtering with 200 W applied. In the film forming process, after pre-sputtering for 10 minutes, a substrate was placed immediately above the sputtering target, that is, at a stationary facing position, and sputtering was performed at a predetermined substrate temperature to form the same thin film having a thickness of 30 nm.

  Next, a vanadium dioxide thin film was formed on the base film by the same process as in Examples 1-6.

As a result of examining the thermochromic body of the two-layer laminated film structure formed through the above process by X-ray diffraction measurement, it has a monoclinic crystal structure of the space group P2 ₁ / c at a substrate temperature of 200 to 400 ° C. Although a VO ₂ phase was generated, it was confirmed that the substrate temperature was not generated at room temperature and 100 ° C.

FIG. 6 is a graph showing an X-ray diffraction result of a two-layer thermochromic body using a zinc oxide thin film as a base film. In FIG. 6, a black circle symbol (●) indicates a peak corresponding to a VO ₂ phase having a monoclinic crystal structure of the space group P2 ₁ / c. A black triangle symbol (▲) indicates a peak corresponding to the ZnO phase.

(Comparative Example 7)
In Comparative Example 7, only a vanadium dioxide thin film was formed on a substrate of Corning 7059. Specifically, by a similar process except that the oxygen flow rate ratio of 0.7% in the Examples 1-6, the same thickness as in Example 32, i.e. optical thickness _{λ 0/4 (λ 0 =} 300nm) A vanadium dioxide thin film was formed at a substrate temperature of 400 ° C. so as to have a considerable film thickness. However, since the obtained thin film was amorphous with no VO ₂ phase formed, the same thin film was formed with an oxygen flow rate ratio of 0.5%.

As a result of examining the crystallinity of the formed thin film by X-ray diffraction measurement, it was confirmed that a VO ₂ phase composed of a monoclinic crystal structure of the space group P2 ₁ / c was formed.

As shown in FIGS. 4 and 5, the visible light maximum transmittance of the thermochromic body formed in Comparative Example 7 was 43.4%, and the transmittance difference at a wavelength of 1500 nm was ΔT ₁₅₀₀ = 23.1%. .

Tables 1 and 2 below summarize the results of Examples 1 to 33 and Comparative Examples 1 to 7. In Table 2, λ ₀ = 300 nm, λ ₁ = 500 nm, and λ ₃ = 500 nm.

(Evaluation of VO _two- phase generation)
As is clear from the results shown in Table 1 and FIG. 3, when a magnesium oxide thin film is used as the base film (Examples 1 to 6), an oxide thin film containing magnesium and zinc is used as the base film ( In Examples 7 to 12), when an oxide thin film containing magnesium and zinc and gallium and / or aluminum was used as the base film (Examples 13 to 30), the substrate temperature of room temperature to 500 ° C. , It was found that a VO ₂ phase having a monoclinic crystal structure of the space group P2 ₁ / c can be generated.

On the other hand, in the base film ZnO thin films of Comparative Examples 1 to 5, as shown in FIG. 6, a VO ₂ phase is generated at a substrate temperature of 200 to 500 ° C., but at a substrate temperature of room temperature to 100 ° C., VO _2. It was found that no phase could be generated.

From the above, when a vanadium dioxide thin film composed of a VO ₂ phase exhibiting thermochromic properties is formed on a substrate that requires low temperature film formation in the range of room temperature to 100 ° C., such as a PET film, a magnesium oxide thin film It has been shown that an oxide thin film containing magnesium and zinc or an oxide thin film containing magnesium and zinc and gallium and / or aluminum is extremely useful as a base film.

(Evaluation of transmittance)
Next, according to FIG. 4, the base films of Examples 32 to 35 are formed on the oxide thin film obtained by adding zinc and gallium to magnesium oxide, the vanadium dioxide thin film formed on the base film, and the vanadium dioxide thin film. The transmittance of the thermochromic body having a three-layer laminated film structure made of the silicon oxide thin film and the vanadium dioxide thin film directly formed on the Corning 7059 glass substrate of Comparative Example 7 is compared.

At a wavelength lambda ₀ = 300 nm, the optical film thickness lambda _0/4 of the base film, an optical film thickness of lambda _0/2 of the vanadium dioxide thin film, thermochromic of which Example 32 is an optical thickness lambda _0/4 of the silicon oxide thin film It can be seen that the body has a higher visible light transmittance than the thermochromic body having only the vanadium dioxide thin film of Comparative Example 7. From this, it can be seen that a thermochromic body having a three-layer laminated film structure using a base film containing magnesium oxide is useful in that the visible light transmittance is high.

Also, thermochromic material, the optical thickness of the base film _{λ 1/4 (λ 1 =} 500nm) of the optical film thickness of the silicon oxide thin film _{λ 3/4 (λ 3 =} 500nm) considerably thickened Example 33 corresponds thermochromic of thickened example 34 in body, the base film and the optical film thickness of the silicon oxide thin film _{λ 1/4 (λ 1 =} 500nm) and _{λ 3/4 (λ 3 =} 500nm) considerably thickened example 35 In the thermochromic body, visible light transmittance was further improved as compared with the thermochromic body of Example 32. That is, the film thickness of the first layer and / or the third layer, by thicker than lambda _0/4, was confirmed to be improved further visible light transmittance.

Even when the three-layer laminated film structure is changed in this way, as can be seen from the thermochromic characteristic evaluation shown in FIG. 4, there is no significant change in the index ΔT ₁₅₀₀ , and the visible light transmittance improvement effect is large. confirmed. Thus, the thermochromic material of three-layer film structure using a base film containing magnesium oxide base film and / or a silicon oxide film was thicker than lambda _0/4 structure was found to be useful.

  1, 2 Thermochromic body, 10 substrate, 11 base film, 12 vanadium dioxide thin film, 13 silicon oxide thin film

Claims (12)

A base film comprising a magnesium oxide thin film formed on a substrate or an oxide thin film obtained by adding zinc to magnesium oxide;
A thermochromic body comprising: a vanadium dioxide thin film formed on the base film.   2. The thermochromic body according to claim 1, wherein a magnesium addition amount of the base film is 0.01 to 1.0 in terms of a magnesium atom number ratio represented by Mg / (Mg + Zn). The base film is made of an oxide thin film obtained by adding zinc to magnesium oxide,
3. The thermochromic body according to claim 1, wherein a magnesium addition amount of the base film is 0.01 to 0.18 in terms of a magnesium atom number ratio represented by Mg / (Mg + Zn). The base film is obtained by further adding aluminum and / or gallium to an oxide thin film obtained by adding zinc to magnesium oxide.
The magnesium addition amount is 0.01 to 0.18 in terms of the number of magnesium atoms represented by Mg / (Mg + Zn + Al + Ga), and the number ratio of aluminum and / or gallium represented by (Al + Ga) / (Mg + Zn + Al + Ga) The thermochromic body according to claim 1, wherein the thermochromic body is 0.05 or less.   The thermochromic body according to any one of claims 1 to 4, further comprising a silicon oxide thin film on the vanadium dioxide thin film. At a wavelength lambda _0, wherein the optical thickness of the base film λ _0/4, the vanadium dioxide based optical thickness of the thin film λ _0/2, that the optical thickness of the silicon oxide thin film and lambda _0/4 The thermochromic body according to claim 5, wherein the thermochromic body is characterized. When the wavelength λ ₀ is 200 to 400 nm, and the wavelength λ ₃ is in the range of 700 nm or less exceeding the λ ₀ ,
Claim the underlayer optical thickness lambda _0/4 of the optical thickness of the vanadium dioxide-based thin film lambda _0/2, which is characterized in that the optical thickness of the silicon oxide thin film and lambda _3/4 5. The thermochromic body according to 5. When the wavelength λ ₀ is 200 to 400 nm and the wavelength λ ₁ is in the range of 700 nm or less exceeding the λ ₀ ,
Claim the underlayer optical thickness lambda _1/4 of the optical thickness of the vanadium dioxide-based thin film lambda _0/2, which is characterized in that the optical thickness of the silicon oxide thin film and lambda _0/4 5. The thermochromic body according to 5. When the wavelength λ ₀ is 200 to 400 nm, and the wavelengths λ ₁ and λ ₃ are in the range of 700 nm or less exceeding the λ ₀ ,
Claim the underlayer optical thickness lambda _1/4 of the optical thickness of the vanadium dioxide-based thin film lambda _0/2, which is characterized in that the optical thickness of the silicon oxide thin film and lambda _3/4 5. The thermochromic body according to 5.   The heat ray shielding glass which consists of a thermochromic body of any one of Claims 1 thru | or 9.   The heat ray shielding film which consists of a thermochromic body of any one of Claims 1 thru | or 9.   A method for producing a thermochromic body, characterized in that a magnesium oxide thin film or an oxide thin film obtained by adding zinc to magnesium oxide is formed as a base film on a substrate, and a vanadium dioxide thin film is formed on the base film.

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