JP2014097920A - Zinc oxide-based powder and method for producing zinc oxide-based sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide zinc oxide-based powder capable of achieving hot isostatic pressure sintering in which the volatilization of zinc is suppressed, and capable of producing a sintered compact having high density, a method for producing a zinc oxide-based sintered compact, and a target.SOLUTION: Provided is zinc oxide-based powder having a tap density of 2.8 g/cmor higher obtained by mixing titanium carbide powder and fired zinc oxide powder having a tap density of 2.8 g/cmor higher. The fired zinc oxide powder containing the titanium carbide in such a manner that the ratio of the atomic number of titanium to the total metal atomic number reaches 0.2 to 5%, and having a tap density of 2.8 g/cmis obtained by firing raw material zinc oxide powder having a tap density of less than 2.8 g/cm.

Description

  The present invention relates to a zinc oxide-based powder useful for stably forming a zinc oxide-based transparent conductive film by sputtering or the like, a method for producing a zinc oxide-based sintered body, and a target using them.

  A transparent conductive film is a film having both visible light transmission and electrical conductivity, electrodes for solar cells, liquid crystal display elements, light receiving elements, etc .; heat ray reflective films for automobile windows, buildings, etc .; antistatic films; refrigeration It is used in a wide range of fields such as a transparent heating element for defogging in showcases. In particular, it is known that a transparent conductive film having low resistance and excellent conductivity is suitable for a solar cell, a liquid crystal display element (liquid crystal, organic electroluminescence, inorganic electroluminescence, etc.), a touch panel, and the like.

Conventionally, an ITO film obtained by adding tin oxide to indium oxide has been used as the transparent conductive film. However, since indium as a raw material is a rare metal and there are problems in the amount of resources, price, and the like, a film that replaces the ITO film is required.
For example, a zinc oxide-based transparent conductive film that can be industrially manufactured by a sputtering method has attracted attention, and research is being conducted to improve its conductive performance. Specifically, Non-Patent Document 1 reports an attempt to dope various dopants into ZnO in order to increase conductivity. Among them, AZO (aluminum-doped zinc oxide) and GZO (gallium-doped zinc oxide) are currently used practically because they exhibit excellent conductivity. However, it is inferior in chemical durability and is mainly used for the transparent conductive film for solar cells that is currently used. Particularly, since the transparency in the near infrared region is low, the conversion efficiency of the solar cell is greatly reduced. There is a problem.

In addition, the present inventor has excellent chemical durability compared to zinc, and if low-valent titanium oxide is used instead of tetravalent titanium oxide (TiO ₂ (IV)) as a titanium source as a dopant, chemical durability is achieved. It has been found that the content of titanium useful for improving the properties can be increased. Furthermore, it has been found that it has low resistance and excellent near-infrared transmittance that is promising for transparent conductive films such as solar cells (see Patent Document 1).
By the way, low-valent titanium oxide typified by TiO (II) is not widely used unlike TiO ₂ (IV) used for photocatalysts, pigments, and the like, and its cost increases when used. Therefore, there is no problem when the transparent conductive film is used for a special purpose that does not cause a problem in terms of cost. However, when the transparent conductive film is used for a general purpose, the cost may be disadvantageous. is there.

In addition to the low-valence titanium oxide that the present inventors have already found as a titanium source, it is considered that titanium boride and metal titanium as described in Patent Document 2 may exhibit similar characteristics. Although not a titanium source, it is considered that a large amount of oxygen deficiency can be introduced by introducing zinc or aluminum, which is a constituent element of the zinc oxide-based transparent conductive film, in the form of metallic zinc or metallic aluminum. .
However, when titanium boride is used, boron oxide is generated during sintering. This boron oxide has a low melting point and low boiling point (melting point: about 450 ° C., boiling point: about 1860 ° C.), and at a sintering temperature (at least 1000 ° C.) necessary for obtaining a sintered body having the required minimum density, It is easy to melt and evaporate. Therefore, it becomes a sintered body having a non-uniform composition and a low density, and is inappropriate for use as a transparent conductive film forming material.

On the other hand, for titanium metal, there are no primary particles having an average particle size of 1 μm or less necessary for obtaining a uniform and high-density sintered body. That is, for commercially available titanium metal, the minimum primary particle size is about 20 μm, and pulverizing this to a particle size of about several μm may cause a dust explosion and ignite. Primary particles having an average particle size of 1 μm or less cannot be obtained.
When metallic zinc or metallic aluminum is introduced, metallic zinc (melting point: 419 ° C., boiling point: 930 ° C.) and metallic aluminum (melting point: 660 ° C., boiling point: 2060 ° C.) have a low melting point and boiling point and are melted. Evaporates easily. Therefore, a porous sintered body having a low sintered density is obtained, or the molten metal flows and segregates (uneven composition).

It is also conceivable to use titanium carbide as the titanium source. In this case, in order to suppress the oxidation of titanium carbide to titanium oxide (TiO ₂ ), it is necessary to sinter in a non-oxidizing atmosphere (inert atmosphere, reducing atmosphere, etc.) in pressureless sintering. However, when sintered in a non-oxidizing atmosphere, zinc oxide becomes metal zinc that is easily reduced and more easily volatilized. Therefore, when manufacturing a sintered body in a non-oxidizing atmosphere, it is manufactured in an oxidizing atmosphere. The amount of zinc disappeared more than in the case. Thus, suppression of zinc volatilization cannot be physically realized by pressureless sintering.
In the portion where zinc has been volatilized, voids are likely to be generated, leading to a decrease in the density of the sintered body. When a film is formed by sputtering using such a low-density sintered body, abnormal discharge is likely to occur, and there is a problem that the film cannot be stably formed.

In the case of pressure sintering, there is a possibility that the volatilization of zinc can be suppressed. However, in a general hot press method, raw material powder is molded and pressed and sintered. However, since there is a clearance (gap) between the graphite die and the punch, zinc is slightly evaporated from the clearance. Further, when a normal hot isostatic pressing (HIP) method (so-called capsule-free HIP method) is employed, the bulk sintered body can be further densified.
However, the capsule-free HIP method uses, as a raw material, a sintered body that has been densified to some extent (relative density is 90 to 95%) (there are only closed pores whose defects are blocked from the appearance). Furthermore, the closed pores cannot be crushed and densified. Therefore, in order to obtain a sintered body having a certain degree of density, a sintering step is separately required in advance, and zinc is volatilized in this sintering step.

Therefore, as a sintering method that does not require a separate sintering step and can obtain a high-density sintered body by suppressing the volatilization of zinc, the raw material powder is filled into a metal container (capsule), There is a capsule hot isostatic pressing (capsule HIP) method in which sealing is performed and pressure sintering is performed.
Capsule HIP is the only method that can suppress the volatilization of zinc to almost zero because the powder to be sintered (raw material powder) is hermetically sealed in a metal container. However, since the capsule HIP is subjected to pressurization together with the metal container, when the shrinkage rate of the metal container due to pressurization is large (that is, when the filling rate of the raw material powder is low), the metal container bursts. When the metal container bursts, the raw material powder is scattered and a sintered body cannot be obtained.

  By the way, when using commercially available zinc oxide powder as the main raw material of the raw material powder, the filling rate is only about 20% at the highest. When performing capsule HIP, since it is generally necessary to make the filling rate of the raw material powder filled in the metal container at least 50%, a commercially available zinc oxide powder cannot be used as the raw material powder as it is.

JP 2011-190528 A Patent No. 4984423

Monthly Display, September 1999, p10 “Trends in ZnO-based transparent conductive films”

  An object of the present invention is to suppress the zinc volatilization and to produce a high-density sintered body. The zinc oxide-based powder that can realize hot isostatic pressing of capsules and can be practically used. An object of the present invention is to provide a method for producing a zinc oxide-based sintered body and a target capable of forming a transparent conductive film having conductivity, excellent chemical durability, and high near-infrared transmittance.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) and the titanium carbide powder, obtained by mixing the calcined zinc oxide powder having a 2.8 g / cm ³ or more tap density, a zinc oxide-based powder having a 2.8 g / cm ³ or more tap density The titanium carbide powder is contained so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less, and has a tap density of 2.8 g / cm ³ or more. calcined zinc oxide powder, 2.8 g / cm ³ less than the raw material of zinc oxide powder having a tap density by firing, characterized in that it is obtained by, zinc oxide-based powder having a 2.8 g / cm ³ or more tap density .
(2) At least one selected from the group consisting of gallium oxide powder, aluminum oxide powder and aluminum carbide powder has a ratio of the number of atoms of gallium or aluminum of 0.1% or more to the total number of metal atoms. The zinc oxide-based powder according to (1), further contained so as to be 5% or less.
(3) and titanium carbide powder, obtained by calcining a mixture of raw material zinc oxide powder having a tap density less than 2.8 g / cm ^3, a zinc oxide-based powder having a 2.8 g / cm ³ or more tap density The titanium carbide powder is contained such that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less, 2.8 g / cm ^A zinc oxide-based powder having a tap density of ³ or more.
(4) When the mixture is at least one selected from the group consisting of gallium oxide powder, aluminum oxide powder, and aluminum carbide powder, the ratio of the number of gallium or aluminum atoms to the total number of metal atoms is 0.1. The zinc oxide-based powder according to (3), further contained so as to be not less than 2.5% and not more than 2.5%.
(5) The zinc oxide-based powder according to (1) or (2), wherein the firing is performed at 900 to 1400 ° C. in an oxidizing atmosphere.
(6) The zinc oxide-based powder according to any one of (1) to (4), wherein the firing is performed at 900 to 1300 ° C. in a non-oxidizing atmosphere.
(7) The zinc oxide-based powder according to any one of (1) to (6), wherein the raw material zinc oxide powder has a tap density of 0.5 to 1.2 g / cm ³ .
(8) A zinc oxide-based sintered body including a step of filling a metal container with the zinc oxide-based powder according to any one of (1) to (7) and performing capsule hot isostatic pressing sintering Manufacturing method.
(9) The production method according to (8), wherein a sintering temperature in the capsule hot isostatic pressing is 900 to 1400 ° C., and a relative density of the sintered body is 98% or more.
(10) The manufacturing method according to (8) or (9), wherein the capsule hot isostatic pressing is performed in an inert gas atmosphere.
(11) The manufacturing method according to any one of (8) to (10), wherein the capsule hot isostatic pressing is performed under a pressure condition of 50 MPa or more.
(12) A target used for film formation by a sputtering method, an ion plating method, a pulse laser deposition (PLD) method, or an electron beam (EB) vapor deposition method, which is described in any one of (8) to (11) A target obtained by processing a zinc oxide-based sintered body obtained by the above manufacturing method.

According to the present invention, since the tap density of the zinc oxide-based powder is 2.8 g / cm ³ or more, the zinc oxide-based powder is filled in a metal container, and the filling rate of the zinc oxide-based powder is 50% or more. It can be. Therefore, even if capsule hot isostatic pressing is performed, the metal container does not rupture, the volatilization of zinc is suppressed, and the composition of the raw material zinc oxide powder and the composition of the sintered body are almost the same. A high-density zinc oxide-based sintered body can be obtained. By using this zinc oxide-based sintered body, it is possible to form a film stably and with good reproducibility with almost no abnormal discharge occurring during film formation. The obtained transparent conductive film has conductivity that can withstand practical use, excellent chemical durability, and high near-infrared transmittance. Furthermore, since expensive indium and low-valent titanium oxide are not used, significant cost reduction is possible, and it has the advantage of not requiring rare metals and toxic indium, so it is extremely useful industrially. It is.

(A) is the SEM photograph (magnification: 10 times) of the zinc oxide powder (baked zinc oxide powder) after baking in Example 1, (b) is the SEM photograph (magnification: 5000) which changed the magnification of (a). Times). (A) is a SEM photograph (magnification: 5000 times) of the zinc oxide powder before firing in Example 1, and (b) is an SEM photograph (magnification: 30000 times) with the magnification of (a) changed.

(Zinc oxide powder)
Zinc oxide-based powder according to the present invention, the titanium carbide powder, obtained by mixing the calcined zinc oxide powder having a 2.8 g / cm ³ or more tap density, the 2.8 g / cm ³ or more tap density The titanium carbide powder contains the titanium carbide powder so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less, and the 2.8 g / cm ³ The fired zinc oxide powder having the above tap density is obtained by firing the raw material zinc oxide powder having a tap density of less than 2.8 g / cm ³ . Hereinafter, this zinc oxide-based powder may be referred to as “zinc oxide-based powder according to the first embodiment”.

The titanium carbide powder is not particularly limited, but preferably has a purity of 99% by mass or more. For example, commercially available titanium carbide powder is used. The average particle diameter of the titanium carbide powder is not particularly limited, but is preferably 0.02 μm or more and 5 μm or less. In the case of titanium carbide powder having a large particle size, it may be used after being pulverized. The BET specific surface area is not particularly limited.
The titanium carbide powder usually has a tap density of about 1.6 to 1.8 g / cm ³ . The content of the titanium carbide powder is small as will be described later, and has almost no influence on the tap density of the resulting zinc oxide-based powder, so the tap density of the titanium carbide powder is not particularly limited.

As described above, the present inventors have found that using low-valent titanium oxide (for example, TiO (II)) as a titanium source is effective for reducing the resistance. When low-valent titanium oxide is used, it is presumed that oxygen vacancies can be stably introduced in a large amount into the sintered body, and carrier electrons derived from oxygen vacancies contribute to conductivity. Titanium carbide has carbon in the molecule, and this carbon captures oxygen present in the raw material during sintering and releases it out of the system as CO or CO _2. A deficient state can be introduced.
Furthermore, during film formation in sputtering, a trace amount of oxygen in the chamber adversely affects plasma discharge stability. Titanium carbide removes a small amount of oxygen in the chamber because carbon in the molecule captures a small amount of adsorbed oxygen in the chamber (reducing adsorbed oxygen) and releases it as CO or CO ₂ to the outside of the system. Also fulfills.

In the zinc oxide-based powder according to the first embodiment, titanium carbide is contained so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less. When titanium carbide is contained in such a proportion, zinc atoms do not volatilize even when baked by a capsule hot isostatic pressing method (hereinafter sometimes referred to as “capsule HIP method”). A zinc oxide-based sintered body having a composition in which the number ratio is within this range can be produced. When a film is formed using such a zinc oxide-based sintered body, a transparent conductive film having excellent chemical durability, conductivity and transparency can be obtained.
In the zinc oxide-based powder according to the first embodiment, the titanium carbide has a ratio of the number of titanium atoms to the total number of metal atoms, preferably 0.5 to 4.0%, more preferably 0.7 to It is contained so as to be 3.5%.

Raw zinc oxide powder, as described above, has a tap density of less than 2.8 g / cm ^3, preferably 0.5 to 1.2 g / cm ^3. Commercially available zinc oxide powders have a tap density of 1.12 g / cm ³ or less, although there are some differences depending on the particle size and particle size distribution. If the tap density is less than 2.8 g / cm ³ , the raw material zinc oxide powder may have a firing history. In addition, the theoretical density (upper limit of tap density) of zinc oxide is 5.6 g / cm ³ .
The tap density in the present invention is based on JIS K5101. After filling a container with a certain volume with powder by natural dropping, the container is further subjected to a constant vibration (tapping), and the volume change of the powder is eliminated. It is defined as the mass of the powder per unit volume. Note that the powder mass per unit volume when the container is filled with powder by a natural drop and the inner volume is the volume is called the bulk density. Generally, the tap density is 1% of the bulk density. The value is about 1 to 1.3 times.

As the raw material zinc oxide powder, a powder such as ZnO having a wurtzite structure is usually used, and further, this ZnO may be previously fired in an inert atmosphere or a reducing atmosphere to generate oxygen deficiency. The purity of the raw material zinc oxide powder is not particularly limited, and for example, a material having a purity of 99% by mass or more is preferable.
The average particle diameter of the raw material zinc oxide powder is not particularly limited, and is preferably 0.02 μm or more and 5 μm or less, for example. The BET specific surface area is not particularly limited.

The fired zinc oxide powder having a tap density of 2.8 g / cm ³ or more used in the present invention is obtained by firing the raw material zinc oxide powder. For example, the raw zinc oxide powder may be baked and then pulverized into a powder by a known method such as a George crusher, a roll crusher, a stamp mill, a hammer mill, or a mortar.

The firing conditions of the raw material zinc oxide powder are not particularly limited. The firing temperature is usually about 900 to 1400 ° C. When the firing temperature is within this range, the zinc oxide is reduced and the metal zinc is not precipitated or the zinc is not volatilized, so that the grain growth can sufficiently proceed and 2.8 g / cm ³ or more. A calcined zinc oxide powder having a tap density of is obtained. The apparatus used for baking is not specifically limited, A vertical electric furnace, a tubular furnace, a muffle furnace, a tube furnace, a hearth raising / lowering electric furnace, a box type electric furnace, etc. are mentioned.

  The firing time is usually about 8 to 24 hours, preferably about 10 to 15 hours. If the firing time is less than 8 hours, sintering may be insufficient and the tap density may not be improved. On the other hand, even if the firing time exceeds 24 hours, the tap density is not further improved, which is not preferable in terms of cost.

If the firing temperature and firing time are within such ranges, zinc oxide can be prevented from pyrolysis and volatilization, grain growth can be sufficiently advanced, and the tap density is 2.8 g / cm ^3. As mentioned above, it can be set as the zinc oxide type powder which is 3.3-5.6 g / cm < ³ > normally. In particular, the firing temperature is preferably as high as possible within the above range, and solid-phase sintering proceeds between the particles, grain growth occurs, and the particle size increases on average. As a result, since the particle size distribution becomes wide, small particles enter the gaps between the large particles, and when the particles are filled, the gaps between the particles per unit volume are reduced, leading to an improvement in tap density.

The atmosphere at the time of firing may be an oxidizing atmosphere (eg, air atmosphere, oxidizing atmosphere, etc.) or a non-oxidizing atmosphere (eg, inert atmosphere, reducing atmosphere, vacuum, etc.). It is preferable to bake in.
Firing is preferably performed at 900 to 1400 ° C., more preferably 1000 to 1300 ° C. in an oxidizing atmosphere, and preferably 900 to 1300 ° C., more preferably 920 to 1200 ° C. in a non-oxidizing atmosphere. Is called.

Examples of the oxidizing atmosphere include an atmosphere having a higher oxygen concentration than the air.
As an inert atmosphere, atmospheres, such as nitrogen, argon, helium, neon, a carbon dioxide, are mentioned, for example.
Examples of the reducing atmosphere include hydrogen, carbon monoxide, hydrogen sulfide, sulfur dioxide, and the like.

Firing the zinc oxide powder obtained in this way, 2.8 g / cm ³ or more, preferably a tap density of 3.3~5.6g / cm ^3. A large amount of the zinc oxide powder obtained by mixing the calcined zinc oxide powder and the titanium carbide powder (the zinc oxide powder according to the first embodiment) is filled in a metal container. % Or more. In particular, when the zinc oxide powder has a tap density of 3.3 to 5.6 g / cm ³ , more powder can be filled, and the metal container after capsule HIP sintering contracts symmetrically. This makes it easier to process.

Furthermore, since the filling rate can be 50% or more, the shrinkage rate of the metal container by the capsule HIP method can be 50% or less. Therefore, the zinc oxide powder can be sintered under pressure without destroying the metal container, and a high-density zinc oxide sintered body that suppresses volatilization of zinc derived from the raw material zinc oxide powder can be obtained.
Here, the filling rate is theoretically assumed that the sintered body has reached the theoretical density after the capsule HIP, and the tap density of the zinc oxide-based powder that is the raw material of the sintered body with respect to the theoretical density of the obtained sintered body. Is the ratio.

Moreover, the shrinkage rate of the metal container is obtained using the following formula.
Shrinkage ratio (%) of metal container = [1− (inner volume of metal container after capsule HIP / inner volume of metal container before capsule HIP)] × 100

  The zinc oxide-based powder according to the first embodiment has at least one selected from the group consisting of gallium oxide powder, aluminum oxide powder and aluminum carbide powder for the purpose of further reducing resistance (hereinafter referred to as “gallium oxide powder”). May be abbreviated as “, etc.”).

The gallium oxide (Ga ₂ O ₃ ) powder, aluminum oxide (Al ₂ O ₃ ) powder, and aluminum carbide (Al ₄ C ₃ ) powder preferably have a purity of 99% by mass or more. For example, commercially available products are used. Is done. The average particle diameter of the gallium oxide powder or the like is not particularly limited, but is preferably 5 μm or less. In addition, since content of gallium oxide powder etc. is a small amount as will be described later and does not substantially affect the tap density of the obtained zinc oxide powder, the tap density of gallium oxide powder etc. is not particularly limited.
At least one selected from the group consisting of gallium oxide powder, aluminum oxide powder and aluminum carbide powder is contained so that the ratio of the number of atoms of gallium or aluminum is 0.1% or more and 2.5% or less. Preferably it is 0.3 to 2.3%, more preferably 0.5 to 2%.

  When the ratio of the number of atoms of gallium or aluminum is less than 0.1%, the effect of improving conductivity is insufficient. On the other hand, when it exceeds 2.5%, gallium or aluminum cannot be completely substituted and dissolved in the zinc site, and precipitates at the crystal grain boundary, leading to a decrease in conductivity or a decrease in transmittance. Two or more kinds of gallium oxide powder, aluminum oxide powder and aluminum carbide powder may be used in combination, and in that case, the total amount may be 0.1% or more and 2.5% or less.

  The mixing method of the titanium carbide powder and the specific calcined zinc oxide powder may be wet mixing or dry mixing. Specifically, the mixing is performed using a pow mixer, a Hensiel mixer, a Nauter mixer, a ribbon mixer, a uniaxial stirrer, a biaxial stirrer, or the like.

As described above, the zinc oxide-based powder according to the first embodiment includes titanium carbide, a specific calcined zinc oxide powder obtained by calcining a raw material zinc oxide powder in advance, and a gallium oxide powder or an oxidation as required. It is obtained by mixing with aluminum powder.
By the way, the zinc oxide-based powder of the present invention can also be obtained by firing a mixture of titanium carbide, raw material zinc oxide powder and, if necessary, gallium oxide powder.

That is, another zinc oxide-based powder according to the present invention is 2.8 g / cm obtained by firing a mixture of titanium carbide powder and raw material zinc oxide powder having a tap density of less than 2.8 g / cm ^{3. It} is a zinc oxide powder having a tap density of ³ or more, and the titanium carbide powder is contained so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less. Hereinafter, this zinc oxide-based powder may be referred to as “zinc oxide-based powder according to the second embodiment”.
To the zinc oxide powder according to the second embodiment, at least one selected from the group consisting of gallium oxide powder, aluminum oxide powder, and aluminum carbide powder may be added for the purpose of further reducing resistance.

The titanium carbide powder used for the zinc oxide powder according to the second embodiment, the raw material zinc oxide powder, and the gallium oxide powder used as necessary are as described above.
The zinc oxide-based powder according to the second embodiment is obtained by mixing these powders by the above-described wet mixing or dry mixing and firing the resulting mixture. In particular, in the second embodiment, firing is preferably performed in the non-oxidizing atmosphere described above. This is because titanium carbide is oxidized to titanium oxide when firing is performed in an oxidizing atmosphere. The obtained sintered body may be pulverized into a powder by a known method such as a George crusher, a roll crusher, a stamp mill, a hammer mill, or a mortar.

  Even when the zinc oxide powder according to the second embodiment is fired by the capsule HIP method, the zinc oxide does not volatilize and a zinc oxide sintered body having a composition in which the ratio of the number of titanium atoms is within this range is manufactured. can do. When a film is formed using such a zinc oxide-based sintered body, a transparent conductive film having excellent chemical durability, conductivity and transparency can be obtained.

(Method for producing zinc oxide-based sintered body)
The method for producing a zinc oxide-based sintered body according to the present invention includes filling a metal container with the above-described zinc oxide-based powder (zinc oxide-based powder according to the first or second embodiment), and then performing hot capsules, etc. This is a method for producing a zinc oxide-based sintered body by performing one-way pressurization (capsule HIP) sintering. Since this capsule HIP sintering is performed by filling zinc oxide powder in a closed space (that is, filling a metal container by vacuum sealing), zinc volatilization is suppressed, and the resulting zinc oxide system is obtained. It is possible to obtain a high-density zinc oxide-based sintered body in which composition deviation hardly occurs between the sintered body and the charged zinc oxide-based powder.

The metal container may be any material that can be vacuum-sealed and does not rupture even when sufficiently deformed at the sintering temperature, and iron, aluminum, stainless steel, etc. are usually used.
The metal container preferably has a wall thickness of 1.5 mm to 4 mm. Within this range, the metal container can be easily softened and deformed, and can shrink following the sintered body as the sintering reaction proceeds. The shape of the metal container is not particularly limited, and may be any shape that is easily isotropically pressurized during capsule HIP sintering, and examples thereof include a cylindrical shape and a rectangular parallelepiped shape. The dimensions of the metal container are appropriately set depending on the desired size of the zinc oxide sintered body.

When performing capsule HIP, after filling a metal container with a zinc oxide powder having a tap density of 2.8 g / cm ³ or more, the pressure in the metal container is 1.33 while heating the metal container. The pressure is reduced until the pressure becomes 10 ⁻² Pa or less (evacuation is performed). Thereby, gas, adsorbed moisture, etc. adhering to the zinc oxide-based powder can be removed. Unless the pressure is reduced to 1.33 × 10 ⁻² Pa or less, the removal of gas, adsorbed moisture, etc. adhering to the zinc oxide powder will be insufficient, the metal container will swell during sintering, and high density firing will occur. There is a possibility that a ligation cannot be obtained.
The decompression is performed, for example, by connecting an exhaust pipe to a metal container. When the pressure in the metal container becomes 1.33 × 10 ⁻² Pa or less, the exhaust pipe is closed and the metal container is sealed. During the decompression, the metal container is preferably heated to about 100 to 600 ° C.

  Capsule HIP processing (capsule HIP sintering) is performed by placing a metal container in the HIP apparatus. Capsule HIP treatment is to sinter zinc oxide-based powder inside a metal container using gas under high temperature and high pressure as a pressure medium.

The treatment temperature (sintering temperature) is preferably 900 to 1400 ° C, more preferably 1000 to 1300 ° C. If the temperature is within such a temperature range, the metal container is in a temperature range where the metal container is softened and deformed. Therefore, during the capsule HIP process, the metal capsule does not become a resistance and pressure is applied to the zinc oxide powder in the metal container. 100%.
The gas used for a pressure medium is not specifically limited, For example, inert gas, such as nitrogen and argon, is mentioned. The treatment pressure is preferably 50 MPa or more, more preferably 70 MPa or more, and the treatment time is preferably 1 hour or more, more preferably 1.5 hours or more.
If the processing temperature is too low, the pressure is too low, or the time is too short, a sintered body having a low relative density (for example, less than 90%) tends to be obtained.

When the treatment is performed under such temperature conditions, a zinc oxide-based sintered body having a relative density of 98% or more is obtained. When such a zinc oxide-based sintered body is used, for example, when forming a film by sputtering, abnormal discharge hardly occurs and the film can be stably formed.
Here, the relative density is obtained by multiplying the unit density of each metal oxide, which is a raw material of the sintered body, by the mixing weight ratio of each metal oxide powder, and the actual density obtained by taking the sum of the theoretical density. For example, when the sintered body is made of zinc oxide and titanium carbide, the density is obtained from the following formula.
Relative density = [(density of sintered body) / (theoretical density)] × 100
Theoretical density = (Zinc oxide simple substance density x mixing mass ratio) + (Titanium carbide simple substance density x mixing mass ratio)
In addition, the density of a sintered compact can be measured with the evaluation method as described in an Example.

  The zinc oxide-based sintered body thus obtained is substantially composed of zinc, oxygen, titanium, carbon, and optionally gallium or aluminum. Here, “substantially” means that 99% or more of all atoms constituting the oxide sintered body are composed of zinc, oxygen, titanium, carbon, and optionally gallium or aluminum. To do.

If the zinc oxide-based sintered body is substantially composed of zinc, oxygen, titanium, carbon, and, if necessary, aluminum or gallium, tin, silicon, germanium, zirconium, hafnium, indium, It may contain at least one selected from the group consisting of iridium, ruthenium and rhenium.
The trace atom may be, for example, an impurity mixed in the raw material powder, or an oxide of a trace element may be further added as the raw material powder.

The additive element may be present in the zinc oxide-based sintered body in the form of an oxide, or may be present in the form substituted (solid solution) in the zinc site of the zinc oxide phase, or titanium. It may exist in a form substituted (solid solution) with at least one selected from a titanium site and a zinc site in the zinc acid compound phase.
In addition, the zinc oxide phase specifically includes ZnO, a solution in which a titanium element is dissolved, an oxygen deficiency introduced, or a non-stoichiometric composition due to zinc deficiency. Including things. The zinc oxide phase usually has a wurtzite structure.

The zinc titanate compound phase specifically includes ZnTiO ₃ , Zn ₂ TiO ₄ , those in which a titanium element is dissolved in these zinc sites, those in which oxygen vacancies are introduced, Non-stoichiometric compositions with a Zn / Ti ratio slightly deviating from these compounds are also included.

Since the zinc oxide-based sintered body is obtained by the capsule HIP method described above, the ratio of the number of atoms such as titanium and gallium is the same as that of the zinc oxide-based powder of the present invention to be used. That is, the ratio of the number of titanium atoms is 0.2% to 5% with respect to the total number of metal atoms, and the ratio of the number of gallium or aluminum atoms used as necessary is 0 with respect to the total number of metal atoms. .1% or more and 6% or less.
When such a zinc oxide-based sintered body is used, it has chemical durability far superior to currently used AZO (aluminum-doped zinc oxide) and GZO (gallium-doped zinc oxide), and has conductivity and A transparent conductive film having transparency is obtained.

In particular, when the content of titanium is smaller within the above range (in the case of about 0.2% to 2%), the refractive index of the formed film becomes small, while maintaining high transmittance in the near infrared region, The transmittance from the near ultraviolet light region to the visible light region tends to increase. When the transparency of the film from the near ultraviolet light region to the visible light region is improved, the conversion efficiency of the solar cell using this transparent conductive film can be increased.
As described above, the characteristics can be freely adjusted depending on the use requiring extremely high chemical durability and the use requiring high transparency in the near ultraviolet light region to the visible light region.

It is preferable that the zinc oxide-based sintered body does not substantially contain a titanium carbide crystal phase. If the zinc oxide-based sintered body contains a crystal phase of titanium carbide, the resulting film may be uneven in physical properties such as specific resistance and lack uniformity. In the zinc oxide-based sintered body, since the ratio of the number of titanium atoms is 0.2% or more and 5% or less with respect to the total number of metal atoms, usually the titanium completely reacts with the zinc oxide and the zinc oxide-based sintered body. Titanium carbide crystal phase is difficult to be formed in the bonded body.
The crystal phase of titanium carbide specifically includes titanium carbide and substances obtained by dissolving other elements such as zinc in these crystals.

The zinc oxide-based sintered body obtained from the zinc oxide-based powder using titanium carbide and zinc oxide is preferably a sintered body composed of a zinc oxide phase and a zinc titanate compound phase. When the zinc titanate compound phase is contained in the zinc oxide-based sintered body as described above, the strength of the sintered body increases. For example, when a film is formed, it is formed under severe conditions (high power, etc.). Even if the film is formed, no cracks are generated. The zinc titanate compound phase and the zinc oxide phase are as described above.
A zinc oxide-based sintered body obtained from a zinc oxide-based powder further using gallium oxide powder or the like includes a zinc oxide phase, a zinc titanate compound phase, and at least one oxide phase selected from gallium and aluminum. A sintered body composed of a zinc oxide phase and a zinc titanate compound phase; a sintered body composed of a zinc titanate compound phase is preferable.

  The zinc oxide-based sintered body preferably has a specific resistance of 5 kΩ · cm or less. For example, the deposition rate during DC sputtering depends on the specific resistance of the zinc oxide-based sintered body used as a sputtering target. Therefore, when the specific resistance of the zinc oxide-based sintered body exceeds 5 kΩ · cm, the DC sputtering is stable There is a possibility that the film cannot be formed. Considering the productivity at the time of film formation, the specific resistance of the zinc oxide-based sintered body is preferably as low as possible. Specifically, it should be 100 Ω · cm or less.

  The zinc oxide-based sintered body is preferably obtained by the method for producing a zinc oxide-based sintered body according to the present invention. However, it is not limited to those obtained by this manufacturing method. Normally, when a zinc oxide-based sintered body is sintered in a reducing atmosphere, the specific resistance of the zinc oxide-based sintered body is reduced due to the introduction of oxygen deficiency, and when sintered in an oxidizing atmosphere, the specific resistance is reduced. Becomes higher.

(target)
The target of the present invention is a target used in various film forming methods, and in particular, a target used for film forming by sputtering, ion plating, pulse laser deposition (PLD), or electron beam (EB) vapor deposition. It is. The target of the present invention is obtained by processing the zinc oxide-based sintered body obtained by the above production method. Therefore, the target of the present invention has a high density. For example, when a film is formed by a sputtering method, abnormal discharge hardly occurs and the film can be stably formed. In addition, although the solid material used in the film formation may be referred to as “tablet”, in the present invention, these are referred to as “target”. The target of the present invention is obtained by processing the above-described zinc oxide-based sintered body of the present invention into a predetermined shape and a predetermined dimension.

A processing method in particular is not restrict | limited, What is necessary is just to employ | adopt a well-known method suitably. For example, after subjecting the zinc oxide-based sintered body to surface grinding or the like, the target of the present invention can be obtained by cutting the zinc oxide-based sintered body into a predetermined size and sticking it to a support base. If necessary, a plurality of zinc oxide-based sintered bodies may be arranged in a divided shape to form a large area target (composite target).
The transparent conductive film formed using the target of the present invention has both excellent conductivity and chemical durability (heat resistance, moisture resistance, etc.) stably with good reproducibility. Therefore, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic paper; window electrodes of photoelectric conversion elements of solar cells; electrodes of input devices such as transparent touch panels; It can be used in combination with other metal films / metal oxide films as an electromagnetic shielding film; a transparent radio wave absorber; an ultraviolet absorber; and a transparent semiconductor device.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these Examples.

Example 1
<Manufacture of zinc oxide powder>
Zinc oxide powder (ZnO: manufactured by Kishida Chemical Co., Ltd., purity 99.9%, average particle size of 1 μm or less) was heated from room temperature to 1200 ° C. at a heating rate of 10 ° C./min in the atmosphere, and then 1200 ° C. For 12 hours. The obtained fired product was pulverized and pulverized with a hammer mill to obtain a fired zinc oxide powder. When the tap density was determined for the zinc oxide powder before firing and the fired zinc oxide powder, the zinc oxide powder before firing had a tap density of 1.02 g / cm ³ and the fired zinc oxide powder was 3.92 g / cm ^3. It had a tap density of ³ .
According to JIS K5101, the tap density is filled with zinc oxide powder while applying vibration to a predetermined size graduated cylinder until there is no change in volume of the zinc oxide powder, and the volume (cm ³ ) of the graduated cylinder is obtained. It calculated | required from the filling amount (g) of the zinc oxide powder.

  Moreover, the sintered zinc oxide powder and the unoxidized zinc oxide powder were observed with a scanning electron microscope (SEM). FIG. 1 shows an SEM photograph of the sintered zinc oxide powder, and FIG. 2 shows an SEM photograph of the zinc oxide powder before firing. The zinc oxide powder before firing had an angular shape such as a hexagonal column shape, the particle size was about submicron to 1 μm, and the particle size distribution was narrow. On the other hand, the calcined zinc oxide powder has a substantially spherical shape, and there are fine particles of about submicron to huge particles of several hundred μm, and the particle size distribution is widened to improve the tap density.

<Manufacture of zinc oxide-based sintered body>
Firing zinc oxide powder, titanium carbide powder (TiC: manufactured by Nippon Shin Metal Co., Ltd., purity 99.9%, average particle size 0.9 to 1.5 μm), and aluminum oxide powder (Al ₂ O ₃ : Sumitomo Chemical ( “AKP-3000”, purity 99.9%, average particle size 0.5 μm), the atomic ratio of zinc element, titanium element and aluminum element is Zn: Ti: Al = 98.2: 1. A total of 1600 g was weighed so as to be 0: 0.8 and placed in a polypropylene container. Next, 1800 g of ethanol was added as a mixed solvent, and wet mixed by a wet ball mill mixing method. This wet mixing was carried out for 4 hours using a hard ZrO ₂ ball ( ₂ mmφ) as a ball and using a desktop ball mill. The slurry after wet mixing was taken out, the balls were removed by sieving, and ethanol was removed by an evaporator to obtain a zinc oxide-based powder.

While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. It was 3.86 g / cm ^{3 when} filled and the tap density was determined. Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 69%. The theoretical density was determined by the following formula.
Theoretical density = (Zinc oxide simple substance density x mixing mass ratio) + (Titanium carbide simple substance density x mixing mass ratio) + (Aluminum oxide simple substance density x mixing mass ratio)

After filling the metal container with the zinc oxide powder, the exhaust pipe was welded to the upper lid of the metal container, and then the upper lid and the metal container were welded. In order to confirm the soundness of the welded part of the metal container, a He leak test was performed. The amount of leakage at this time was 1 × 10 ⁻⁹ Pa · m ³ / second or less. Next, the inside of the metal container is depressurized over 7 hours while being heated to 550 ° C., the inside of the metal container is confirmed to be 1.33 × 10 ⁻² Pa or less, the exhaust pipe is closed, and the metal container Was sealed. The sealed metal container was installed in a HIP device (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP treatment. The capsule HIP treatment was performed at 1100 ° C. for 2 hours using argon (Ar) gas (purity 99.9%) at a pressure of 100 MPa as a pressure medium. After the HIP treatment, the metal container was removed to obtain a cylindrical zinc oxide-based sintered body.

When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. The relative density of this zinc oxide-based sintered body was found to be 98.5% by the following formula. The theoretical density is as described above, and the density of the sintered body was determined by the Archimedes method.
Relative density = [(density of sintered body) / (theoretical density)] × 100

The zinc oxide-based sintered body was subjected to grinding and surface polishing, and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn, Ti and Al was Zn: Ti: Al = 98. 2: 1.0: 0.8. The atomic ratio of Zn, Ti, and Al in this zinc oxide-based sintered body is the same as Zn: Ti: Al = 98.2: 1.0: 0.8, which is the atomic ratio at the time of preparation. It can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), zinc oxide (ZnO), zinc titanate (Zn ₂ TiO ₄ ), and zinc aluminate It was a mixture of crystal phases of (ZnAl ₂ O ₄ ), and the crystal phase of titanium carbide and the crystal phase of aluminum oxide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method to obtain a transparent conductive substrate. That is, in the sputtering apparatus (Canon Anelva Engineering Co., Ltd., E-200), the above-mentioned target and a transparent substrate (quartz glass substrate) were respectively installed, and Ar gas (purity 99.9995% or more, Ar pure gas) = 5N) was introduced at 12 sccm, and sputtering was performed under the conditions of a pressure of 0.5 Pa, a power of 75 W, and a substrate temperature of 200 ° C. to form a transparent conductive film having a thickness of 500 nm on the substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 2)
<Manufacture of zinc oxide-based powder>
A total of 1200 g of the zinc oxide powder used in Example 1 and the titanium carbide powder used in Example 1 so that the atomic ratio of zinc element to titanium element is Zn: Ti = 96.5: 3.5. Weigh and dry mix. The obtained mixed powder was heated from room temperature to 1200 ° C. at a heating rate of 10 ° C./min in an inert atmosphere (argon atmosphere), and then fired at 1200 ° C. for 10 hours. The obtained fired product was lightly pulverized by hand in a mortar to obtain a zinc oxide powder. This zinc oxide-based powder had a tap density of 2.94 g / cm ³ . The zinc oxide powder used as a raw material has a tap density of 1.02 g / cm ³ , and the mixed powder (zinc oxide powder and titanium carbide powder) before firing has a tap density of 1.00 g / cm ^3. Had. The tap density was determined by the same method as in Example 1.

<Manufacture of zinc oxide-based sintered body>
While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. When the tap density was determined after filling, it was 2.94 g / cm ³ . Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 53%. The theoretical density was determined by the following formula.
Theoretical density = (Zinc oxide simple substance density x mixing mass ratio) + (Titanium carbide simple substance density x mixing mass ratio)

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The obtained zinc oxide-based sintered body was subjected to grinding and surface polishing and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 96.5: 3. It was 5. This atomic ratio is the same as Zn: Ti = 96.5: 3.5, which is the atomic ratio at the time of preparation, and it can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide-based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), the crystal phase of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) It was a mixture, and the crystal phase of titanium carbide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 3)
<Manufacture of zinc oxide-based powder>
The zinc oxide powder used in Example 1, the titanium carbide powder used in Example 1, and the gallium oxide powder (Ga ₂ O ₃ : manufactured by Sumitomo Chemical Co., Ltd., purity 99.9%, average particle size 1 μm or less) A total of 1200 g was weighed and dry-mixed so that the atomic ratio of zinc element, titanium element and gallium element was Zn: Ti: Ga = 98.2: 1.0: 0.8. The obtained mixed powder was heated from room temperature to 1200 ° C. at a heating rate of 10 ° C./min in an inert atmosphere (argon atmosphere), and then fired at 1200 ° C. for 10 hours. The obtained fired product was lightly pulverized by hand in a mortar to obtain a zinc oxide powder. This zinc oxide-based powder had a tap density of 2.94 g / cm ³ . The zinc oxide powder used as a raw material has a tap density of 1.02 g / cm ³ , and the mixed powder (zinc oxide powder, titanium carbide powder and gallium oxide powder) before firing is 1.00 g / cm ^3. Of tap density. The theoretical density was determined by the following formula.
Theoretical density = (Zinc oxide simple substance density × mixing mass ratio) + (Titanium carbide simple substance density × mixing mass ratio) + (Gallium oxide simple substance density × mixing mass ratio)

<Manufacture of zinc oxide-based sintered body>
While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. When the tap density was determined after filling, it was 2.94 g / cm ³ . Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 53%. The theoretical density was determined in the same manner as in Example 2.

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The obtained zinc oxide-based sintered body was subjected to grinding and surface polishing and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti: Ga = 98.2: 1.0: 0.8. This atomic ratio is the same as Zn: Ti: Ga = 98.2: 1.0: 0.8, which is the atomic ratio at the time of preparation, and it can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide-based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), zinc oxide (ZnO), zinc titanate (Zn ₂ TiO ₄ ), and zinc gallate It was a mixture of crystal phases of (ZnGa ₂ O ₄ ), and the crystal phase of titanium carbide and the crystal phase of gallium oxide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 4)
<Manufacture of zinc oxide-based powder>
The zinc oxide powder used in Example 1 and the titanium carbide powder used in Example 1 were 1200 g in total so that the atomic ratio of zinc element to titanium element was Zn: Ti = 98.5: 1.5. Weigh and dry mix. The obtained mixed powder was heated from room temperature to 1200 ° C. at a heating rate of 10 ° C./min in an inert atmosphere (argon atmosphere), and then fired at 1200 ° C. for 10 hours. The obtained fired product was lightly pulverized by hand in a mortar to obtain a zinc oxide powder. This zinc oxide-based powder had a tap density of 2.94 g / cm ³ . The zinc oxide powder used as a raw material has a tap density of 1.02 g / cm ³ , and the mixed powder (zinc oxide powder and titanium carbide powder) before firing has a tap density of 1.00 g / cm ^3. Had. The tap density was determined by the same method as in Example 1.

<Manufacture of zinc oxide-based sintered body>
While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. When the tap density was determined after filling, it was 2.94 g / cm ³ . Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 53%. The theoretical density was determined in the same manner as in Example 2.

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The obtained zinc oxide-based sintered body was subjected to grinding and surface polishing and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 98.5: 1. It was 5. This atomic ratio is the same as Zn: Ti = 98.5: 1.5, which is the atomic ratio at the time of preparation, and it can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide-based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), the crystal phase of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) It was a mixture, and the crystal phase of titanium carbide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 5)
<Manufacture of zinc oxide-based sintered body>
The calcined zinc oxide powder obtained in Example 1, the titanium carbide powder used in Example 1, and the aluminum oxide powder used in Example 1 have an atomic ratio of zinc element, titanium element, and aluminum element of Zn: A zinc oxide-based powder was obtained by the same procedure as in Example 1 except that Ti: Al = 99.0: 0.7: 0.3.

While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. It was 3.89 g / cm ^{3 when} filled and the tap density was determined. Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 69%. The theoretical density was determined in the same manner as in Example 1.

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The zinc oxide-based sintered body was subjected to grinding and surface polishing, and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn, Ti and Al was Zn: Ti: Al = 99. 0.0: 0.7: 0.3. The atomic ratio of Zn, Ti, and Al in this zinc oxide-based sintered body is the same as Zn: Ti: Al = 99.0: 0.7: 0.3, which is the atomic ratio at the time of preparation. It can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), zinc oxide (ZnO), zinc titanate (Zn ₂ TiO ₄ ), and zinc aluminate It was a mixture of crystal phases of (ZnAl ₂ O ₄ ), and the crystal phase of titanium carbide and the crystal phase of aluminum oxide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 6)
<Manufacture of zinc oxide-based sintered body>
The calcined zinc oxide powder obtained in Example 1 and the titanium carbide powder used in Example 1 were prepared so that the atomic ratio of zinc element to titanium element was Zn: Ti = 95.0: 5.0. A zinc oxide-based powder was obtained in the same procedure as in Example 1 except that it was used.

While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. It was 3.84 g / cm ^{3 when} filled and the tap density was determined. Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 69%. The theoretical density was determined in the same manner as in Example 2.

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The zinc oxide-based sintered body was subjected to grinding and surface polishing, and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti = 95.0: 5. 0.0. In this zinc oxide-based sintered body, the atomic ratio of Zn and Ti is the same as that of Zn: Ti = 95.0: 5.0, which is the atomic ratio at the time of preparation, and zinc is not volatilized. Recognize.
When the crystal structure of the zinc oxide-based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), the crystal phase of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ) It was a mixture, and the crystal phase of titanium carbide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 7)
<Manufacture of zinc oxide-based sintered body>
The calcined zinc oxide powder obtained in Example 1, the titanium carbide powder used in Example 1, and the aluminum oxide powder used in Example 1 have an atomic ratio of zinc element, titanium element, and aluminum element of Zn: A zinc oxide-based powder was obtained in the same procedure as in Example 1 except that Ti: Al = 94.5: 3.5: 2.0 was used.

While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. When the tap density was determined after filling, it was 3.82 g / cm ³ . Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 68%. The theoretical density was determined in the same manner as in Example 1.

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The zinc oxide-based sintered body was subjected to grinding and surface polishing, and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn, Ti and Al was Zn: Ti: Al = 94. .5: 3.5: 2.0. The atomic ratio of Zn, Ti and Al in this zinc oxide-based sintered body is the same as Zn: Ti: Al = 94.5: 3.5: 2.0, which is the atomic ratio at the time of preparation. It can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), zinc oxide (ZnO), zinc titanate (Zn ₂ TiO ₄ ), and zinc aluminate It was a mixture of crystal phases of (ZnAl ₂ O ₄ ), and the crystal phase of titanium carbide and the crystal phase of aluminum oxide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Example 8)
<Manufacture of zinc oxide-based sintered body>
The calcined zinc oxide powder obtained in Example 1, the titanium carbide powder used in Example 1, and the aluminum carbide powder (Al ₄ C ₃ : “ALI03PB” manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9% And an average particle size of 1.0 μm) except that the atomic ratio of zinc element, titanium element and aluminum element was Zn: Ti: Al = 98.5: 1.0: 0.5, A zinc oxide powder was obtained in the same procedure as in Example 1.

While applying vibration to the obtained zinc oxide-based powder in a metal container (outer diameter: 83 mm, inner diameter: 80 mm, height: 78 mm) made of stainless steel (SUS304) until there is no volume change of the zinc oxide-based powder. When the tap density was determined after filling, it was 3.82 g / cm ³ . Since the theoretical density was about 5.6 g / cm ³ , the filling rate was about 68%. The theoretical density was determined by the following formula.
Theoretical density = (Zinc oxide simple substance density x mixing mass ratio) + (Titanium carbide simple substance density x mixing mass ratio) + (Aluminum carbide simple substance density x mixing mass ratio)

  After filling a metal container with zinc oxide-based powder, HIP treatment was performed in the same procedure as in Example 1 to obtain a cylindrical zinc oxide-based sintered body. When this zinc oxide-based sintered body was observed with an electron microscope, it was a dense sintered body having almost no pores. When the relative density of this zinc oxide-based sintered body was determined in the same manner as in Example 1, it was 98.5%.

The zinc oxide-based sintered body was subjected to grinding and surface polishing, and processed into a disk shape having a diameter of 50.8 mm and a thickness of 3 mm. When the obtained workpiece was analyzed with an energy dispersive fluorescent X-ray apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn, Ti and Al was Zn: Ti: Al = 98. .5: 1.0: 0.5. The atomic ratio of Zn, Ti, and Al in this zinc oxide-based sintered body is the same as Zn: Ti: Al = 98.5: 1.0: 0.5, which is the atomic ratio at the time of preparation. It can be seen that zinc is not volatilized.
When the crystal structure of the zinc oxide based sintered body is examined using an X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation), zinc oxide (ZnO), zinc titanate (Zn ₂ TiO ₄ ), and zinc aluminate It was a mixture of crystal phases of (ZnAl ₂ O ₄ ), and the crystal phase of titanium carbide and the crystal phase of aluminum carbide could not be confirmed.

A copper plate was used as a backing plate, and the obtained zinc oxide sintered body was bonded with indium solder to obtain a sputtering target.
Using the obtained sputtering target, a transparent conductive film was formed by a sputtering method in the same procedure as in Example 1 to obtain a transparent conductive substrate. During film formation, abnormal discharge hardly occurred. Specifically, in sputtering for about 1 hour, the number of times the operation of the sputtering apparatus was stopped due to abnormal discharge was within 3 times.

  The atomic ratio of the raw material mixture (the atomic ratio at the time of preparation) is the same as the atomic ratio of the obtained zinc oxide-based sintered body, and an extremely high-density zinc oxide-based sintered body was obtained. Recognize. Therefore, when sputtering was performed using a target obtained by processing a zinc oxide-based sintered body, abnormal discharge hardly occurred and a film could be stably formed.

(Comparative Example 1)
<Manufacture of zinc oxide-based sintered body>
Zinc oxide powder (ZnO: manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide (TiO (II): manufactured by Kojundo Chemical Laboratory Co., Ltd.) having a tap density of 1.02 g / cm ³ were dissolved in zinc. A total of 500 g was weighed so that the atomic ratio of the element, titanium element, and aluminum element was Zn: Ti: Al = 96.5: 3.0: 0.5, and placed in a polypropylene container. Next, 600 g of ethanol was added as a mixed solvent, and wet mixed by a wet ball mill mixing method. This wet mixing was carried out for 4 hours using a hard ZrO ₂ ball ( ₂ mmφ) as a ball and using a desktop ball mill. The slurry after wet mixing was taken out, the balls were removed by sieving, and ethanol was removed by an evaporator to obtain a mixed powder.
When the tap density of the obtained mixed powder was determined in the same procedure as in Example 1, it was 1.01 g / cm ³ .

Using this mixed powder, the HIP process was performed in the same procedure as in Example 1. As a result, the metallic container burst during the HIP process, and the mixed powder was scattered in the HIP processing apparatus, resulting in a zinc oxide-based sintered body. Could not be made.
Since the theoretical density of the obtained mixed powder is about 5.6 g / cm ³ , it can be seen that the filling rate is about 18%. The theoretical density was determined in the same manner as in Example 1. As described above, the filling rate of the zinc oxide-based powder is as low as about 18%, and the shrinkage rate of the metal container is 82%. Therefore, the shrinkage of the metal container cannot follow the shrinkage of the mixed powder. Has burst.

Claims (12)

A titanium carbide powder, obtained by mixing the calcined zinc oxide powder having a 2.8 g / cm ³ or more tap density, a zinc oxide-based powder having a 2.8 g / cm ³ or more tap density,
The titanium carbide powder is contained so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less,
The calcined zinc oxide powder having a tap density of 2.8 g / cm ³ or more is obtained by calcining a raw material zinc oxide powder having a tap density of less than 2.8 g / cm ³ .
A zinc oxide-based powder having a tap density of 2.8 g / cm ³ or more.   At least one selected from the group consisting of gallium oxide powder, aluminum oxide powder and aluminum carbide powder has a ratio of the number of gallium or aluminum atoms of 0.1% to 2.5% with respect to the total number of metal atoms The zinc oxide-based powder according to claim 1, further contained so that A titanium carbide powder, obtained by calcining a mixture of raw material zinc oxide powder having a tap density less than 2.8 g / cm ^3, a zinc oxide-based powder having a 2.8 g / cm ³ or more tap density ,
The titanium carbide powder is contained so that the ratio of the number of titanium atoms to the total number of metal atoms is 0.2% or more and 5% or less.
A zinc oxide-based powder having a tap density of 2.8 g / cm ³ or more.   When the mixture is at least one selected from the group consisting of gallium oxide powder, aluminum oxide powder and aluminum carbide powder, the ratio of the number of atoms of gallium or aluminum to the total number of metal atoms is 0.1% or more 2 The zinc oxide-based powder according to claim 3, further containing so as to be 5% or less.   The zinc oxide-based powder according to claim 1 or 2, wherein the firing is performed at 900 to 1400 ° C in an oxidizing atmosphere.   The zinc oxide-based powder according to any one of claims 1 to 4, wherein the firing is performed at 900 to 1300 ° C in a non-oxidizing atmosphere. The zinc oxide-based powder according to any one of claims 1 to 6, wherein the raw material zinc oxide powder has a tap density of 0.5 to 1.2 g / cm ³ .   A method for producing a zinc oxide-based sintered body, comprising a step of filling a metal container with the zinc oxide-based powder according to any one of claims 1 to 7 and subjecting the capsule to hot isostatic pressing.   The manufacturing method according to claim 8, wherein a sintering temperature in the capsule hot isostatic pressing is 900 to 1400 ° C., and a relative density of the sintered body is 98% or more.   The manufacturing method according to claim 8 or 9, wherein the capsule hot isostatic pressing is performed in an inert gas atmosphere.   The manufacturing method according to any one of claims 8 to 10, wherein the capsule hot isostatic pressing is performed under a pressure condition of 50 MPa or more. A target used for film formation by sputtering, ion plating, pulsed laser deposition (PLD) or electron beam (EB) vapor deposition,
The target obtained by processing the zinc oxide-type sintered compact obtained by the manufacturing method in any one of Claims 8-11.