JPH08277117A - Transparent and electroconductive oxide material - Google Patents

Abstract

PURPOSE: To obtain a double oxide material which has high visible-light transmission and good electroconductivity and is useful as a transparent electrode, an antistatic membrane or an electromagnetic shielding membrane. CONSTITUTION: This double oxide has a crystalline structure of triple rutile type, comprises zinc oxide or magnesium oxide and antimony oxide at a molar ratio of (1+x)/2, where -0.1<=X<=0.1, and contains at least one of metallic element selected from among In, Ga, Al, Y and La.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transparent electrode for solar cells, liquid crystal devices (LCDs), antistatic films, electromagnetic shielding films, anti-fog glass, heat ray-reflecting glass, etc. The present invention relates to a transparent conductive oxide material which has a good electric conductivity while having a good electric conductivity.

[0002]

2. Description of the Related Art Currently, transparent conductive materials are used for transparent electrodes of LCDs and solar cells, electromagnetic shielding films, antistatic films, anti-fog glass, heat-reflecting glass and the like. Tin-based materials are widely used for the above applications because of their relatively high electrical conductivity and their ability to transmit visible light.

In applying the above-mentioned materials, these materials are formed by a physical film forming method such as a sputtering method or an ion plating method, or a chemical film forming method such as a sol-gel method or a spray pyrolysis method. Has been used.

Here, in the case of transparent electrodes for LCDs and solar cells, the market of which has been greatly expanding in recent years, since the electric conductivity and the patterning property are relatively good, a few mol of tin is added to indium oxide. % Added, ITO (Indi
um-Tin-Oxide) is mainly used.

However, while ITO is superior in conductivity to other conventional materials, it is not transparent.
Visible light transmission is not high due to the intrinsic characteristics of the material,
In particular, there is a large amount of absorption of visible light in the short wavelength region, and the thin film after film formation has the drawback of appearing slightly bluish.

Further, indium oxide, which is a main constituent of ITO, has a poor resource property and is quite expensive at present, so that the film forming cost is also a problem. In addition, since indium oxide is difficult to sinter, it is not easy to manufacture a high-density target by a sputtering method which is a typical film forming method.

[0007]

In order to solve the above problems, the present inventor has made earnest studies and, as a result, has made it possible to obtain a visible light transmissivity and an electric conductivity by using a double oxide having a specific composition. The inventors have found that and reached the present invention.

That is, the present invention is a complex oxide having a triple rutile type crystal structure, and the molar ratio of zinc oxide or magnesium oxide to antimony oxide in the complex oxide is (1 + X): 2 (however, , -0.1≤X≤0.1)
And In, Ga, Al, La, Y in the mixed oxide
The present invention provides a transparent conductive oxide material containing at least one metal element selected from the group consisting of:

In the present invention, in the above composition, the molar ratio of zinc oxide or magnesium oxide to antimony oxide is (1 + X): 2 (provided that -0.1≤X≤0.
It is important that it is 1).

The complex oxide having a triple rutile type crystal structure of the above constituent elements has a wider bandgap than ITO, and its basic absorption edge is near the ultraviolet. Therefore, I
Compared with TO, absorption of visible light in the short wavelength region is small, and excellent visible light transmittance can be expected. In addition, the triple rutile type crystal structure is very similar to the rutile type crystal structure showing high conductivity. Since it has a unit cell, high conductivity can be expected. However, if the proportion of the composition is out of the above range, a second phase other than the triple rutile phase showing high electric conductivity is generated after firing, and the electric conductivity is lowered, which is not preferable.

Next, in order to obtain the double oxide of the present invention having a high density and a uniform composition with a relative density of 80% or more,
After using a raw material oxide having an average particle size of 1 μm or less and a purity of 99.99% or more and mixing by a ball mill or the like and molding, 500 to 1
It is calcined at 200 ° C. and further sintered in the atmosphere in the temperature range of 1200 to 1600 ° C. Mixing is preferably performed by a wet ball mill, and if the temperature is out of the sintering temperature range, the triple rutile phase is not sufficiently formed, or the second phase other than the triple rutile phase is formed, which is not preferable.

Further, by adding a high-valent metal element to the above composition and performing substitution solid solution, carrier injection caused by non-stoichiometry is also possible. In this case, the high valence metal element is preferably a trivalent metal element having a higher valence than Zn ²⁺ and Mg ²⁺ , In, Ga, Al, La and Y, and is selected from these. By adding at least one kind of metal element, carrier injection is possible and a material having improved electric conductivity can be obtained.

In this case, the amount of the metallic element added is not particularly limited, but 0.01 to 20 atomic% of at least one metallic element selected from In, Ga, Al, La, Y metals or their oxides is used. It is desirable to include. If it exceeds this range, the metal element exceeds the solid solubility limit, which may cause the formation of a second phase other than the spinel phase, resulting in a decrease in electrical conductivity. Therefore, it is desirable to add the metal element within the above range.

On the other hand, the main constituent elements of the complex oxide of the present invention are Sb and Zn or Mg, which are rich in natural resources as compared with In, which is the main constituent element of ITO, and are very inexpensive. Moreover, the sinterability is good. For this reason,
There is an advantage that a sputtering target, which is a film forming material, can be manufactured at low cost.

[0015]

EXAMPLES The present invention will be further described below based on examples, but the present invention is not limited to these examples.

Example 1 A zinc oxide powder and an antimony oxide powder having an average particle size of 1 μm or less and a purity of 99.99% were weighed out in a molar ratio of 1: 2 and mixed in a wet ball mill in an ethanol solvent.
Furthermore, after drying the obtained slurry at 60 ° C. for 24 hours,
It was calcined in an alumina crucible at 1000 ° C. for 5 hours. The precursor after calcination is wet-ball milled again in ethanol solvent, dried, and then 2% by weight of PVA as a molding binder.
Was added.

Then, the particles are sized to 150 μm under,
After uniaxial molding with a size of 15 mm × 3 mmt and rubber pressing (2 t / cm ² ), the molded green disk was baked at 1400 ° C. for 5 hours in the air. As a result of analysis by the powder X-ray diffraction method, only the triple rutile phase was found in the sintered body prepared as described above, and the second phase other than the triple rutile phase was not found.

Example 2 Magnesium oxide powder and antimony oxide powder having an average particle size of 1 μm or less and a purity of 99.99% were weighed in a molar ratio of 1: 2 and mixed in an ethanol solvent by a wet ball mill. Further, the obtained slurry was dried at 60 ° C. for 24 hours and then calcined in an alumina crucible at 1000 ° C. for 5 hours. The precursor after calcination was wet-ball milled again in an ethanol solvent, dried, and then 2% by weight of PVA was added as a molding binder.

Then, the particles are sized to 150 μm under, and φ
After uniaxial molding with a size of 15 mm × 3 mmt and rubber pressing (2 t / cm ² ), the molded green disk was baked at 1400 ° C. for 5 hours in the air. As a result of analysis by the powder X-ray diffraction method, only the triple rutile phase was found in the sintered body prepared as described above, and the second phase other than the triple rutile phase was not found.

Example 3 Zinc oxide powder, antimony oxide powder and indium oxide powder having an average particle size of 1 μm or less and a purity of 99.99% were weighed so that the molar ratio was 0.9: 2: 0.1, Wet ball mill mixing in ethanol solvent. Further, the obtained slurry was dried at 60 ° C. for 24 hours and then calcined in an alumina crucible at 1000 ° C. for 5 hours. The precursor after calcination was wet-ball milled again in an ethanol solvent, dried, and then 2% by weight of PVA was added as a molding binder.

Then, the particles are sized to 150 μm under,
After uniaxial molding with a size of 15 mm × 3 mmt and rubber pressing (2 t / cm ² ), the molded green disk was baked at 1400 ° C. for 5 hours in the air. As a result of analysis by the powder X-ray diffraction method, only the triple rutile phase was found in the sintered body prepared as described above, and the second phase other than the triple rutile phase was not found.

Example 4 Zinc oxide powder, antimony oxide powder and aluminum oxide powder having an average particle size of 1 μm or less and a purity of 99.99% were weighed so that the molar ratio was 0.9: 2: 0.1, Wet ball mill mixing in ethanol solvent. Further, the obtained slurry was dried at 60 ° C. for 24 hours and then calcined in an alumina crucible at 1000 ° C. for 5 hours. The precursor after calcination was wet-ball milled again in an ethanol solvent, dried, and then 2% by weight of PVA was added as a molding binder.
After that, size is adjusted to 150 μm under, φ15 mm × 3
mmt size uniaxial molding and rubber press (2t /
cm ² ), and the green disc after molding is 1400
Firing was performed in the air at 5 ° C for 5 hours. As a result of an analysis by a powder X-ray diffraction method, only the triple rutile phase was found in the sintered body prepared as described above, and the second phase other than the triple rutile phase was not found.

Comparative Example 1 Indium oxide powder and tin oxide powder having an average particle diameter of 1 μm or less and a purity of 99.99% were weighed so that the molar ratio was 0.9: 0.1, and wet ball mill in an ethanol solvent. Mixed. Further, the obtained slurry was dried at 60 ° C. for 24 hours and then calcined in an alumina crucible at 1000 ° C. for 5 hours. The precursor after calcination was wet-ball milled again in an ethanol solvent, dried, and then 2% by weight of PVA was added as a molding binder.

After that, the particle size is adjusted to 150 μm under, and φ
After uniaxial molding with a size of 15 mm × 3 mmt and rubber pressing (2 t / cm ² ), the molded green disk was baked at 1400 ° C. for 5 hours in the air. As a result of analysis by the powder X-ray diffraction method, only the indium oxide phase was found in the sintered body prepared as described above, and the second phase other than the indium oxide phase was not found.

[Evaluation of Physical Properties] As a method for evaluating visible light transmittance in the present invention, since the sample is a polycrystalline ceramic, a diffuse reflectance measuring method which is equivalent to the transmittance measuring was adopted. Here, as the measurement sample, the sinter prepared in the above example was pulverized and uniaxially molded into a size of φ25 mm × 3 mmt.

The standard white sample has a purity of 99.99.
% MgO powder molded by the same method as above was used. On the other hand, for the electrical conductivity measurement, a normal DC four-terminal method was employed, in which the sintered body prepared in the above example was cut into a rectangular parallelepiped with a diamond cutter and an element equipped with voltage and current electrodes was used.

Table 1 shows the results of measuring the diffuse reflectance of the composite oxides prepared in Examples and Comparative Examples of the present invention. As is clear from Table 1, the composite oxide of the present invention has a reflectance as a whole as compared with the conventional material ITO (Comparative Example 1),
That is, it can be seen that the visible light transmittance is extremely high, and the absorption particularly on the short wavelength side of the visible region is significantly small.

[0028]

[Table 1]

Table 2 shows the electric conductivity of the composite oxides prepared in the examples of the present invention at -40 ° C, room temperature (25 ° C) and 100 ° C. Here, it can be seen that each oxide exhibits good electrical conductivity, which is close to the metallic conductive behavior that the electrical conductivity hardly depends on temperature.

[0030]

[Table 2]

[0031]

INDUSTRIAL APPLICABILITY The complex oxide having a triple rutile type crystal structure of the present invention shows excellent electric conductivity, but is significantly improved in transparency as compared with conventional materials, particularly in the visible wavelength short wavelength side. , And material cost reduction.

Claims (3)

[Claims] 1. A composite oxide having a triple rutile type crystal structure, wherein the molar ratio of zinc oxide and antimony oxide in the composite oxide is (1 + X): 2 (where -0.1 ≦ X
≦ 0.1) A transparent conductive oxide material. 2. A complex oxide having a triple rutile type crystal structure, wherein the molar ratio of magnesium oxide to antimony oxide in the complex oxide is (1 + X): 2 (provided that −
0.1 ≦ X ≦ 0.1) A transparent conductive oxide material. 3. In, Ga, Al, L in the double oxide
3. The transparent conductive oxide material according to claim 1, which contains at least one metal element selected from a and Y.