JP5403500B2 - Conductive material - Google Patents

Description

  The present invention relates to a conductive material having visible light permeability.

This kind of transparent conductive material is an important material used for display panels, solar cells and the like. The transparent conductor currently mainly used is tin-added indium oxide (ITO). However, since indium is a rare element, development of a transparent conductor that does not contain this is required.
One of the typical candidates for the ITO substitute material is the zinc oxide-based material shown in Patent Documents 1 to 3, but in any document, the material used as a material is a part of the zinc atom in the zinc oxide to other atoms. The crystal structure is a zinc oxide structure (wurtzite structure).
These performances still do not reach ITO, and it is unlikely that dramatic improvements will be made in the future. Therefore, a material that is a candidate for a new ITO alternative material having a crystal structure different from that of zinc oxide is demanded.
US Pat. No. 3,580,022 JP-A 61-205619 JP 2005-306684 A Journal of Solid State Chemistry, 116, 170-178 (1995)

  In view of such circumstances, an object of the present invention is to provide a conductive material that does not use indium.

Invention 1 is a conductive material having visible light permeability, and is represented by a chemical formula Ga _2−x M _x O ₃ (ZnO) _m (m is a natural number, M: an element that can be substituted for Ga). It has the crystal structure shown in 1.

Non-Patent Document 1 reports the existence of a series of compound groups represented by a composition formula of Ga ₂ O ₃ (ZnO) _m (m is a natural number).
The present invention finds out that the material having such a composition has the crystal structure shown in FIG. 1 and has high conductivity, and utilizes this.

An element that can replace Ga is an element that becomes trivalent ions in an oxide like Ga and has an ion size that is not extremely different from that of gallium. For example, Al and In correspond to this.
It can be easily analogized that even if a part of gallium in Examples 1 to 4 is replaced with Al, In, or an element similar to these, basically the same effect can be exhibited.
When the composition parameter m in Examples 1 to 4 is replaced with any rational number or irrational number greater than or equal to 0, two coexistence states corresponding to the two integers m1 and m2 (where m1 <m <m2) are the closest to it. It becomes. From this, it can be easily inferred that the same operational effects as when m is an integer can be exhibited.
Since the mixed gas of Example 2 replaces the reducing gas with CO and the inert gas with N _2, He, Ne, or Xe, the effect of introducing oxygen defects into the sample is essentially the same, so the same effect is obtained. It can be easily analogized that the effect can be exhibited.
In addition, even if the ratio of the mixed gas is replaced with an arbitrary ratio, or even if only the reducing gas is used, the effect of introducing oxygen defects into the sample is essentially the same, so it is easy to achieve the same effect. Can be analogized.
In the following examples, the temperature is shown in units of 50 ° C.

Zinc oxide (purity 99.99%) 3.662 g and gallium oxide (purity 99.99%) 0.937 g were weighed and ground and mixed with an agate mortar while adding a small amount of ethanol.
The mixing ratio of the oxide at this time corresponds to m = 9 in the general formula Ga ₂ O ₃ (ZnO) _m .
A platinum tube (outer diameter 6 mm, length 50 mm) was filled with a part (0.93 g) of the above mixture.
(At this time, after crushing both ends of the platinum tube, it was folded and further crushed.)
This was held in an electric furnace at 1450 ° C. for 4 days, and then rapidly cooled by taking it out of the furnace.
The product was pulverized using an agate mortar, filled in a platinum tube in the same manner as described above, held at 1450 ° C. for 3 days, taken out of the furnace, and rapidly cooled.
A part of the product was pulverized and identified by X-ray diffraction measurement.
It was confirmed that this was a phase corresponding to m = 9 in a series of long-period structure compound groups represented by Ga ₂ O ₃ (ZnO) _m .
A 1.2 mm × 1.7 mm × 3.6 mm prism was cut from the product, and a GaIn alloy was applied to both end faces to form an electrode.
The electrical resistance was measured by the direct current four-terminal method, and the conductivity was determined by correcting the sample shape. The result is shown in FIG.
As an oxide sintered body, it exhibits very high electrical conductivity.
A small amount of oxygen vacancies are present in the crystal structure, which is considered to cause the generation of electrons as carriers.

Zinc oxide (purity 99.99%) 3.662 g and gallium oxide (purity 99.99%) 0.937 g were weighed and ground and mixed with an agate mortar while adding a small amount of ethanol.
The mixing ratio of the oxide at this time corresponds to m = 9 in the general formula Ga ₂ O ₃ (ZnO) _m .
A platinum tube (outer diameter 6 mm, length 50 mm) was filled with a part (0.93 g) of the above mixture.
(At this time, after crushing both ends of the platinum tube, it was folded and further crushed.)
This was held in an electric furnace at 1450 ° C. for 4 days, and then rapidly cooled by taking it out of the furnace.
The product was pulverized using an agate mortar, filled in a platinum tube in the same manner as described above, held at 1450 ° C. for 3 days, taken out of the furnace, and rapidly cooled.
When a part of the product was pulverized and this substance was identified by X-ray diffraction measurement, it corresponds to m = 9 in a series of long-period structure compounds represented by Ga ₂ O ₃ (ZnO) _m. Phase was confirmed.
A 1.1 mm × 1.8 mm × 3.3 mm prism is cut out from the sample and kept in a mixed gas of hydrogen 6 cc / min and argon 194 cc / min, and the temperature is raised from room temperature to 500 ° C. at a rate of 300 ° C./h. did.
After maintaining for 1 hour, the sample was left in the furnace and allowed to cool to room temperature with the output of the electric furnace being 0.
A GaIn alloy was applied to both end faces of the sample taken out to form an electrode, and after measuring the electrical resistance, the conductivity was determined by correcting the sample shape. The result is shown in FIG.
This treatment improved the electrical conductivity, which is probably because oxygen defects were further introduced.

Zinc oxide (purity 99.99%) 3.662 g and gallium oxide (purity 99.99%) 0.937 g were weighed and ground and mixed with an agate mortar while adding a small amount of ethanol.
The mixing ratio of the oxide at this time corresponds to m = 9 in the general formula Ga ₂ O ₃ (ZnO) _m .
A platinum tube (outer diameter 6 mm, length 50 mm) was filled with a part (0.93 g) of the above mixture.
(At this time, after crushing both ends of the platinum tube, it was folded and further crushed.)
This was held in an electric furnace at 1450 ° C. for 4 days, and then rapidly cooled by taking it out of the furnace.
The product was pulverized using an agate mortar, filled in a platinum tube in the same manner as described above, held at 1450 ° C. for 3 days, taken out of the furnace, and rapidly cooled.
A part of the product was pulverized and identified by X-ray diffraction measurement.
It was confirmed that this was a phase corresponding to m = 9 in a series of long-period structure compound groups represented by Ga ₂ O ₃ (ZnO) _m .
A 1.2 mm × 1.6 mm × 3.5 mm prism was cut out from this sample, held in an electric furnace at 1000 ° C. for 10 minutes in an electric furnace using a platinum crucible, and then taken out of the furnace and rapidly cooled.
A GaIn alloy was applied to both end faces of the sample taken out to form an electrode, and after measuring the electrical resistance, the conductivity was determined by correcting the sample shape. The result is shown in FIG.
This treatment significantly reduced the electrical conductivity. This is presumably because oxygen defects in the crystal structure disappeared.

Zinc oxide (purity 99.99%) 3.051 g and gallium oxide (purity 99.99%) 0.469 g were weighed and ground and mixed with an agate mortar while adding a small amount of ethanol.
The mixing ratio of the oxide at this time corresponds to m = 15 in the general formula Ga ₂ O ₃ (ZnO) _m .
A platinum tube (outer diameter 6 mm, length 50 mm) was filled with a part of the above mixture (2.367 g).
(At this time, after crushing both ends of the platinum tube, it was folded and further crushed.)
This was held in an electric furnace at 1450 ° C. for 4 days, and then rapidly cooled by taking it out of the furnace.
The product was pulverized using an agate mortar, filled in a platinum tube in the same manner as described above, held at 1450 ° C. for 3 days, taken out of the furnace, and rapidly cooled.
A part of the product was pulverized and identified by X-ray diffraction measurement.
The generation of a phase corresponding to m = 15 in a series of long-period structure compounds represented by Ga ₂ O ₃ (ZnO) _m was observed, but the diffraction peak was wide and the periodicity of the crystal structure was incomplete. It turned out to be.
A 2.8 mm × 3.0 mm × 9.7 mm prism was cut out from the product, and a GaIn alloy was applied to both end faces to form an electrode.
The electrical resistance of this was measured, and the conductivity was determined by correcting the sample shape. The result is shown in FIG.
As an oxide sintered body, it exhibits very high electrical conductivity.
A small amount of oxygen vacancies are present in the crystal structure, which is considered to cause the generation of electrons as carriers.

  The conductive oxide of the present invention can be applied to a transparent conductive material, a thermoelectric conversion material, a gas sensor, a light emitting material, a catalyst material, and the like.

The figure which shows the crystal structure of this invention Flow showing manufacturing method and electrical conductivity of product manufactured by each method

Claims (1)

A conductive material having visible light permeability, represented by the chemical formula Ga ₂ O ₃ (ZnO) _m (m is a natural number), having an orthorhombic crystal structure, and having an oxygen defect in the crystal structure .