JPH06239615A - Production of copper oxide-based electrically conductive ceramic thin film - Google Patents

Abstract

PURPOSE:To provide a method for producing a copper oxide-based electrically conductive ceramic thin film in which the synthesis and formation of the thin film have hitherto been difficult by using a readily available raw material at a low cost. CONSTITUTION:An aqueous solution of a mixture composed of copper nitrate, copper chloride, indium nitrate and lead nitrate is sprayed on a substrate heated at 300-550 deg.C to deposit droplets thereof. Thereby, the objective copper oxide- based electrically conductive ceramic thin film expressed by the formula Cu6(InxPby)O8-zCl [(x+y) is 1; 0<=(x)<1; 0<(y)<=1; 0<=(z)<=1] is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper oxide-based conductive ceramic thin film, and more particularly to a method for producing a copper oxide-based conductive ceramic thin film using raw materials that are easily and inexpensively available.

[0002]

2. Description of the Related Art Conductive ceramics are peculiar to ceramics
Because of its excellent properties such as corrosion resistance and heat resistance,
It is used in a wide range of fields such as poles and heating elements. For example
RuO ₂Is the electrode material and the thermal head of the thermal transfer printer.
It is used as a service. Furthermore, conductive ceramic thin film
Another example of application is to use transparent electrodes of ITO ceramics.
Application of PLZT ceramics to optical switches
The fields of application are expanding.

By the way, the compound represented by the composition formula Cu ₆ O ₈ PbCl is known as a naturally occurring mineral crystal under the name of Murdkite, and various applications are expected as one of electrically conductive ceramic materials. Has been done. Further, by substituting In for a part of Pb in the above composition formula, it is possible to obtain a ceramic material having better conductivity.

[0004] It is noted that a production method of merkudite is known by a hydrothermal reaction from a mixed aqueous solution of copper chloride and lead hydroxide, but the reproducibility of the reaction is poor and Pb ₂
It was difficult to synthesize a large amount because it was only produced as a by-product of CuCl ₂ (OH) ₄ .

On the other hand, it has been extremely difficult to make the above-mentioned mardkites and In-substituted mardkites into thin films and apply them to electrode materials and the like.

[0006]

As described above, since conductive ceramics are used in a wide range of fields and importance is attached to their usefulness, a method for inexpensively and easily manufacturing a conductive ceramic thin film is always desired. It is rare. Therefore, the object of the present invention is to provide a method for producing a copper oxide-based conductive ceramic thin film, which has been difficult to synthesize and thin in the related art, by using raw materials that are easily and inexpensively available. To do.

[0007]

The present invention is based on the general formula Cu
_{6 (In x Pb y) O} 8-z Cl [where, x + y = 1,0
A method for producing a copper oxide-based conductive ceramic thin film represented by ≦ x <1,0 <y ≦ 1,0 ≦ z ≦ 1], which comprises copper nitrate, copper chloride, indium nitrate, and lead nitrate. It is a method for producing a copper oxide-based conductive ceramics thin film, which comprises atomizing an aqueous solution of a mixture onto a substrate heated to 300 ° C. to 550 ° C. and depositing droplets thereof.

The present invention will be described in detail below. First, copper nitrate, copper chloride, indium nitrate and lead nitrate were mixed at a molar ratio of 5: 1 :.
(X + y), where (x + y) = 1, that is, the molar ratio of the contained metals in the mixture is Cu: (In + Pb) = 6: 1, and weighed and mixed to obtain an aqueous solution having an appropriate concentration.

At this time, if the molar ratio of Cu exceeds 6 with respect to the sum of In and Pb, CuO or Cu ₂ (NO ₂ ) is contained in the conductive ceramic obtained after heating described later.
It is not preferable because impurities such as (OH) ₃ resulting from excess copper are mixed. On the contrary, when the Cu molar ratio is less than 6 with respect to the sum of In and Pb, In
Impurities resulting from excessive In and Pb such as ₂ O ₃ and PbO are mixed, which is not preferable.

The mixing ratio of copper nitrate and copper chloride is also mentioned.
For example, if the molar ratio of copper nitrate exceeds 5 with respect to copper chloride,
A part of the Cl element in the general formula [I] shown in₃)
Group-substituted thermally labile compound, Cu₆(In_x
Pb_y) O_8-zCl_1-m(NO₃)_mIs good for
Not good. On the contrary, the molar ratio of copper nitrate to copper chloride is 5
If it is smaller, the production rate of conductive ceramics decreases,
Insulating material Cu ₂OCl₂Is generated,
Not preferable.

As for the mixing ratio of In and Pb, as described above, it is sufficient that the total number of moles of both is 1/6 of copper, and there is no particular limitation.

Next, the obtained mixture aqueous solution is atomized by using an ultrasonic atomizer or the like, and its droplets are preliminarily 300-550.
Conductive ceramics are obtained by depositing on a substrate heated to ℃. Here, if the heating temperature exceeds 550 ° C., CuO and In ₂ O ₃ which are insulating ceramics are decomposed and generated, the generation ratio of the conductive ceramics is reduced, and when the temperature is higher, all become insulating ceramics, which is not preferable. . On the other hand, if the heating temperature is less than 300 ° C, the decomposition reaction of nitrate does not proceed efficiently.

The heating time is appropriately selected from the range of 30 minutes to 15 hours, and the heating can be carried out by using an ordinary heating device such as an electric furnace.

As a method of mixing the raw material compounds of copper nitrate, copper chloride, indium nitrate, and lead nitrate, a method of pulverizing and mixing each raw material compound with a ball mill or the like is generally used, but a method for obtaining a uniform aqueous solution is obtained. If so, the method is not particularly limited.

Further, the method of atomizing the mixed aqueous solution is not limited to the ultrasonic atomizer, and other means such as a spray method can be adopted.

The material of the substrate is not particularly limited, but sapphire, magnesium oxide, strontium titanate, etc. can be used.

[0017]

The X-ray diffraction spectrum of the conductive ceramics obtained by the manufacturing method of the present invention is recognized to be a cubic system belonging to the space group Fm3m, which is similar to Murdocite. In this crystal, cubic oxygen partially deficient is also included, and the oxidation number of copper is considered to have a mixed valence of +2 to +3, which is presumed to contribute to conductivity.

As described above, according to the present invention, the copper oxide type conductive ceramics thin film can be easily manufactured using inexpensive and easily available raw materials such as nitrates and chlorides.

Incidentally, some of the lead atoms in the copper oxide type conductive ceramics can be replaced with In at an arbitrary ratio.

At this time, according to the present invention, since the mixed aqueous solution of the metal salt is used as the raw material, the composition control is extremely easy,
By doing so, it is possible to easily obtain a ceramic thin film having a lower specific resistance value and excellent conductivity.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Example 1 Copper nitrate trihydrate 7.824
g, 1.104 g of cupric chloride dihydrate, and 1.073 g of lead nitrate were thoroughly mixed, and water was added to obtain a 1 mol / l aqueous solution. This aqueous solution was made into a mist by an ultrasonic atomizer and introduced into an electric furnace heated to 350 ° C. to deposit droplets on a magnesium oxide substrate placed in the furnace.

As a result of performing such processing for 5 hours, FIG.
A copper oxide-based conductive ceramic having a cubic X-ray diffraction spectrum (used tube: CuKα) as shown in (3) was obtained. From this X-ray diffraction spectrum, it was confirmed that Cu ₆ PbO ₈ Cl was produced in this example. The specific resistance of the conductive ceramics thus obtained was 1 Ω · cm at room temperature.

Example 2 A mixture consisting of 7.4 g of copper nitrate trihydrate, 1.044 g of cupric chloride dihydrate, 1.149 g of indium nitrate trihydrate and 0.406 g of lead nitrate. Was mixed well and water was added to make a 1 mol / l aqueous solution. This aqueous solution is made into a mist by an ultrasonic atomizer, and 5
Droplets were deposited on a magnesium oxide substrate placed in an electric furnace heated to 20 ° C. and placed in the furnace.

As a result of performing such processing for 20 minutes, as shown in FIG.
A copper oxide-based conductive ceramic having a cubic X-ray diffraction spectrum as shown in (3) was obtained. From this X-ray diffraction spectrum, Cu ₆ (In _0.4 Pb)
It was confirmed that _0.6 ) O ₈ Cl was produced. The specific resistance of the conductive ceramics thus obtained was 10 mmΩ · cm at room temperature.

[0026]

As described above in detail, according to the method for producing a copper oxide type conductive ceramics thin film of the present invention, it is difficult to prepare the copper oxide type conductive ceramics thin film, which is excellent in crystallinity and uniformity. The thin film can be easily manufactured.

The copper oxide type conductive ceramics can be suitably applied as various electrodes and raw materials for heating elements. Therefore, the significance of the present invention to provide a thin film of such a material inexpensively and easily is extremely deep.

[0028]

[Brief description of drawings]

FIG. 1 is a graph showing an X-ray diffraction spectrum of a copper oxide-based conductive ceramic obtained in Example 1.

2 is a graph showing an X-ray diffraction spectrum of the copper oxide-based conductive ceramic obtained in Example 2. FIG.

Claims (1)

[Claims] 1. A general _{formula, Cu 6 (In x Pb y} ) O 8-z C
l [however, x + y = 1,0 ≦ x <1,0 <y ≦ 1,0 ≦
z ≦ 1], the method for producing a copper oxide-based conductive ceramics thin film, wherein a mixed aqueous solution of copper nitrate, copper chloride, indium nitrate, and lead nitrate is added at 300 ° C.
A method for producing a copper oxide-based conductive ceramic thin film, which comprises atomizing onto a substrate heated to 550 ° C. and depositing the droplets.