JP2015101493A - Conductive zinc oxide powder and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy method for producing a conductive zinc oxide powder in which aluminum is solid-solved and which has a low volume resistivity and is reduced deterioration thereof with time, and to provide a new conductive zinc oxide powder obtained by the production method in which aluminum is solid solved.SOLUTION: There is provided: a method for producing a conductive zinc oxide powder by mixing a zinc oxide powder and an Al-N-H-based alloy having an imide group and/or an amide group, followed by firing at a temperature range of 900 to 1200°C in an inert atmosphere; and a conductive zinc oxide powder in which aluminum and nitrogen are solid-solved.

Description

  The present invention relates to a simple method for producing a conductive zinc oxide powder, and to a conductive zinc oxide powder obtained by the simple production method and having a low volume resistivity and little deterioration of the volume resistivity with time.

  Currently, indium oxide in which antimony is dissolved is used for most of the transparent electrode films used in solar cells and the like. However, considering the cost problems caused by the use of rare metal indium and the effects on the human body due to the use of antimony, from the viewpoint of cost and safety, materials for transparent electrode films that replace indium oxide in which antimony is dissolved Has been explored.

  From such a background, zinc oxide in which aluminum is dissolved is now attracting attention as a material for the transparent electrode film. Zinc oxide has low risk to the human body, is inexpensive, has a favorable band gap as a transparent electrode film, and aluminum has an ionic radius close to that of zinc. Because it is cheap.

  The transparent electrode film is generally formed by film formation by a sputtering method using a sintered body target. In order to obtain a transparent electrode film with good conductivity, a sintered body target with good conductivity is required, and for this purpose, powder with good conductivity is required. Therefore, researches for improving various properties such as conductivity of conductive zinc oxide powder in which aluminum is dissolved are actively conducted in recent years.

  Conductive zinc oxide powder in which aluminum is dissolved is usually obtained by neutralizing a mixed solution of a water-soluble zinc compound and a water-soluble compound of a solid solvent with an aqueous solution such as alkali hydroxide or alkali carbonate to obtain a coprecipitate precipitate. Then, the obtained coprecipitate precipitate is washed, dried, and then heated and fired in a reducing atmosphere.

  For example, Patent Document 1 describes a method for producing a conductive zinc oxide powder in which aluminum is dissolved as follows. First, a zinc oxide powder and an ammonium bicarbonate powder acting as a disintegrant are reacted in an aqueous solution to produce basic zinc carbonate, and the resulting basic zinc carbonate is aged to grow crystals. Next, an aqueous dispersion of basic zinc carbonate that has been crystal-grown and an aqueous aluminum sulfate solution are mixed and aged, and the resulting solid matter is collected by filtration. Then, after the obtained solid is dried and calcined, it is further reduced and fired in a hydrogen atmosphere, and the obtained fired product is crushed to produce a conductive zinc oxide powder.

  Patent Document 2 describes the following method for producing a conductive zinc oxide powder in which aluminum is dissolved. First, an aqueous solution of zinc sulfate and aluminum sulfate is gradually dropped and reacted with an aqueous solution of sodium carbonate that acts as a disintegrant to form a precipitate. Next, after the produced precipitate is washed, the precipitate is separated by solid-liquid separation and dried. Then, after the dried precipitate is pulverized, it is fired in a reducing atmosphere containing hydrogen gas and water vapor, and the resulting aggregate is pulverized to produce a conductive zinc oxide powder.

  Patent Document 3 describes a method for producing a conductive zinc oxide powder in which aluminum is dissolved as follows, using aluminum sulfate, aluminum nitrate or aluminum chloride as an activator (aluminum source). . First, an aqueous solution in which any one of these aluminum sources is dissolved is mixed with an aqueous solution in which ammonium bicarbonate, ammonium carbonate, urea, or ammonium nitrate acting as a disintegrant is dissolved. The obtained mixed liquid is put into an aqueous dispersion of zinc oxide, and after raising the temperature, Aerosil is added and stirred. This is a method for producing a conductive zinc oxide powder by filtering, washing with water after completion of stirring, drying and then heat-treating in a reducing atmosphere.

Japanese Patent No. 4393460 JP 2012-62219 A JP-A-1-126228 Japanese Patent No. 2707325

Lithium aluminum amide, LiAl (NH2) 4-preparationn, x-ray study, IR spectrum, and thermal decomposition Zeitschrift fuer Anorganische und Allgemeine Chemie (1985), 531, 125-39. Optical investigations on the annealing behavior of gallium‐ and nitrogen-implanted ZnO, JOUNAL of APPLIED PHYSICS, VOLUME 95, NUMBER 7

  As described above, the production of a conductive zinc oxide powder in which aluminum is dissolved is usually a step of preparing a solution of a zinc salt and an aluminum salt, a step of disintegrating zinc crystals using a disintegrant, and zinc and aluminum. The process which produces | generates the deposit containing, the process of wash | cleaning the obtained precipitate, the process of drying the precipitate after washing | cleaning, and the process of baking the precipitate after drying are required. That a disintegrating agent is required to facilitate dissolution of aluminum in zinc, that the conventional aluminum source has low reactivity with zinc oxide, and that an auxiliary agent is required to accelerate the reaction, In order to mix the zinc source uniformly, mixing in an aqueous solution is essential, and subsequent steps such as washing and drying are required, and reducing gas must be used for the firing atmosphere. The manufacturing process of zinc oxide powder in which is dissolved is complicated, and its manufacturing requires time and cost.

  In addition, the conventional conductive zinc oxide powder produced by the conventional manufacturing method as described above, in which aluminum is dissolved, as it is, has a characteristic that the volume resistivity increases with time in an air atmosphere at room temperature. It also has the problem of. It is oxygen deficiency that can be considered as a cause of the time-dependent change in volume resistivity of conductive zinc oxide powder in which conventional aluminum is dissolved. Conventional conductive zinc oxide powder has an oxygen deficiency due to being manufactured by firing in a reducing gas atmosphere, and therefore has a conduction mechanism due to oxygen deficiency in addition to a conduction mechanism due to solid solution of aluminum. . Since the oxygen deficiency of the conductive zinc oxide powder is likely to be reduced by exposure to the atmosphere even at room temperature, the volume resistivity of the conventional conductive zinc oxide powder is considered to increase with time in the air atmosphere.

  As a method for suppressing such deterioration of volume resistivity over time, Patent Document 4 discloses a reaction between a solution containing a metal water-soluble metal compound and an alkaline aqueous solution, wherein the pH of the reaction system is 6 to 12.5. A method for producing zinc oxide powder in which aluminum is dissolved is disclosed, in which both solutions are added in parallel so as to have a predetermined pH value in the range, and the resulting coprecipitate is fired in a reducing atmosphere. Since this manufacturing method can increase the solid solution ratio of aluminum in zinc oxide, it can relatively reduce the influence of oxygen deficiency on conductivity, and has a certain effect on suppressing the temporal deterioration of volume resistivity. It is believed that there is. However, it is necessary to mix while strictly adjusting the pH of the raw material solution, and this manufacturing process is complicated and difficult to manage.

  Conventionally, zinc oxide powder in which aluminum is dissolved is manufactured by the complicated process as described above. For example, in a simple method, for example, a method of mixing and baking zinc oxide and a conventional aluminum source, This is because a practical conductive zinc oxide powder cannot be obtained. As long as a conventional aluminum source is used, the conductive zinc oxide powder obtained by such a simple method does not exhibit a practically low volume resistivity, or volume resistivity over time even in an air atmosphere at room temperature. The rise is particularly noticeable. In a simple manufacturing method in which zinc oxide and a conventional aluminum source are simply mixed and fired, it is difficult to dissolve aluminum in the obtained zinc oxide powder, and oxygen deficiency is particularly likely to occur. Inferred. In some cases, only oxygen vacancies serve as carriers, and the resulting conductive zinc oxide powder may temporarily exhibit a low volume resistivity immediately after production. However, in the air atmosphere, oxygen vacancies gradually disappear over time. It is estimated that the volume resistivity increases and the volume resistivity increases.

  Accordingly, the present invention provides a simple method for producing a conductive zinc oxide powder having a low volume resistivity and little deterioration over time, and a solid solution of aluminum, and a novel aluminum solid solution oxidation obtained by the production method. An object is to provide zinc powder.

  In view of the above problems, the present inventors have conducted intensive studies. As a result, when an Al—N—H compound powder containing an imide group and / or an amide group is used as an aluminum source, zinc oxide powder and aluminum imide powder are used. Even with a simple manufacturing method that mixes and fires in an inert atmosphere, that is, a manufacturing method that does not require a disintegrant or a complicated process, a large amount of aluminum can be dissolved in zinc oxide, and the volume resistivity can be reduced. It has been found that low conductive zinc oxide powder can be produced. Furthermore, the zinc oxide powder in which aluminum is solid solution obtained by this production method is a novel conductive zinc oxide powder in which a specific proportion of nitrogen is also solid dissolved, and the volume resistivity changes with time. I found out that there was little, and came to the present invention.

  That is, the present invention is characterized in that zinc oxide powder and Al—N—H compound powder containing imide group and / or amide group are mixed and fired in the range of 900 to 1200 ° C. in an inert atmosphere. The present invention relates to a method for producing conductive zinc oxide powder.

  The present invention also provides an Al—N—H-based compound powder containing an imide group and / or an amide group in a ratio of 0.5 mol% to 10 mol% in terms of aluminum based on the zinc oxide powder and the zinc oxide powder. It is related with the manufacturing method of the said electroconductive zinc oxide powder characterized by mixing these.

  In addition, the present invention provides the zinc oxide powder and an Al—N—H-based compound powder containing the imide group and / or amide group at a ratio of 2 mol% to 10 mol% in terms of aluminum based on the zinc oxide powder. It is related with the manufacturing method of the said electroconductive zinc oxide powder characterized by mixing.

  The present invention also provides the production of the conductive zinc oxide powder, wherein the carbon impurity concentration of the Al—N—H compound powder containing the imide group and / or amide group is 2% or less on a mass basis. Regarding the method.

  The present invention also relates to a conductive zinc oxide powder characterized by solid solution of aluminum and nitrogen.

  The present invention also relates to the conductive zinc oxide powder, wherein aluminum is dissolved in a proportion of 0.01% by mass to 1.00% by mass with respect to zinc oxide.

  The present invention also relates to the conductive zinc oxide powder, wherein nitrogen is solid-dissolved in a proportion of 0.02 to 0.40% by mass with respect to zinc oxide.

  In the present invention, aluminum is solid-solved in a proportion of 0.3% to 1.00% by mass with respect to zinc oxide, and nitrogen is 0.1% to 0.40% by mass with respect to zinc oxide. It is related with the said electroconductive zinc oxide powder characterized by the above-mentioned.

The present invention has a specific surface area of 3.00m ² /g~5.00m ² / g, related to the electroconductive zinc oxide powder, wherein a volume resistivity of not more than 100 [Omega · cm.

  ADVANTAGE OF THE INVENTION According to this invention, the simple manufacturing method of the electroconductive zinc oxide powder with which the volume resistivity is low and there are few the time-dependent changes with which aluminum was dissolved can be provided. Moreover, the novel electroconductive zinc oxide powder in which both aluminum and nitrogen obtained by the manufacturing method can be provided.

It is an X-ray diffraction pattern of the electroconductive zinc oxide powder of Examples 1-4. 2 is an NMR spectrum diagram of the conductive zinc oxide powder of Example 1. FIG. 2 is a Raman spectrum diagram of conductive zinc oxide powder of Example 1. FIG. 4 is an X-ray diffraction pattern of a fixed material of a crucible after firing, obtained in Comparative Example 2. FIG. It is an X-ray diffraction pattern of the electroconductive zinc oxide powder of Comparative Examples 3-6. 4 is an NMR spectrum diagram of conductive zinc oxide powder of Comparative Example 3. FIG. 4 is a Raman spectrum diagram of conductive zinc oxide powder of Comparative Example 3. FIG. 4 is an NMR spectrum diagram of a conductive zinc oxide powder of Comparative Example 4. FIG. 6 is a Raman spectrum diagram of conductive zinc oxide powder of Comparative Example 4. FIG. 6 is an NMR spectrum diagram of conductive zinc oxide powder of Comparative Example 5. FIG. 6 is a Raman spectrum diagram of conductive zinc oxide powder of Comparative Example 5. FIG. 4 is an NMR spectrum diagram of conductive zinc oxide powder of Comparative Example 6. FIG. 6 is a Raman spectrum diagram of conductive zinc oxide powder of Comparative Example 6. FIG. It is a fluorescence spectrum figure of the electroconductive zinc oxide powder of Example 1 and Comparative Examples 3-6.

  First, the manufacturing method of the electroconductive zinc oxide powder of this invention is demonstrated.

  The method for producing a conductive zinc oxide powder of the present invention includes a zinc oxide powder and an Al—N—H compound powder containing an imide group and / or an amide group (hereinafter referred to as an Al—N—H compound powder). Are mixed and fired in the range of 900 to 1200 ° C. in an inert atmosphere.

  The zinc oxide powder used in the present invention is not particularly limited. For example, the French method in which zinc is melted and evaporated to be oxidized in the gas phase, the American method in which zinc ore is calcined and reduced and then oxidized is known. Zinc oxide powder produced by the above method can be used. Particular preference is given to using zinc oxide powder produced by the French method. This is because the zinc oxide powder produced by the French method has a uniform particle size and higher purity than the zinc oxide powder produced by the American method.

The Al—N—H-based compound powder used in the present invention is composed of an Al element, an N element, and an H element, and contains an imide group (—NH) and / or an amide group (—NH ₂ ). A powder composed of a compound bonded to one or more aluminum atoms. The Al—N—H compound powder used in the present invention may contain groups other than these as long as it contains an imide group and / or an amide group. For example, _Al 2 _{(NH) 3} having only an imide group, in addition to Al _{(NH) 3} with only amide group _may be a compound such as _{Al (C 2 H 5) (} NH). A compound containing both an imide group and an amide group may be used as long as at least one of the imide group and the amide group is bonded to an aluminum atom.

Particularly preferred as the Al—N—H compound powder used in the present invention is a triethylaluminum (Al (C ₂ H ₅ ) ₃ ) hexane (C ₆ H ₁₄ ) solution and ammonia in a sealed reaction vessel. After reacting with a decane (C ₁₀ H ₂₂ ) solvent, the Al—N—CH-based compound powder obtained by distilling off decane is heated under an ammonia stream, and the Al— containing an imide group is obtained. N—H compound powder. Here, the Al—N—CH-based compound powder is a powder of a compound containing one or more imide groups bonded to aluminum atoms and one or more ethyl groups bonded to aluminum atoms. Since the Al—N—H compound powder obtained by this method has a small amount of carbon impurities, metal impurities, and oxygen impurities, it can be used as an aluminum source to obtain high-purity conductive zinc oxide powder. If such a conductive zinc oxide powder is used, a high-purity target sintered body can be obtained, so that a transparent electrode film having particularly good transparency can be formed.

In the present invention, the mixing ratio of the zinc oxide powder and the Al—N—H compound powder is such that the ratio of the Al—N—H compound powder is 0.5 mol% to 10 mol% in terms of aluminum with respect to the zinc oxide powder. It is preferable that When the ratio of Al—N—H compound powder to zinc oxide powder is 0.5 mol% or more in terms of aluminum, the solid solution ratio of aluminum to zinc oxide can be increased, and the volume resistivity of the resulting conductive zinc oxide powder Is lower. Further, when the ratio of the Al—N—H compound powder to the zinc oxide powder is 10 mol% or less, for example, a compound having low conductivity such as a compound represented by the general formula: ZnAl ₂ O ₄ is hardly generated. Therefore, the volume resistivity of the obtained conductive zinc oxide powder tends to be low. The mixing ratio of zinc oxide powder and Al—N—H compound powder is more preferably 2 mol% to 10 mol% in terms of aluminum, and 6 mol% to 10 mol%. It is particularly preferred. The volume resistivity is particularly low when the mixing ratio of the zinc oxide powder and the Al—N—H compound powder is such that the ratio of the Al—N—H compound powder is in the range of 6 mol% to 10 mol% in terms of aluminum. In particular, it is possible to obtain a conductive zinc oxide powder with little change in volume resistivity with time.

  The carbon impurity concentration of the Al—N—H-based compound powder is preferably 2% or less on a mass basis. When the carbon impurity concentration of the Al—N—H compound powder is 2% or less on a mass basis, a conductive zinc oxide powder having a particularly low carbon impurity concentration can be obtained. If such a conductive zinc oxide powder is used, a target sintered body having a particularly low carbon impurity concentration can be obtained, so that a transparent electrode film having particularly good transparency can be formed.

  The above-described zinc oxide powder and the above-mentioned Al—N—H-based compound powder are weighed and mixed in an inert atmosphere. The mixing method is not particularly limited, but is preferably a method of mixing in a nitrogen atmosphere by a dry mill such as a mixer mill or a vibration mill in which the pot is replaced with nitrogen.

  The mixed powder obtained by mixing by the above method is baked in the range of 900 ° C. to 1200 ° C. in an inert atmosphere to obtain the conductive zinc oxide powder of the present invention. In order to suppress oxidation of the Al—N—H compound powder in the mixed powder, the mixed powder is fired in an inert atmosphere, preferably in a nitrogen atmosphere. As the firing furnace, a resistance heating type electric furnace, an induction heating type electric furnace, or the like that can be fired in an inert atmosphere can be used. Usually, a mixed powder contained in a boron nitride crucible is used as the electric furnace. Baking in an inert atmosphere, preferably in a nitrogen atmosphere, using a furnace. When the firing temperature is lower than 900 ° C., aluminum hardly dissolves in the fired zinc oxide powder, and thus the volume resistivity of the obtained conductive zinc oxide powder becomes high. Also, the firing temperature cannot be higher than 1200 ° C. This is because there is no crucible that does not react with either zinc oxide or Al—N—H-based compounds at a temperature higher than 1200 ° C., and neither of them changes in quality. At temperatures higher than 1200 ° C., the boron nitride crucible reacts with zinc oxide, the carbon crucible reduces zinc oxide to zinc, and other oxide crucibles and refractory metal crucibles are Al—N— Reacts with H compounds.

  When an Al—N—H compound powder is used as the aluminum source, the zinc oxide powder and the Al—N—H compound powder can be mixed without using a disintegrant represented by ammonium bicarbonate. Thus, aluminum in a proportion capable of expressing a practical volume resistivity can be dissolved in the zinc oxide powder by a method of merely firing in the range of 900 to 1200 ° C. in an inert atmosphere. In other words, the zinc oxide powder can be put to practical use by simply mixing and firing the raw material powder without the need to perform stirring, filtration, drying, etc. in the solution to react the disintegrant with zinc oxide. A ratio of aluminum capable of exhibiting a specific volume resistivity can be dissolved. This simple method allows aluminum to be dissolved in zinc oxide powder when the imide group or amide group is desorbed from the Al—N—H compound powder at a high temperature during firing. The structure of zinc oxide collapses even in the gas phase due to ammonia, and at the same time, aluminum generated by elimination of the imide group or amide group is supplied to the collapsed part, so that the zinc oxide powder This is thought to be because the solid solution of aluminum is promoted.

  In addition, when a mixed powder composed of zinc oxide powder and Al—N—H compound powder is fired in an inert atmosphere in the range of 900 to 1200 ° C., novel conductivity is obtained in which both aluminum and nitrogen are dissolved. Zinc oxide powder can be obtained.

  When a mixed powder composed of zinc oxide powder and Al—N—H-based compound powder is fired in the range of 900 to 1200 ° C. in an inert atmosphere, both aluminum and nitrogen are dissolved in zinc oxide. When the structure of zinc oxide collapses due to ammonia generated when the imide group or amide group is desorbed from the Al—N—H-based compound powder at a high temperature, the nitrogen desorbed from the ammonia is It is thought that this is because a reaction peculiar to the present invention occurs in which aluminum and nitrogen are simultaneously dissolved in zinc oxide and aluminum and nitrogen are simultaneously dissolved in zinc oxide, but the mechanism is not clear.

  Next, the conductive zinc oxide powder of the present invention obtained by the production method of the present invention described above will be described.

  The electrically conductive zinc oxide powder of the present invention is a novel electrically conductive zinc oxide powder in which aluminum and nitrogen are solid-dissolved and the change in volume resistivity with time is very small. And it is guessed that the volume resistivity of the electroconductive zinc oxide powder of this invention hardly changes with time that not only aluminum but solid nitrogen is dissolved in zinc oxide. Zinc oxide is an oxide that is easily reduced. Even if the atmosphere during firing is an inert atmosphere, it is not as much as a reducing atmosphere, but it is considered that some oxygen is released from zinc oxide during firing. . However, in the present invention, it is presumed that, during firing, nitrogen is dissolved in lattice vacancies generated by desorption of oxygen, and apparently there is obtained zinc oxide having almost no oxygen vacancies, that is, almost no lattice vacancies. Is done.

  Further, the fact that aluminum which is an n-type dopant and nitrogen which is a p-type dopant are simultaneously dissolved in zinc oxide increases the stability of the crystal structure of the conductive zinc oxide powder of the present invention, It is presumed that the time-dependent change in volume resistivity of the conductive zinc oxide powder of the present invention is suppressed. In the conductive zinc oxide powder of the present invention, since the aluminum ion of the n-type dopant and the nitrogen ion of the p-type dopant are both in solid solution, an electrostatic interaction gain is obtained by the Coulomb attractive force of both ions. It is considered that the increase in lattice energy is suppressed and the stability of the crystal structure is enhanced. As a result, slight changes such as the chemical state of the dopant are also suppressed, and it is presumed that the volume resistivity of the conductive zinc oxide powder of the present invention hardly changes with time.

  In the conductive zinc oxide powder of the present invention, it is preferable that aluminum is dissolved in a proportion of 0.01% by mass to 1.00% by mass with respect to zinc oxide. When the solid solution ratio of aluminum to zinc oxide is within this range, a conductive zinc oxide powder having a volume resistivity of 100 Ω · cm or less can be obtained.

  In the conductive zinc oxide powder of the present invention, nitrogen is preferably dissolved in a proportion of 0.02% by mass to 0.40% by mass with respect to zinc oxide. When the solid solution ratio of nitrogen to zinc oxide is within this range, the volume resistivity of the conductive zinc oxide powder is not increased, and the change in volume resistivity with time (the volume resistivity increases with time) is suppressed. be able to. Furthermore, aluminum is solid-solved at a rate of 0.3% to 1.00% by mass with respect to zinc oxide, and nitrogen is at a rate of 0.1% to 0.40% by mass with respect to zinc oxide. It is preferable that it is dissolved.

The electroconductive zinc oxide powder of the present invention has a specific surface area of 3.00m ² /g~5.00m ² / g, it preferably has a volume resistivity of not more than 100 [Omega · cm. When the specific surface area is less than 3.00 m ² / g, molding becomes difficult, and it becomes difficult to produce a sintered compact target when used for forming a transparent conductive film. Further, if the specific surface area is larger than 5.00 m ² / g, the volume resistivity may not be the target of 100 Ω · cm or less.

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

(Measurement method of specific surface area of conductive zinc oxide powder)
The specific surface area of the conductive zinc oxide powder of the present invention was measured with a Flowsorb III 2310 apparatus manufactured by Shimadzu-Micromeritics after the powder was filled in a glass cell.

(Measurement method of aluminum solid solution ratio in conductive zinc oxide powder)
The solid solution ratio of aluminum in the conductive zinc oxide powder of the present invention was measured by the method described below.

  The proportion of aluminum dissolved in the conductive zinc oxide powder of the present invention is determined by the solid oxide in the total amount of aluminum in the conductive zinc oxide powder obtained by solid state NMR analysis (solid nuclear magnetic resonance spectroscopy) of aluminum. It calculated by multiplying the ratio of the melted aluminum and the content ratio of aluminum in the conductive zinc oxide powder obtained by ICP-AES (luminescence analysis using inductively coupled plasma). This will be specifically described below.

  The conductive zinc oxide powder of the present invention and the zinc oxide powder of the comparative example were heated and dissolved with nitric acid, hydrofluoric acid, and sulfuric acid, and the resulting solution was converted to an SPS5100 type ICP emission spectrometer manufactured by SII Nanotechnology. It used for the ICP emission analysis used, and measured the content rate of the total aluminum in electroconductive zinc oxide powder. In addition, the conductive zinc oxide powder of the present invention and the zinc oxide powder of the comparative example were subjected to solid state NMR analysis using a JNM-ECA400 type FT-NMR apparatus manufactured by JEOL, and derived from aluminum in the obtained NMR spectrum. The ratio of the aluminum dissolved in zinc oxide to the total aluminum in the (conductive) zinc oxide powder was determined from the ratio of the peak area derived from aluminum dissolved in zinc oxide to the area of all peaks. .

  By multiplying the aluminum content in the conductive zinc oxide powder obtained as described above and the ratio of aluminum dissolved in zinc oxide to the total aluminum in the conductive zinc oxide powder, the conductivity of the present invention is obtained. The proportion of aluminum dissolved in the zinc oxide powder and the zinc oxide powder of the comparative example was calculated.

(Measurement method of solid solution ratio of nitrogen in conductive zinc oxide powder)
The solid solution ratio of nitrogen in the conductive zinc oxide powder of the present invention was measured by the method described below.

  First, the Raman spectrum of the conductive zinc oxide powder of the present invention obtained by Raman spectroscopic analysis using JASCO Corporation laser Raman spectrometer has a peak derived from the solid solution of nitrogen in zinc oxide. It was confirmed. Next, the conductive zinc oxide powder of the present invention is put into a graphite crucible, heated and melted using a LECO oxygen / nitrogen / hydrogen analyzer TCH600, and the nitrogen generated from the melted sample is provided in the analyzer. The nitrogen content ratio of the conductive zinc oxide powder of the present invention was measured by quantifying with a thermal conductivity detector. In addition, the NMR spectrum obtained by solid-state NMR analysis described in the above (Method for measuring the solid solution ratio of aluminum in conductive zinc oxide powder) is derived from 4-coordinate nitrogen indicating the formation of aluminum nitride. It was confirmed in all Examples that there was no peak around 100 ppm. From the above, it has been confirmed that all of the nitrogen detected by TCH600 is derived from nitrogen dissolved in the conductive zinc oxide powder of the present invention. The solid solution ratio was determined.

(Measurement method of volume resistivity of conductive zinc oxide powder)
The conductive zinc oxide powder of the present invention is filled into a cylindrical mold with an inner diameter of 20 mm made of Teflon (registered trademark) having a cross-sectional area of π cm ² , and a pressure of 10 MPa is applied to form a disk-shaped green compact. Molded. About the obtained green compact, the volume resistivity was measured at room temperature using the commercially available multimeter, and the value was made into the volume resistivity of the electroconductive zinc oxide powder of this invention. When measuring the volume resistivity of each conductive zinc oxide powder immediately after production, the volume resistivity of each conductive zinc oxide powder is taken out of the high frequency induction furnace in which the atmosphere during production is maintained and 24 hours have passed. Measurements were made.

(Evaluation method of change with time of volume resistivity of conductive zinc oxide powder)
4 g of the conductive zinc oxide powder immediately after production is contained in a polyethylene bag (with a chuck) having a capacity of 10 g in an air atmosphere at a temperature of 25 ° C. and a humidity of 50%. It preserve | saved in the atmospheric condition holding 50% of humidity. After 30 days and 210 days from immediately after production, the volume resistivity of the conductive zinc oxide powder is measured by the same method as described in (Method for measuring volume resistivity of conductive zinc oxide powder). The volume resistivity was compared.

(Production example)
As the Al—N—H compound powder according to the present invention, Al ₂ (NH) ₃ powder produced by the following method was used.

A three-way faucet for introducing gas, a sheath for a thermometer, and a fractionation tube combined with a two-necked eggplant flask with a capacity of 500 mL were installed in a glass three-neck flask having a capacity of 1000 mL. These instruments were sufficiently dried in an oven at 130 ° C. in advance, and further assembled, and then heated with a hot blaster under vacuum to remove moisture adhering to the inner wall surface. The apparatus thus dried and sealed with the inside kept in an N ₂ gas atmosphere was placed in a glove box having the same N ₂ atmosphere. After measuring the oxygen concentration and dew point of the glove box outlet gas and confirming that the atmosphere is low in oxygen and moisture, 200 mL of triethylaluminum hexane solution (manufactured by Wako Pure Chemical Industries, Ltd., triethylaluminum concentration: 1 mol / L) was added. Was introduced into a glass three-necked flask having a volume of 1000 mL. Next, 200 mL of decane (moisture of 10 ppm or less) was introduced and mixed well, and then the entire glass apparatus was kept sealed and taken out from the glove box.

  While heating a 1000 mL glass three-necked flask with an oil bath, ammonia gas was bubbled into the triethylaluminum solution inside. The flow rate of the ammonia gas supply was 100 mL / min (25 ° C., normal pressure), and the internal liquid was stirred with a magnetic stirrer. First, the oil bath temperature was maintained at 120 ° C., hexane in the reaction mixture was distilled off, and the mixture was received in a 500 mL two-necked eggplant flask connected to a fractionating tube. After the distillation of hexane was completed, when the oil bath temperature was raised to 180 ° C., a white precipitate began to precipitate, confirming the progress of the reaction. The reaction was carried out for 4 hours at an oil bath temperature of 180 ° C. (slurry temperature in the flask: 170 ° C.) while continuously supplying ammonia gas.

Next, the oil bath temperature was raised to 200 ° C., and decane was distilled off from the slurry containing the produced white precipitate. Ammonia gas was continuously supplied during the decane distillation operation. Next, the supply of ammonia gas was stopped, and the entire apparatus was sealed and placed in a glove box to recover 15.16 g of a white solid mainly composed of (C ₂ H ₅ ) Al (NH). The amount of Al in the white solid was analyzed to be 37.8% by mass by CyDTA-zinc back titration method (based on JIS R1675: 2007), and the amount of N was determined by direct decomposition-steam distillation-neutralization titration method (JIS R1675: 2007). 19.9% by mass). A small amount of this white solid was collected and hydrolyzed with a water / propanol mixture. The generated gas was collected, analyzed by gas chromatography, and quantified by the absolute calibration curve method. As a result, 12.4 mmol of ethane was detected per 1 g of the white solid, and the molar ratio of ethyl group to Al in the white solid was ethyl. Calculated as group / Al = 0.89 (mol / mol). These values agree well with the theoretical values (Al: 38.0% by mass, N: 19.7% by mass, ethyl group / Al = 1) in the composition formula (C ₂ H ₅ ) Al (NH). Yes. On the other hand, the measurement of the IR spectrum of the white in a solid, a peak attributed to N-H bonds to 3263cm ^-1 and 1554cm ^-1 were detected. Further, when 1H-NMR measurement of this solid was carried out by ECA-400 type manufactured by JEOL, a broad signal having an apex at a position of δ 0.72 ppm was observed (external reference material: trimethylsilylpropanoate heavy aqueous solution). . These are believed to originate from H on the ethyl and imide groups.

In the glove box, 6.17 g of the white solid synthesized above was filled into a U-shaped glass tube having an inner diameter of 17 mm with a three-way cock installed at both ends. The three-way cock and the glass tube are dried by the same method as the glass apparatus used for the reaction of the organoaluminum compound solution and ammonia. A heater was attached to the glass tube, and the white solid packed layer was heated while ammonia gas was supplied from one cock and discharged from the other cock. At this time, the flow rate of ammonia gas supply is 100 mL / min (25 ° C., normal pressure), the heater temperature is 240 ° C., and the superficial velocity of the supplied ammonia is 1.3 cm / s. Heating was terminated after 6 hours, and a white solid composed of Al ₂ (NH) ₃ was collected in the glove box. The yield is 4.26 g, and the mass change rate before and after the treatment is 69.0%, which is in good agreement with the theoretical value 69.7% of the solid component mass change rate based on the following reaction formula, formula (1). Indicated.
2 (C ₂ H ₅ ) Al (NH) + NH ₃ → Al ₂ (NH) ₃ + 2C ₂ H ₆ (1)

The Al concentration determined by the CyDTA-zinc back titration method was 55.8% by mass (calculated value with composition formula Al ₂ (NH) ₃ : 54.5% by mass). From the IR spectrum measurement, peaks attributed to N—H bonds were detected at 3227 cm ⁻¹ and 1539 cm ⁻¹ . A small amount of this white solid was collected, hydrolyzed with a water / propanol mixture, and the generated gas was collected and analyzed by gas chromatography. The amount of ethane detected was as low as 0.52 mmol per 1 g of white solid. there were. From these results, the molar ratio of ethyl group to Al in the white solid was ethyl group / Al = 0.03 (mol / mol), and the carbon impurity concentration in the white solid was calculated to be 1.2% by mass. . The amount of impurity oxygen was 1.4% by mass when analyzed by an infrared absorption method using a TCH-600 type oxygen / nitrogen / hydrogen analyzer manufactured by LECO. When metal impurities were examined by fluorescent X-ray analysis, the Al concentration in the metal component was 99.7% by mass and substantially no metal impurities were present. When a specific surface area was measured by a BET one-point method using Shimadzu-Micromeritics Flowsorb III2310, it was 868 m ² / g. Further, when 1H-NMR measurement of this solid was carried out by ECA-400 type manufactured by JEOL, a broad signal having an apex at a position of δ0.97 ppm was observed (external reference substance: trimethylsilylpropanoate heavy aqueous solution). . This is considered to originate from H on the imide group.

When 0.4708 g of this product was placed in a BN crucible and fired at 1600 ° C. for 2 hours in an N ₂ gas atmosphere, 0.3915 g of powder was obtained. The powder was identified as AlN by XRD analysis, and no other crystal phase was observed. Elemental analysis results also showed good agreement with AlN as follows; Al (measured by CyDTA-zinc back titration method): 65.0 mass% (calculated value 65.9 mass%), N (LECO TCH-600 Measured by electrical conductivity method using a type oxygen / nitrogen / hydrogen analyzer): 33.8% by mass (calculated value 34.1% by mass). Moreover, the mass ratio of the product recovered after firing with respect to the used raw material was 83.2%. This supports that the following reaction formula, Formula (2), has progressed quantitatively, and it can be confirmed that the white solid before firing is represented by the composition formula Al ₂ (NH) _3. It was.
Al ₂ (NH) ₃ → 2AlN + NH ₃ (2)

Example 1
As an aluminum source, 5 mol of Al ₂ (NH) ₃ powder obtained in (Production Example) and 90 mol of zinc oxide powder (NanoTek (registered trademark) manufactured by Kanto Chemical Co., Ltd.) were used as raw material powders. 1 conductive zinc oxide powder was produced. The raw material powder was weighed so that the sum of the raw material powder was 4 g, and was housed in a stainless steel pot together with a nylon ball in a nitrogen atmosphere glove box, and the stainless steel pot was sealed so that the nitrogen atmosphere in the pot was maintained. . The stainless steel pot was vibrated at a frequency of 15 Hz for 30 minutes using a Retsch mixer mill to mix the raw material powder. In a glove box in a nitrogen atmosphere, the stainless steel pot was opened, and the obtained mixed powder was taken out of the stainless steel pot and accommodated in a boron nitride crucible. Further, the boron nitride crucible is accommodated in a graphite crucible, heated from a room temperature to 1000 ° C. at a heating rate of 1000 ° C./hour in a nitrogen atmosphere using a high frequency induction furnace, and held at 1000 ° C. for 10 minutes. The mixed powder was fired. The fired powder was pulverized using an alumina mortar and an alumina pestle to obtain conductive zinc oxide powder of Example 1.

  The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Example 1 is shown in FIG. From FIG. 1, a diffraction peak derived from zinc oxide was observed, and it was confirmed that the obtained powder was composed of zinc oxide.

  Next, the solid solution ratio of aluminum in the obtained conductive zinc oxide powder was measured by the method described above (Method for measuring the solid solution ratio of aluminum in the conductive zinc oxide powder). First, the NMR spectrum of the conductive zinc oxide powder of Example 1 was obtained by solid state NMR analysis. The NMR spectrum of the conductive zinc oxide powder obtained in Example 1 is shown in FIG. From FIG. 2, an NMR spectrum having a peak around 200 ppm indicating the solid solution of aluminum in zinc oxide is observed, and aluminum is dissolved in the zinc oxide of the conductive zinc oxide powder of Example 1. Was confirmed. Further, from the obtained NMR spectrum, the ratio of the area of the peak derived from aluminum dissolved in zinc oxide to the area of all the peaks derived from aluminum was calculated, and in the conductive zinc oxide powder of Example 1 The ratio of aluminum dissolved in zinc oxide to the total aluminum was calculated as 28.29%. Subsequently, the content rate of the total aluminum in the electroconductive zinc oxide powder of Example 1 was measured by ICP emission analysis. The total aluminum content in the conductive zinc oxide powder of Example 1 obtained by ICP emission analysis was 3.5% by mass, and the total amount of aluminum dissolved in zinc oxide was obtained by NMR spectrum. By multiplying the ratio by 28.29%, the solid solution ratio of aluminum in the conductive zinc oxide powder of Example 1 was calculated. The result was 0.990 mass% as shown in Table 1.

Further, the solid solution ratio of nitrogen in the obtained conductive zinc oxide powder was measured by the method described in (Method for measuring the solid solution ratio of nitrogen in the conductive zinc oxide powder). First, the Raman spectrum of the conductive zinc oxide powder of Example 1 was obtained by Raman spectroscopy. The Raman spectrum of the obtained conductive zinc oxide powder of Example 1 is shown in FIG. From Figure ^3, 275cm -1 derived from the dissolution of nitrogen into zinc ^{oxide, 508cm -1, 579cm -1,} it is confirmed that the 642 cm ^-1 around peaks (see Non-Patent Documents 1 and 2) are present It was. Next, the content ratio of nitrogen in the conductive zinc oxide powder of Example 1 was measured using an oxygen / nitrogen / hydrogen analyzer. Further, it was confirmed that there was no peak near 100 ppm indicating the formation of aluminum nitride in the NMR spectrum used for measuring the solid solution ratio of aluminum in the conductive zinc oxide powder of Example 1. Nitrogen in the conductive zinc oxide powder of Example 1 cannot exist except for forming a solid solution in zinc oxide or forming aluminum nitride. Therefore, in the conductive zinc oxide powder of Example 1, oxidation is not possible. It was determined that there was no nitrogen other than solid solution in zinc, and the content ratio of nitrogen in the conductive zinc oxide powder of Example 1 obtained using an oxygen / nitrogen / hydrogen analyzer was 0.314% by mass. As shown in Table 1, the solid solution ratio of nitrogen in the conductive zinc oxide powder of Example 1 was used.

The specific surface area of the conductive zinc oxide powder of Example 1 was measured using a Flowsorb 2310 manufactured by Shimadzu Corporation. The result was 4.73 m ² / g as shown in Table 1.

  Next, 2 g of the conductive zinc oxide powder of Example 1 was filled in a 20 mm inner diameter cylinder made of Teflon (registered trademark) and pressure-molded at a pressure of 10 MPa, and the volume resistivity of the obtained green compact was determined. The measurement was performed at room temperature using a “volume resistivity measuring device” manufactured by Toyo Technica. As shown in Table 1, the volume resistivity at room temperature of the conductive zinc oxide powder of Example 1 immediately after production was 10.6 Ω · cm. Furthermore, the electroconductive zinc oxide powder of Example 1 was preserve | saved by the method demonstrated by the above-mentioned (Evaluation method of the time-dependent change of the volume resistivity of electroconductive zinc oxide powder), and 30 days passed after manufacture. Also about the electroconductive zinc oxide powder of Example 1 after 30-day progress, the volume resistivity was measured by the method similar to immediately after manufacture. As shown in Table 1, the volume resistivity of the conductive zinc oxide powder of Example 1 after 30 days was 12.7 Ω · cm, and it was confirmed that there was almost no change in volume resistivity with time.

  Further, in the same manner as the method in which the conductive zinc oxide powder of Example 1 was allowed to elapse for 30 days from immediately after production, 210 days had elapsed since immediately after production, and in the same manner as the measurement of volume resistivity immediately after production, 210 days passed. The volume resistivity of the conductive zinc oxide powder of Example 1 was measured. The volume resistivity of the conductive zinc oxide powder of Example 1 after 210 days was 15.4 Ω · cm as shown in Table 1, and it was confirmed that there was almost no change in volume resistivity with time even after 210 days. It was done.

  In addition, the fluorescence spectrum of the conductive zinc oxide powder of Example 1 was measured to check for the presence of lattice vacancies (oxygen vacancies). If zinc oxide has lattice vacancies (oxygen vacancies), it is known that conductivity is temporarily exhibited until the lattice vacancies (oxygen vacancies) are filled. This is because it is confirmed that the zinc oxide powder exhibits a low volume resistivity due to the solid solution of aluminum. Generally, it is known that if there are lattice vacancies (oxygen vacancies) in zinc oxide, a peak appears in the vicinity of 500 nm of the fluorescence spectrum. Using the fluorescent spectrophotometer FP-6500 manufactured by JASCO Corporation, the conductive zinc oxide powder of Example 1 housed in a powder sample holder having a light-receiving portion made of quartz glass in an integrating sphere attached thereto. The fluorescence spectrum of the conductive zinc oxide powder of Example 1 was measured by irradiation with light of 320 nm. The results are shown in FIG. 14 together with the fluorescence spectra of the conductive zinc oxide powders of Comparative Examples 3, 4, 5, and 6. In the fluorescence spectra of the conductive zinc oxide powders of Comparative Examples 3, 4, 5, and 6, a peak was observed at around 500 nm, but in the fluorescence spectrum of the conductive zinc oxide powder of Example 1, a peak around 500 nm was observed. Not observed. It can be seen that the conductive zinc oxide powder of Example 1 has almost no lattice vacancies (oxygen vacancies), and the low volume resistivity is attributed to the solid solution of aluminum in zinc oxide. confirmed.

(Example 2)
A conductive zinc oxide powder of Example 2 was produced in the same manner as in Example 1 except that the raw material powder was 1 mol of Al ₂ (NH) ₃ powder and 98 mol of zinc oxide powder. About the obtained conductive zinc oxide powder of Example 2, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen were performed in the same manner as in Example 1. The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Example 2 is shown in FIG. From the result of X-ray diffraction analysis, as shown in FIG. 1, it was found that a diffraction peak due to zinc oxide was observed, and that the obtained powder was composed of zinc oxide. Table 1 shows the specific surface area of the conductive zinc oxide powder of Example 2, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Example 2 was 3.76 m ² / g, the solid solution ratio of aluminum was 0.143 mass%, and the solid solution ratio of nitrogen was 0.030 mass%. The volume resistivity was 54.9 Ω · cm immediately after production, 65.4 Ω · cm after 30 days, and 84.8 Ω · cm after 210 days. It remained at a low value of 100 Ω · cm or less.

(Example 3)
A conductive zinc oxide powder of Example 3 was produced in the same manner as in Example 1 except that the raw material powder was ₃ mol of Al ₂ (NH) ₃ powder and 94 mol of zinc oxide powder. About the obtained conductive zinc oxide powder of Example 3, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen were performed in the same manner as in Example 1. The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Example 3 is shown in FIG. From the result of the X-ray diffraction analysis, as shown in FIG. 1, a diffraction peak derived from zinc oxide was observed, and it was found that the obtained powder was composed of zinc oxide. Table 1 shows the specific surface area of the conductive zinc oxide powder of Example 3, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Example 3 was 3.48 m ² / g, the solid solution ratio of aluminum was 0.331 mass%, and the solid solution ratio of nitrogen was 0.130 mass%. The volume resistivity is 17.7 Ω · cm immediately after production, 17.3 Ω · cm after 30 days, 14.0 Ω · cm after 210 days, and particularly low volume resistivity, even after 210 days. It was confirmed that there was almost no change over time.

Example 4
A conductive zinc oxide powder of Example 4 was produced in the same manner as in Example 1 except that the firing temperature of the mixed powder (maximum temperature during firing) was 1100 ° C. About the obtained conductive zinc oxide powder of Example 4, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen were performed in the same manner as in Example 1. The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Example 4 is shown in FIG. From the results of X-ray diffraction analysis, as shown in FIG. 1, a diffraction peak derived from zinc oxide was observed, and it was found that the obtained powder was composed of zinc oxide. Table 1 shows the specific surface area of the conductive zinc oxide powder of Example 4, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Example 4 was 3.80 m ² / g, the solid solution ratio of aluminum was 0.408 mass%, and the solid solution ratio of nitrogen was 0.174 mass%. The volume resistivity is 45.9 Ω · cm immediately after production, 41.8 Ω · cm after 30 days, 41.5 Ω · cm after 210 days, and a low volume resistivity of 100 Ω · cm or less. Even after 210 days, it was confirmed that there was almost no change over time.

(Comparative Example 1)
A conductive zinc oxide powder of Comparative Example 1 was produced in the same manner as in Example 1 except that the firing temperature of the mixed powder was 800 ° C. About the obtained conductive zinc oxide powder of Comparative Example 1, by the same method as Example 1, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 1 is shown in FIG. From the results of X-ray diffraction analysis, as shown in FIG. 4, it was found that a diffraction peak derived from zinc oxide was observed, and the obtained powder was composed of zinc oxide. Table 1 shows the specific surface area of the conductive zinc oxide powder of Comparative Example 1, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Comparative Example 1 was 7.37 m ² / g, the solid solution ratio of aluminum was 0 mass%, and the solid solution ratio of nitrogen was 1.21 mass%. Moreover, the volume resistivity was so high that it exceeded the measurement limit (1 × 10 ⁸ Ω · cm) of the measuring apparatus immediately after production, after 30 days and after 210 days.

(Comparative Example 2)
The mixed powder was fired by the same method as in Example 1 except that the firing temperature of the mixed powder was 1300 ° C. The sample of Comparative Example 2 after firing reacted with the boron nitride crucible to vitrify, and was fixed to the bottom of the boron nitride crucible. The fixed matter was crushed and subjected to X-ray diffraction analysis. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 2 is shown in FIG. As shown in FIG. 4, no diffraction peak derived from zinc oxide was observed, and no zinc oxide powder was obtained in Comparative Example 2 in which the firing temperature was 1300 ° C.

(Comparative Example 3)
The conductivity of Comparative Example 3 was the same as that of Example 1, except that the aluminum source was aluminum sulfate (Al ₂ (SO ₄ ) ₃ ) powder, and the raw material powder was 5 mol of aluminum sulfate powder and 90 mol of zinc oxide powder. Zinc oxide powder was produced. About the obtained conductive zinc oxide powder of Comparative Example 3, by the same method as Example 1, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 3 is shown in FIG. From the result of the X-ray diffraction analysis, as shown in FIG. 5, a diffraction peak derived from zinc oxide was observed. FIG. 6 shows the NMR spectrum of the conductive zinc oxide powder of Comparative Example 3 obtained. In the NMR spectrum of the conductive zinc oxide powder of Comparative Example 3, a peak is observed around 200 ppm indicating the solid solution of aluminum in zinc oxide, but it is compared with that of the NMR spectrum of the conductive zinc oxide powder of Example 1. It was a very small peak. In FIG. 7, the Raman spectrum of the electroconductive zinc oxide powder of the comparative example 3 is shown. In the Raman spectrum of the conductive zinc oxide powder of Comparative Example 3, no nitrogen solid solution peak as in Example 1 was observed.

Table 1 shows the specific surface area of the conductive zinc oxide powder of Comparative Example 3, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Comparative Example 3 was 2.70 m ² / g, the solid solution ratio of aluminum was 0.015 mass%, and the solid solution ratio of nitrogen was 0 mass%. In addition, the volume resistivity was as low as 37.9 Ω · cm immediately after manufacture, but 189.1 Ω · cm after 30 days, and the measurement limit (1 × 10 ⁸ Ω · cm) of the measuring device after 210 days. It was confirmed that the higher the value was, the remarkably changed with time. It turned out that the electroconductive zinc oxide powder of the comparative example 3 is not a practical electroconductive zinc oxide powder.

  Further, the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 3 was measured to examine the presence or absence of lattice vacancies (oxygen vacancies). The fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 3 was measured in the same manner as in Example 1. The results are shown in FIG. 14 together with the fluorescence spectra of the conductive zinc oxide powders of Example 1 and Comparative Examples 4, 5, and 6. In the fluorescence spectrum of the conductive zinc oxide powder of Example 1, no peak is observed in the vicinity of 500 nm, whereas in the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 3, it is 500 nm as in the other comparative examples. A peak was observed in the vicinity. The conductive zinc oxide powder of Comparative Example 3 has a low volume resistivity and exhibits electrical conductivity immediately after production, and the change over time is significant because the electrical conductivity of the conductive zinc oxide powder of Comparative Example 3 is a lattice. This is presumed to be due to vacancies (oxygen deficiency).

(Comparative Example 4)
The conductivity of Comparative Example 4 was the same as that of Example 1 except that the aluminum source was aluminum nitrate (Al (NO ₃ ) ₃ ) powder and the raw material powder was 10 mol of aluminum nitrate powder and 90 mol of zinc oxide powder. Zinc oxide powder was produced. About the obtained conductive zinc oxide powder of Comparative Example 4, by the same method as Example 1, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 4 is shown in FIG. From the result of the X-ray diffraction analysis, as shown in FIG. 5, a diffraction peak derived from zinc oxide was observed. FIG. 8 shows the NMR spectrum of the conductive zinc oxide powder of Comparative Example 4. In the NMR spectrum of the conductive zinc oxide powder of Comparative Example 4, a peak around 200 ppm indicating solid solution of aluminum in zinc oxide was not observed. In FIG. 9, the Raman spectrum of the electroconductive zinc oxide powder of the comparative example 4 is shown. In the Raman spectrum of the conductive zinc oxide powder of Comparative Example 4, no peak derived from nitrogen solid solution was observed. Table 1 shows the specific surface area of the conductive zinc oxide powder of Comparative Example 4, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Comparative Example 4 was 1.97 m ² / g, the solid solution ratio of aluminum was 0 mass%, and the solid solution ratio of nitrogen was 0.021 mass%. In addition, the volume resistivity is as high as 200.7 Ω · cm even immediately after production, and is further increased to 423.3 Ω · cm after 30 days. Further, after 210 days, the measurement limit (1 × 10 ⁸ Ω · cm It was confirmed that the value was higher as it exceeded (cm) and changed with time.

  In addition, the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 4 was measured to check for the presence of lattice vacancies (oxygen vacancies). The fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 3 was measured in the same manner as in Example 1. The results are shown in FIG. 14 together with the fluorescence spectra of the conductive zinc oxide powders of Example 1 and Comparative Examples 3, 5, and 6. In the fluorescence spectrum of the conductive zinc oxide powder of Example 1, no peak is observed in the vicinity of 500 nm, whereas the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 4 has a wavelength of 500 nm as in the other comparative examples. A peak was observed in the vicinity. The conductive zinc oxide powder of Comparative Example 4 exhibits a high volume resistivity immediately after production, and the change over time is remarkable because the conductivity of the conductive zinc oxide powder of Comparative Example 4 is lattice empty. This is presumed to be due to pores (oxygen deficiency).

(Comparative Example 5)
The conductive zinc oxide powder of Comparative Example 5 was prepared in the same manner as in Example 1 except that the aluminum source was aluminum chloride (AlCl ₃ ) powder and the raw material powder was 10 mol of aluminum chloride powder and 90 mol of zinc oxide powder. Manufactured. About the obtained conductive zinc oxide powder of Comparative Example 5, by the same method as Example 1, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 5 is shown in FIG. From the result of the X-ray diffraction analysis, as shown in FIG. 5, a diffraction peak derived from zinc oxide was observed. FIG. 10 shows the NMR spectrum of the conductive zinc oxide powder of Comparative Example 5. In the NMR spectrum of the conductive zinc oxide powder of Comparative Example 5, a peak around 200 ppm indicating solid solution of aluminum in zinc oxide was not observed. In FIG. 11, the Raman spectrum of the electroconductive zinc oxide powder of the comparative example 5 is shown. In the Raman spectrum of the conductive zinc oxide powder of Comparative Example 5, no peak derived from the solid solution of nitrogen was observed. Table 1 shows the specific surface area of the conductive zinc oxide powder of Comparative Example 5, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after production, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Comparative Example 5 was 2.32 m ² / g, the aluminum solid solution ratio was 0 mass%, and the nitrogen solid solution ratio was 0 mass%. In addition, the volume resistivity was as low as 94.1 Ω · cm immediately after manufacture, but increased to 191.0 Ω · cm after 30 days, and after 210 days, the measurement limit (1 × 10 ⁸ Ω · cm). It has been confirmed that it becomes higher as it exceeds cm) and changes with time.

  Further, the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 5 was measured to examine the presence or absence of lattice vacancies (oxygen vacancies). The fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 5 was measured in the same manner as in Example 1. The results are shown in FIG. 14 together with the fluorescence spectra of the conductive zinc oxide powders of Example 1 and Comparative Examples 3, 4, and 6. In the fluorescence spectrum of the conductive zinc oxide powder of Example 1, no peak is observed in the vicinity of 500 nm, whereas the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 5 is 500 nm as in the other comparative examples. A peak was observed in the vicinity. The conductive zinc oxide powder of Comparative Example 5 has a low volume resistivity and exhibits electrical conductivity immediately after production, and the change over time is significant because the conductivity of the conductive zinc oxide powder of Comparative Example 5 is a lattice. This is presumed to be due to vacancies (oxygen deficiency).

(Comparative Example 6)
A conductive zinc oxide powder of Comparative Example 6 is produced in the same manner as in Example 1 except that the aluminum source is aluminum nitride (AlN) powder and the raw material powder is 10 mol of aluminum nitride powder and 90 mol of zinc oxide powder. did. About the obtained conductive zinc oxide powder of Comparative Example 6, by the same method as in Example 1, X-ray diffraction analysis, measurement of specific surface area, measurement of solid solution ratio of aluminum, and measurement of solid solution ratio of nitrogen The volume resistivity was measured immediately after production, after 30 days and after 210 days. The result of the X-ray diffraction analysis of the obtained conductive zinc oxide powder of Comparative Example 6 is shown in FIG. From the result of the X-ray diffraction analysis, as shown in FIG. 5, a diffraction peak derived from zinc oxide was observed. FIG. 12 shows the NMR spectrum of the conductive zinc oxide powder of Comparative Example 4. In the NMR spectrum of the conductive zinc oxide powder of Comparative Example 6, a peak around 200 ppm indicating solid solution of aluminum in zinc oxide was not observed. In FIG. 13, the Raman spectrum of the electroconductive zinc oxide powder of the comparative example 6 is shown. In the Raman spectrum of the conductive zinc oxide powder of Comparative Example 6, no peak derived from the solid solution of nitrogen was observed. Table 1 shows the specific surface area of the conductive zinc oxide powder of Comparative Example 6, the solid solution ratio of aluminum, the solid solution ratio of nitrogen, and the volume resistivity immediately after manufacture, after 30 days and after 210 days. The specific surface area of the conductive zinc oxide powder of Comparative Example 6 was 3.17 m ² / g, the aluminum solid solution ratio was 0 mass%, and the nitrogen solid solution ratio was 0.060 mass%. Moreover, its volume resistivity is as high as 424.0 Ω · cm even immediately after production, and becomes higher as it exceeds the measurement limit (1 × 10 ⁸ Ω · cm) of the measuring device after 30 days and after 210 days. It was confirmed that the time-dependent change occurred.

  Further, the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 6 was measured to examine the presence or absence of lattice vacancies (oxygen vacancies). The fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 6 was measured in the same manner as in Example 1. The results are shown in FIG. 14 together with the fluorescence spectra of the conductive zinc oxide powders of Example 1 and Comparative Examples 3, 4, and 5. In the fluorescence spectrum of the conductive zinc oxide powder of Example 1, no peak is observed in the vicinity of 500 nm, whereas in the fluorescence spectrum of the conductive zinc oxide powder of Comparative Example 6, it is 500 nm as in the other comparative examples. A peak was observed in the vicinity. The conductive zinc oxide powder of Comparative Example 6 exhibits conductivity with a high volume resistivity immediately after production, and the change over time is significant because the conductivity of the conductive zinc oxide powder of Comparative Example 6 is lattice empty. This is presumed to be due to pores (oxygen deficiency).

(Comparative Example 7)
The mixed powder was fired by the same method as in Comparative Example 3 except that the atmosphere during firing of the mixed powder was an ammonia (NH ₃ ) atmosphere. However, no fired product remained in the crucible after firing. It is considered that because the zinc oxide powder was heated in an ammonia atmosphere, zinc oxide was reduced to generate zinc, and the generated zinc was heated to a temperature equal to or higher than its boiling point and evaporated.

As described above, for the production of the conductive zinc oxide powder, the Al ₂ (NH) ₃ powder, which is a kind of the Al—N—H compound powder of the present invention, is used as the aluminum source, so that the pulverization after firing is performed. However, a practical conductive zinc oxide powder having a low volume resistivity and little change over time could be produced by a simple method in which raw materials were mixed and fired at a specific temperature range. The conductive zinc oxide powder was a novel conductive zinc oxide powder in which both aluminum and nitrogen were dissolved. On the other hand, using conventional aluminum sources such as aluminum sulfate, aluminum nitrate, and aluminum chloride, using aluminum nitride containing both aluminum and nitrogen, or using a conventional aluminum source, firing in an ammonia atmosphere. However, the method of simply mixing and firing the raw materials could not provide a conductive zinc oxide powder having a low volume resistivity and little change over time, in which both aluminum and nitrogen are in solid solution.

Claims (9)

  Conductivity characterized in that zinc oxide powder and Al—N—H compound powder containing imide group and / or amide group are mixed and fired in an inert atmosphere in the range of 900 ° C. to 1200 ° C. A method for producing zinc oxide powder.   The zinc oxide powder is mixed with the Al—N—H-based compound powder containing the imide group and / or amide group in a proportion of 0.5 mol% to 10 mol% in terms of aluminum with respect to the zinc oxide powder. The method for producing a conductive zinc oxide powder according to claim 1.   Mixing the zinc oxide powder and the Al—N—H-based compound powder containing the imide group and / or amide group in a ratio of 2 mol% to 10 mol% in terms of aluminum with respect to the zinc oxide powder. The method for producing a conductive zinc oxide powder according to claim 1.   The carbon impurity concentration of the Al-N-H-based compound powder containing the imide group and / or amide group is 2% or less on a mass basis, and the conductivity according to any one of claims 1 to 3. Method for producing zinc oxide powder.   A conductive zinc oxide powder characterized by solid solution of aluminum and nitrogen.   6. The conductive zinc oxide powder according to claim 5, wherein aluminum is solid-dissolved in a proportion of 0.01% by mass to 1.00% by mass with respect to zinc oxide.   The conductive zinc oxide powder according to claim 5 or 6, wherein nitrogen is solid-dissolved in a proportion of 0.02 mass% to 0.40 mass% with respect to zinc oxide.   Aluminum is solid-dissolved in a proportion of 0.3% to 1.00% by mass with respect to zinc oxide, and nitrogen is solid-dissolved in a proportion of 0.1% to 0.40% by mass with respect to zinc oxide. The conductive zinc oxide powder according to claim 5, wherein the conductive zinc oxide powder is formed. A specific surface area of 3.00m ² /g~5.00m ² / g, conductive zinc oxide according to claim 5-8 any one, wherein the volume resistivity of not more than 100 [Omega · cm Powder.

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