KR20090095492A - Method for producing perovskite-typed barium titanate powder - Google Patents

Abstract

Provided is a method for manufacturing perovskite barium titanate powder used as a functional ceramic material for electronic components. A method for manufacturing perovskite barium titanate powder used as a functional ceramic material for electronic components comprises the following step of calcining an organic acid salt composite containing Ba and Ti in the presence of humid air. The calcination is performed when the humid air is introduced to a furnace. The humid air is prepared by adjusting the temperature of water. The dew point of the humid air is 15 °C or greater. The calcination is performed at the temperature of 700 - 1200 °C.

Description

Manufacturing method of perovskite type barium titanate powder {METHOD FOR PRODUCING PEROVSKITE-TYPED BARIUM TITANATE POWDER}

The present invention relates to a method for producing perovskite-type barium titanate powder, and more particularly, to a method for producing perovskite-type barium titanate powder useful as a raw material for functional ceramics such as piezoelectric materials, optical electronic materials, dielectrics, semiconductors and sensors. .

Perovskite-type barium titanate powder has conventionally been used as a raw material for functional ceramics such as piezoelectric bodies and multilayer ceramic capacitors. However, in recent years, multilayer ceramic capacitors have been required to increase the number of laminated layers and increase the high dielectric constant in order to increase their capacity, and therefore, it is desired to have fine tetragonal tetragons for perovskite-type barium titanate powders.

As one method for producing the perovskite type barium titanate powder, there is a method for calcining a complex organic acid salt containing Ba atoms and Ti atoms. For example, an oxalate method is performed in which a solution containing barium chloride and titanium chloride is brought into contact with an aqueous solution of oxalic acid to react to obtain barium titanyl oxalate, followed by calcination of the barium titanyl oxalate followed by oxalic acid treatment. The perovskite-type barium titanate powder obtained by this oxalate method has a problem that it is difficult to obtain fine and high tetragonality.

For this reason, for example, Patent Document 1 below discloses fine barium titanyl oxalate (BaTiO (C ₂ O ₄₎ obtained by simultaneously mixing a water-soluble barium salt, a water-soluble titanium salt, and an aqueous solution of oxalic acid, and then stirring and stirring the obtained gel in a short time. ), it has been suggested how to calcination at 700 to 900 ℃ the crystal of 4H ₂ O).

Further, Patent Documents 2 and 3 below propose methods of calcining barium oxalate titanyl obtained after wet grinding of barium oxalate titanate to obtain fine barium titanate.

In addition, Patent Document 4 discloses a mixed solution of an aqueous barium chloride solution and an aqueous titanium chloride solution to an oxalic acid solution to precipitate barium titanate, followed by aging, washing, filtration and drying to produce barium titanate. ; Calcining the prepared barium titanate oxalite first, and then pulverizing to produce fine barium titanate powder; And after the second calcination of the fine barium titanate powder, a second grinding step has been proposed.

[Patent Document 1] Japanese Unexamined Patent Publication No. 61-146710

[Patent Document 2] Japanese Patent Application Laid-Open No. 2004-123431

[Patent Document 3] Japanese Unexamined Patent Publication No. 2002-53320

[Patent Document 4] Japanese Patent Application Laid-Open No. 2003-212543

Although various methods for producing a perovskite-type barium titanate powder using a complex organic acid salt have been studied as in the conventional art, perovskite-type barium titanate powder having fine and high tetragonality by a more industrially advantageous method. There was a need for a method for producing the same.

It is therefore an object of the present invention to provide a method for producing perovskite-type barium titanate powder which is fine by an industrially advantageous method using a composite organic acid salt and which has high tetragonality even at the same calcination temperature.

The present inventors have made intensive studies in view of the above situation, and as a result, when a large amount of carbonic acid gas is present in the furnace when calcining a complex organic acid salt containing Ba atoms and Ti atoms, it is applicable to the perovskite-type barium titanate powder obtained. Since barium carbonate is formed on the surface or inside of the powder, a perovskite-type barium titanate powder having low characteristics as a ferroelectric, having a lower ratio (c / a) of the c-axis and a-axis, which are indicative of tetragonal crystals, is also produced. When generation of carbonate gas during calcination is suppressed, perovskite-type barium titanate powder having high tetragonality can be produced even at the same calcination temperature, and further, when calcination is performed in the presence of humidified air, the carbon dioxide gas is humidified. It is effectively absorbed by the water vapor in the air, which can reduce the concentration of carbon dioxide gas in the calcining, Fine probe Perovskite - Type of barium titanate powder, and have found that a high spinning stability at the same calcination temperature, and completed the present invention.

That is, the method for producing the perovskite-type barium titanate powder to be provided by the present invention, in the method for producing a perovskite-type barium titanate powder by calcining a complex organic acid salt containing a Ba atom and a Ti atom, It is characterized in that in the presence of humidified air.

According to the present invention, it is possible to produce perovskite-type barium titanate powder which is fine by an industrially advantageous method and has high tetragonality even at the same calcination temperature. The manufactured perovskite-type barium titanate powder is particularly useful as a raw material for functional ceramics for electronic components such as piezoelectric materials, optical electronic materials, dielectrics, semiconductors, and sensors.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on preferable embodiment.

The method for producing a perovskite-type barium titanate powder according to the present invention is a method for producing a perovskite-type barium titanate powder by calcining a complex organic acid salt containing a Ba atom and a Ti atom, wherein the calcination is performed by humidifying air. It is characterized by performing in presence.

The complex organic acid salt (hereinafter abbreviated as "complex organic acid salt") containing Ba atoms and Ti atoms of the raw material used in the present invention can be used without particular limitation as long as it can form double salts of Ba and Ti. . Examples of such complex organic acid salts include carboxylates such as formate, oxalate, acetate, propionate, succinate, malate, tartarate, citrate and lactate or two or more of these carboxylic acids. For example, the compound salt of carboxylic acid containing both oxalic acid and lactic acid (refer Japanese patent application 2007-40018) etc. are mentioned. For example, barium titanyl oxalate, barium titanyl citrate, barium titanyl succinate, etc. are mentioned.

Among these, in the present invention, oxalate and citrate are preferable, and particularly, the oxalate can be easily produced in which the atomic ratio of Ba / Ti is around 1, and is particularly preferable in view of production cost.

The content ratio of Ba atom and Ti atom in the complex organic acid salt is a molar ratio (Ba / Ti) of Ba atom and Ti atom, and is 0.99 to 1.01, preferably 0.995 to 1.005. It is especially preferable at the point of manufacture.

In addition, in the present invention, the complex organic acid salt may contain Ca or / and Sr atoms as a partial replacement of Ba atoms, which are A site elements in the case of perovskite type barium titanate powder, and are B site elements. Zr atoms may be contained as part of the Ti atoms. In this case, the substitution amount of Ca or / and Sr atoms to be partially replaced by Ba is not particularly limited, but is preferably less than 50 mol% with respect to Ba atoms. On the other hand, the amount of substitution of Zr atoms which is partially substituted for Ti is not particularly limited, but is preferably less than 50 mol% with respect to Ti atoms. The mixing ratio of Ti and Zr (B site element) to Ba and Ca and / or Sr (A site element) is 0.99 to 1.01, preferably 0.995 to 1.005 in molar ratio (A site element / B site element). desirable.

Although the other physical properties of the complex organic acid salt used in the present invention are not particularly limited, the average particle diameter obtained by scanning electron micrograph (SEM observation) is 200 µm or less, preferably 100 µm or less, which is fine and has high tetragonality. It is preferable at the point which manufactures a perovskite type barium titanate. In addition, the average particle diameter calculated | required from the said scanning electron micrograph (SEM observation) shows the value of the average calculated | required from the scanning electron microscope observation (SEM observation) with respect to 1000 samples extracted arbitrarily.

The complex organic acid salt used in the present invention can be produced by a known method. For example, in the case of oxalate, an aqueous solution containing titanium chloride and barium chloride and an oxalic acid aqueous solution are brought into contact with each other to precipitate the oxalate, and if necessary, a aging reaction is carried out, followed by solid-liquid separation and recovery by a conventional method. It can manufacture by wash | cleaning, drying, grinding | pulverization, etc. accordingly. For example, by the methods described in Japanese Patent Laid-Open No. 2006-321722, Japanese Patent Laid-Open No. 2006-321723, Japanese Patent Laid-Open No. 2006-348026, Japanese Patent Laid-Open No. 2004-123431, etc. The complex organic acid salt manufactured is mentioned.

In the case of citrate, a solution of barium chloride is added to a citric acid solution of titanium, the citrate salt is precipitated, and a aging reaction is carried out if necessary, followed by solid-liquid separation and recovery by conventional methods, and washing and drying as necessary. And pulverization can be produced. For example, the complex organic acid salt manufactured by the method described in US Pat. No. 3,231,328 can be mentioned.

Further, a complex salt of carboxylic acid containing both oxalic acid and lactic acid can be prepared by contacting a solution containing a titanium component, a barium component and a lactic acid component with a solution containing an oxalic acid component in contact with a solvent containing an alcohol. (See Japanese Patent Application No. 2007-40018).

Moreover, when grind | pulverizing a complex organic acid salt, it is preferable to carry out by wet, for example, the method of charging the slurry containing the said complex organic acid salt into a wet grinding device and grind | pulverizing is mentioned. As a wet grinding apparatus, a ball mill, a bead mill, etc. are mentioned, for example. As a solvent used for the preparation of the slurry, one which is inert to a complex organic acid salt is used. For example, water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, dimethylformamide And diethyl ether. Among these, when organic solvents such as methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, dimethylformamide, and diethyl ether are used, and those having low elution of Ba and Ti are used, It is preferable because a high perovskite type barium titanate powder can be obtained. The said solvent can be used 1 type or in combination of 2 or more types. In addition, after a wet process, drying can also be performed for every slurry with a spray dryer.

In addition, the composite organic acid salt is preferably used in the high purity to obtain a high purity perovskite-type barium titanate powder.

The reaction operation of the present invention calcines the complex organic acid salt. Organics included in the final product are undesirable because they not only impair the dielectric properties of the material, but also cause instability in behavior in the thermal process for ceramicization. Therefore, in the present invention, it is necessary to thermally decompose the complex organic acid salt by calcination to obtain the target perovskite-type barium titanate powder and to sufficiently remove the organic substance derived from the complex organic acid salt.

The calcination temperature is 700 to 1200 ° C, preferably 800 to 1000 ° C. The reason for this is that if the calcination temperature is less than 700 ° C, the formation reaction to the perovskite-type barium titanate does not proceed, and thus it is easy to be in an unreacted state. It is not desirable because barium tends to cause grain growth.

The calcination time is at least 4 hours, preferably 6 to 30 hours. In addition, this calcination may be pulverized and recalcined once in order to make powder characteristics homogeneous. The firing furnace used for calcination can use a batch type or a continuous electric furnace and a gas furnace, As an example, a roller hearth kiln, a rotary kiln, a pusher furnace, etc. are mentioned. .

In the method for producing the perovskite-type barium titanate powder of the present invention, it is particularly important to perform the above calcination in the presence of humidified air in the atmosphere.

In specific operation, calcination can be performed while introducing humidified air into the firing furnace.

As the humidified air, air which has been passed through water adjusted to a temperature, humidified air, or air humidified by mixing water vapor with air can be used.

The moisture content in the humidified air is not particularly limited, but when humidified air having a dew point of 15 ° C. or higher, preferably 20 to 26 ° C., particularly preferably 21 to 25 ° C., the perovskite-type barium titanate is added. It is especially preferable at the point which efficiently absorbs the carbon dioxide gas which generate | occur | produced in the kiln in the production reaction.

1 is a graph showing a humidity chart and showing a relationship between the temperature (° C.) and the amount of saturated water vapor (humidity 100%) (g) contained in 1 m 2 of dry air. The relationship between the amount of saturated steam in FIG. 1 and temperature is shown in Table 1 below. In addition, the temperature (degreeC) of Table 1 shows a dew point.

2 is a graph for calculating the dew point from the humidity curve. Dew point can be calculated | required based on FIG. 2, curve Hs is a humidity curve of 100% humidity, and curve H1 is a humidity curve of arbitrary humidity a%. However, a represents the humidity of less than 100% humidity. Curve Hs is the same as the curve shown in FIG. Humidified air Ha of temperature t2 and humidity a% contains the steam of the amount of water vapor h2 in temperature t2 of curve H1. Therefore, in order to determine the dew point of the temperature t2 and the humidity a% humidified air A, the water vapor amount h2 is moved in the direction of the saturated water vapor curve Hs, and the temperature t1 at the intersection h1 between the water vapor amount h2 and the curve Hs is the dew point of the humidified air Ha. Becomes

The rate of introduction of humidified air into the kiln depends on the capacity of the kiln, for example, when using a kiln having a capacity of 3L, the perovskite is 1 L / min or more, preferably 2-5 L / min. It is preferable at the point which produces | generates the carbon dioxide gas which generate | occur | produced in the kiln in the formation reaction to a sky-type barium titanate efficiently, and prevents furnace temperature from falling by humidified humidified air. In addition, at the time of introduction of the humidified humidified air into the calcination furnace, the introduction of the humidified air into the calcination furnace at least before the pyrolysis of the complex organic acid salt effectively absorbs the carbon dioxide generated in the reaction process and suppresses the generation of the carbon dioxide gas. It is especially preferable in that it exists.

The perovskite-type barium titanate powder after calcination can be made into a product by, for example, washing with an acid solution if necessary, washing with water, drying, pulverizing and classifying. A drying method can use a conventional method and it is not specifically limited, When wet grinding is performed, the method of using a spray dryer can also be applied, for example.

The perovskite-type barium titanate powder obtained in the present invention has a high tetragonality with a ratio of c-to-a-axis (c / a) serving as an index of tetragonal, preferably 1.004 or more, preferably 1.006 to 1.010. In addition, preferable physical properties of the perovskite-type barium titanate powder obtained in the present invention have an average particle diameter of 0.5 µm or more, preferably 0.05 to 0.05, for 1000 samples arbitrarily extracted by scanning electron microscope observation. 0.3 µm, BET specific surface area of at least 2 m 2 / g, preferably 3 to 20 m 2 / g, very high purity, especially raw materials for functional ceramics for electronic components such as piezoelectrics, optical electronics, dielectrics, semiconductors, sensors, etc. Perovskite-type barium titanate powder useful as a powder.

If necessary, the perovskite-type ceramic raw material powder containing the oxide of the subcomponent element can be obtained by mixing the subcomponent element-containing compound with the complex organic acid salt and then calcining thereafter. In addition, the perovskite-type ceramic raw material powder containing the subcomponent element can also be obtained by adding the subcomponent element-containing compound to the perovskite-type barium titanate powder after calcination and again calcining. As the minor component elements, rare earth elements such as Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Li, Bi, Zn, Mn , Al, Si, Sr, Co, V, Nb, Ni, Cr, B, Fe and Mg is used as one or more elements selected from.

In addition, the combination and addition amount of these subcomponent element containing compounds can be arbitrarily set according to the dielectric properties required for the ceramic to be produced. The addition amount of a specific subcomponent element containing compound is 0.1-5 weight part normally as an element among subcomponent element containing compounds with respect to 100 weight part of perovskite type barium titanate powder. In addition, the said subcomponent element containing compound may be either an inorganic substance or an organic substance. For example, oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates and alkoxides containing the above elements may be mentioned. When a subcomponent element containing compound is a compound containing Si element, silica sol, sodium silicate, etc. can also be used in addition to the said oxide etc.

The perovskite-type barium titanate powder obtained in the present invention can be used as a raw material for producing a multilayer capacitor. For example, first, the perovskite-type barium titanate powder and conventionally known compounding agents such as additives, organic binders, plasticizers, and dispersants are mixed, dispersed and slurried, and solids in the slurry are molded to obtain ceramic sheets. . Subsequently, a conductive paste for forming internal electrodes is printed on one surface of the ceramic sheet, and after drying, a plurality of ceramic sheets are laminated, and then a laminate is formed by pressing in the thickness direction. Furthermore, this laminated body is heat-processed, a binder removal process is performed, and it bakes and produces a fired body. Then, a laminated capacitor can be obtained by apply | coating and baking In-Ga paste, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, etc. to this baking body.

In addition, the perovskite-type barium titanate powder obtained by this invention is mix | blended with resin, such as an epoxy resin, a polyester resin, a polyimide resin, and a printed wiring board and a multilayer printed wiring board as a resin sheet, a resin film, an adhesive agent, etc., for example. It can use suitably for materials, such as these. Further, the perovskite-type barium titanate powder is a dielectric material of an EL element, a common material for suppressing a shrinkage difference between an internal electrode and a dielectric layer, a base material of an electrode ceramic circuit board or a glass ceramic circuit board, a raw material of a circuit peripheral material, and exhaust. It can be used suitably as a catalyst used at the time of reaction, such as gas removal or chemical synthesis, the surface modifier of the printing toner which gives an antistatic effect or a cleaning effect.

<Example>

Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.

<Production of barium titanyl oxalate>

A mixed solution in which 600 g (2.456 mol) of barium chloride dihydrate salt and 444 g (2.342 mol) of titanium tetrachloride was dissolved in 4100 ml of water was prepared, and this solution was prepared as A solution. Subsequently, 620 g of oxalic acid was dissolved in 1500 ml of hot water at 70 ° C to prepare an aqueous oxalic acid solution, which was used as B solution. To solution A, solution B was added over 120 minutes while stirring at 70 ° C., and further aged at 70 ° C. for 1 hour under stirring. After cooling, it was filtered to recover barium titanyl oxalate. The recovered barium titanyl oxalate was then repulsed three times in 4.5 L of distilled water for washing. Then, drying at 105 ℃, and then pulverized, barium titanyl oxalate _{(C 2 O (BaTiO 4)} · 4H 2 O) 1000 g was obtained. The physical property values of the obtained barium titanyl oxalate are shown in Table 2 below.

In addition, Ba / Ti molar ratio was computed based on the value analyzed by fluorescence X-ray analysis. In addition, the average particle diameter was made into the average value calculated | required about 1000 samples arbitrarily extracted by the scanning electron microscope (SEM) photograph.

Examples 1-4

In a firing furnace including the electric batch furnace shown in FIG. 3, 7 g of the barium titanyl oxalate sample was heated to a temperature shown in Table 3 below at a temperature increase rate of 2.5 ° C./min under an atmosphere, and maintained for 6 hours to be calcined.

The inside of the slope of the furnace 1 of the kiln shown in FIG. 3 is covered with an alumina fiber board, and the sample 3 is accommodated in the barrel of the sample container 2 made of alumina in the furnace. Humidified air 6 is introduced into the furnace from the inlet 5, and humidified air is discharged out of the furnace from the outlet 8 of the discharge pipe 7.

At the same time as calcination commences, calcination was carried out while passing air through water heated to 30 ° C. and introducing humidified air A (dew point 21 ° C.) at a rate of 2 L / min. The capacity of the kiln is 3 liters.

In addition, the state of air before heating is 27.8 degreeC, humidity 24%, and dew point of 7 degreeC. The humidified air A humidified by letting it pass through the water heated at 30 degreeC, is 26.1 degreeC, 72% of humidity, and 21 degreeC of dew point by the measured value of the inlet (5).

After the completion of calcination, the mixture was cooled and pulverized to obtain barium titanate powder.

Examples 5-8

A dry powder was prepared in the same manner as in Example 1, and 7 g of the dry powder was heated in an electric batch furnace at a temperature increase rate of 2.5 ° C./min to the temperature shown in Table 3, and maintained for 6 hours to be calcined.

At the same time as calcination commences, calcination was carried out while passing air through water heated to 45 ° C. and introducing humidified air B (dew point 25 ° C.) at a rate of 2 L / min.

In addition, the state of air before heating is 27.8 degreeC, humidity 24%, and dew point of 7 degreeC. The humidified air B humidified by passing through water heated to 45 ° C is 27.1 ° C, humidity 87%, and dew point 25 ° C in the measured value at the inlet 5.

After the completion of calcination, the mixture was cooled and pulverized to obtain barium titanate powder.

Comparative Examples 1 to 4

A dry powder was prepared in the same manner as in Example 1, and 7 g of the dry powder was heated in an electric batch furnace at a temperature increase rate of 2.5 ° C./min to the temperature shown in Table 3, and maintained for 6 hours to be calcined.

Calcination was performed without introducing air into the kiln.

After the completion of calcination, the mixture was cooled and pulverized to obtain barium titanate powder.

Comparative Examples 5 to 8

A dry powder was prepared in the same manner as in Example 1, and 7 g of the dry powder was heated in an electric batch furnace at a temperature increase rate of 2.5 ° C./min to the temperature shown in Table 3, and maintained for 6 hours to be calcined. In addition, calcination was carried out while introducing carbonate gas into the baking furnace at the rate of 2 L / min at the same time as calcination start.

In addition, carbonic acid gas was used that does not heat. Carbonic acid gas which is not heated is 22.3 degreeC, 37% of humidity, and dew point of 8 degreeC by the measured value of the inlet port 5. As shown in FIG.

After the completion of calcination, the mixture was cooled and pulverized to obtain barium titanate powder.

Comparative Examples 9 to 12

A dry powder was prepared in the same manner as in Example 1, and 7 g of the dry powder was heated in an electric batch furnace at a temperature increase rate of 2.5 ° C./min to the temperature shown in Table 3, and maintained for 6 hours to be calcined.

In addition, calcination was performed while introducing air into the baking furnace at the rate of 2 L / min at the same time as calcination start.

In addition, the state of air is 27.8 degreeC, 24% of humidity, and dew point of 7 degreeC by the measured value of the inlet (5).

After the completion of calcination, the mixture was cooled and pulverized to obtain barium titanate powder.

Evaluation of physical properties of barium titanate sample

For the barium titanate samples obtained in Examples 1 to 8 and Comparative Examples 1 to 12, the ratio (c / a) between the c-axis and the a-axis serving as an index of the average particle diameter, the BET specific surface area, and the tetragonal crystal was measured. The results are shown in Table 4 below. In addition, the ratio of c-axis and a-axis was calculated | required by X-ray diffraction. In addition, the average particle diameter was made into the average value calculated | required about 1000 samples arbitrarily extracted by the scanning electron microscope (SEM) photograph.

(Note) In Comparative Example 5, since crystalline barium titanate was not produced, c / a could not be measured.

From Table 4, the barium titanate obtained by calcining by introducing humidified air is obtained by calcining without the introduction of humidifying air with the same calcining temperature, or the index of tetragonal c as compared with that of the comparative example having the same BET specific surface area. It can be seen that the ratio of the axis to the a axis (c / a) is high and the tetragonality is excellent.

Industrial availability

Since the present invention can produce fine and highly tetragonal perovskite-type barium titanate powder, the manufactured perovskite-type barium titanate powder is particularly suitable for piezoelectric, optical electronic materials, dielectrics, semiconductors, sensors and the like. It can use as a raw material of the functional ceramic for components.

1 is a graph showing the relationship between the temperature and the amount of saturated water vapor (humidity 100%) contained in 1 m 2 of dry air.

2 is a graph for obtaining a dew point from a humidity curve.

3 is a schematic view showing an embodiment of a firing furnace.

<Brief description of symbols for the main parts of the drawings>

1: as

2: sample container

3: sample

4: introduction tube

5: inlet

6: humidifying air

7: discharge pipe

8: outlet

9: plug

10: Foundation

Claims (7)

A method for producing a perovskite-type barium titanate powder by calcining a complex organic acid salt containing a Ba atom and a Ti atom, wherein the calcination is performed in the presence of humidified air. Method of making the powder. The method for producing a perovskite-type barium titanate powder according to claim 1, wherein the calcination is performed while introducing humidified air into the firing furnace. The method for producing perovskite-type barium titanate powder according to claim 1 or 2, wherein the humidified air is made of air humidified through water adjusted with temperature. The manufacturing method of the perovskite type barium titanate powder of any one of Claims 1-3 whose dew point of the said humidified air is 15 degreeC or more. The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 4, wherein the calcination is performed at 700 to 1200 ° C. The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 5, wherein the complex organic acid salt is a carboxylate. The method for producing a perovskite-type barium titanate powder according to any one of claims 1 to 5, wherein the complex organic acid salt is oxalate.

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