JPS6241177B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to a double oxide of divalent metal and titanium.
MTiO ₃ (M is a divalent metal excluding Ba and Sr.)
The present invention relates to a method for producing a titanate. More specifically, the present invention relates to a method for producing titanates that can variably control the dielectric properties, temperature properties, etc. of ceramic materials. [Prior Art] Barium titanate (BaTiO ₃ ) is well known as a high dielectric constant material for capacitors. In order to control the dielectric properties, temperature properties, etc. of this barium titanate, various additives are generally added. Examples of additives include calcium titanate (CaTiO ₃ ) and magnesium titanate (MgTiO ₃ ). Conventionally, additives are added in the form of oxides or various salts such as carbonates, nitrates, and hydroxides, which are added to the main components and mixed.
It was common to go through the steps of calcination, crushing, and firing. However, according to the conventional method, when microscopically observed in the obtained titanate, the divalent metal and titanium do not necessarily distribute or react uniformly, and it is difficult to stabilize its properties. It was hot. Furthermore, impurities are likely to be mixed in from the crushing device during crushing, resulting in a disadvantage that the properties as a dielectric material are deteriorated. Furthermore, there was a drawback that the amount of energy consumed in the crushing equipment, baking equipment exceeding 1000°C, etc. was extremely high. In recent years, electronic components have been required to be smaller and have more advanced characteristics, and the raw material powder used for them must therefore be fine particles with a more uniform composition and higher purity than ever before. I'm getting used to it.
Meanwhile, in manufacturing processes, there is an increasing interest in producing materials with as little energy as possible. [Purpose of the invention] The present invention solves the above-mentioned drawbacks, and provides a method for producing titanate with a uniform desired composition, high purity, fine particles, and low cost using less energy. The purpose is to provide a method. [Structure of the Invention] The feature of the first invention is that an alkali alkoxide, a titanium alkoxide, a salt of a divalent metal other than barium and strontium, and water are mixed and reacted to obtain a titanate. In particular, in this mixed reaction, for convenience of handling, an alkali alkoxide and a titanium alkoxide are first mixed and reacted to synthesize an alkali titanium composite alkoxide, and then this alkali titanium composite alkoxide is mixed with a salt of a divalent metal other than barium and strontium. After mixing and reacting, it is preferable to further add water for hydrolysis to obtain a titanate. Further, the second invention of the present application is characterized in that after an amorphous titanate is obtained by mixing and reacting an alkali alkoxide, a titanium alkoxide, a salt of a divalent metal other than barium and strontium with water, the amorphous titanate is The purpose is to heat titanate to obtain crystalline titanate. Similar to the first invention, for convenience of handling, this mixed reaction involves first mixing and reacting an alkali alkoxide and a titanium alkoxide to synthesize an alkali titanium composite alkoxide, and then removing this alkali titanium composite alkoxide from barium and strontium. After mixing and reacting with a salt of a valent metal, it is preferable to further add water for hydrolysis to obtain an amorphous titanate. In addition, in order to facilitate handling, the above-mentioned mixing reaction is preferably carried out at a temperature range of 0 to 100° C. for both the first invention and the second invention. Further, it is preferable to dissolve the alkali alkoxide and titanium alkoxide in an organic solvent, since this facilitates mixing and speeds up the reaction. Further, the alkali alkoxide is preferably one alkoxide selected from lithium alkoxide, sodium alkoxide, and potassium alkoxide. In addition, excluding the above barium and strontium,
Preferably, the valence metal is one metal selected from Ca, Mg, Cd, Pb, and Ni. Furthermore, the amorphous titanate in the second invention of the present application
The heating temperature is preferably selected from a temperature range of 600° C. or higher and lower than the decomposition start temperature of the titanate because crystalline titanate can be obtained efficiently. In this specification, "alkoxide" refers to a compound in which the hydrogen atom of the OH group of an alcohol is replaced with a metal atom, and "alkali alkoxide" refers to an alkoxide of an alkali metal. [Process Description] The titanate of the present invention can be obtained by mixing an alkali alkoxide, a titanium alkoxide, a salt of a divalent metal other than barium and strontium, and water, and reacting the mixture. First, alkali alkoxide and titanium alkoxide are mixed and reacted to synthesize alkali titanium composite alkoxide, and then this alkali titanium composite alkoxide is mixed and reacted with a salt of a divalent metal other than barium and strontium.
It can also be obtained by hydrolysis by adding water. The manufacturing process of the latter titanate will be explained in detail step by step. <Synthesis of alkali titanium composite alkoxide> Alkali alkoxide prepared by directly reacting an alkali metal and alcohol with commercially available titanium alkoxide Ti(OR) ₄ are mixed to a desired composition and reacted to form alkali titanium composite alkoxide. Synthesize. As the alkali metal, any one of Li, Na, and K is preferable in order to achieve the object of the present invention. Further, when preparing the above-mentioned alkali alkoxide, methanol, ethanol, propanol, butanol, etc. are preferable as the alcohol because they are easy to obtain or produce industrially. The type of alcohol used is largely related to the reactivity when producing the alkoxide, but when the produced alkoxide is used as a starting material for the present invention, the type of alkyl group in the alkoxide is not essentially important. In addition, the metals and alcohols that are the starting materials for the alkali alkoxides and titanium alkoxides have the characteristic that their purity can be increased by relatively easy physical or chemical methods, and they do not contain any unnecessary ions. Alkoxides synthesized using these as starting materials can easily reduce impurities to 0.1% or less without any particular purification. In order to further increase the purity of these alkoxides, solid alkoxides are recrystallized, and liquid alkoxides are subjected to distillation, etc. In addition, the mixing and reaction of the alkali alkoxide and titanium alkoxide are performed for convenience of mixing,
It is preferable to carry out the reaction in an organic solvent in order to accelerate the reaction. As this solvent, benzene, alcohol, hexane, etc. are suitable, but benzene is most suitable because of its high solubility. There is no problem with the reaction temperature as long as it is below the temperature at which the alkali alkoxide and titanium alkoxide decompose, but for convenience of handling, it is preferable that the upper limit temperature does not exceed 100°C, and the lower limit temperature does not require any particular cooling. Since there is no temperature, 0°C is sufficient. A particularly desirable temperature is 40-100°C. If the reaction temperature exceeds the boiling point of the solvent, the reaction can be carried out under pressure in a pressure vessel. <Hydrolysis> Next, the synthesized alkali titanium composite alkoxide and a salt of a divalent metal other than barium and strontium are mixed and reacted, and then water is added to perform hydrolysis. Divalent metals other than barium and strontium can achieve the object of the present invention,
Examples include Ca, Mg, Cd, Pb, and Ni. This salt form is preferred because chlorides, acetates, and oxalates are industrially easily available and inexpensive. This hydrolysis is carried out by adding decarboxylated distilled water to the reaction product of the alkali titanium complex alkoxide and the divalent metal salt. This addition produces a powdery precipitate. If this precipitate is separated from the hydrolysis solution by filtration, titanate is obtained. This hydrolysis can be carried out by directly adding water during dissolution, or by contacting it with a stream of steam blown out from a pressurized container. In addition, the reaction temperature for hydrolysis is preferably 0 to 100°C for convenience of handling when no pressure is applied.
℃, particularly preferably 25 to 100℃. In the case of applying pressure or contacting with water vapor flow,
A temperature of 100 to 400°C is appropriate. <Heating> According to the method of the present invention, titanate obtained by reaction is often obtained in an amorphous state, but crystalline titanate can be easily obtained by heating. The heating temperature for converting this amorphous titanate into crystalline titanate is 600°C or higher and below the decomposition starting temperature of titanate in order to improve the efficiency of transition to crystalline titanate. Although it is preferable that
It can also be obtained at lower temperatures or by vacuum heating. In this case, the heating atmosphere is neutral,
Either an oxidizing or reducing atmosphere may be used. <Form of titanate> In either case, when titanate is obtained directly by the above reaction or when titanate is obtained by heating, chemical analysis shows that the obtained titanate contains no impurities. It is a highly pure substance of 0.1% or less, and according to electron microscopy,
They are fine particles with a particle size of 0.01 to 0.1 μm. It can also be confirmed that the ratio of divalent metal atoms to titanium atoms is extremely close to the stoichiometric ratio. Furthermore, the heating temperature for crystallizing titanate is higher than that of conventional methods.
Since the firing temperature is lower than the firing temperature of 1000°C or higher, it is easy to loosen even if agglomerates are formed. [Effects of the Invention] As described above, according to the present invention, by mixing and reacting an alkali alkoxide, a titanium alkoxide, a salt of a divalent metal other than barium and strontium, and water, or with an alkali alkoxide. Mix and react with titanium alkoxide to synthesize alkali titanium composite alkoxide, mix and react this alkali titanium composite alkoxide with salts of divalent metals other than barium and strontium, and then add water to hydrolyze. As a result, it is possible to produce highly pure, fine-grained titanate with a uniform atomic ratio extremely close to the target, and titanate can be obtained at a lower reaction temperature than the conventional firing temperature of 1000°C or higher. It can be produced at a low cost using less energy, and since divalent metal salts are used as raw materials,
It has excellent effects such as being able to be manufactured using easily available and inexpensive raw materials. [Examples] Next, in order to show specific embodiments of the present invention, the present invention will be explained in more detail using Examples. However, the examples shown below are merely examples, and the technical scope of the present invention is not limited thereby. It's not something you do. <Example 1> High purity Na metal 23.0g and isopropanol 450g
ml was reacted to synthesize sodium isopropoxide. Commercially available titanium isopropoxide was added to this sodium isopropoxide at a ratio of Na:Ti=2:1 to form sodium titanium composite alkoxide Na ₂
[Ti(OR) ₆ ] was synthesized. 158.1 g of calcium acetate and 114.1 g of calcium oxalate were separately added to the sodium titanium composite alkoxide synthesized as above.
A reflux reaction was carried out at 80°C for 2 hours. Next, while refluxing, 270 ml of decarboxylated distilled water was added dropwise in small portions to cause hydrolysis, and a precipitate was formed in each reaction system. After separating the precipitates from the hydrolysis solution by filtration, the precipitates were incubated at 70°C for 20
Two types of powders were obtained after drying for several hours. The properties of the two types of powders obtained were examined by X-ray diffraction in their original state. In addition, two types of powder
The powder was heated at four different temperatures: 400, 600, 800, and 1000°C, and the structure of the powder after heating was confirmed by X-ray diffraction. The results of X-ray diffraction analysis are shown in the table. From this result, when calcium acetate is used as a divalent metal salt, it becomes amorphous when dried at 70°C, becomes anhydrous crystalline above 400°C, CaCO ₃ is observed after heating at 400°C, and when dried at 600°C After heating above, the target substance is
It was identified as _CaTiO3 . In addition, calcium oxalate used as a divalent metal salt becomes amorphous when dried at 70°C, becomes anhydrous crystal at temperatures above 400°C,
_CaCO3 is seen after heating at 400-800℃, 1000
After heating at ℃, the target substance, CaTiO ₃ , was identified. When the particle size of the obtained titanate powder was measured using an electron microscope, it was found to be fine particles of 0.01 to 0.1 μm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was Ca/Ti = 0.98 to 1.02. <Example 2> 〓〓〓〓
In the same manner as in Example 1, sodium titanium composite alkoxide Na ₂ [Ti(OR) ₆ ] was synthesized, 230.4 g of cadmium acetate was added to this composite alkoxide, and the mixture was refluxed and hydrolyzed in the same manner as in Example 1. , a precipitate was formed. After separating the precipitate from the hydrolysis solution by filtration, it was dried at 70°C for 20 hours to obtain a powder. The properties of the obtained powder were examined by X-ray diffraction in the same manner as in Example 1, and heated in the same manner as in Example 1.
The structure of the powder after heating was confirmed by X-ray diffraction. The results of X-ray diffraction analysis are shown in the table. From this result, the X-ray diffraction pattern after heating at 400°C or less was amorphous, and heating at 600°C turned into anhydrous crystals, and the target substance, CdTiO ₃ , was obtained after heating. Furthermore, when the particle size of the obtained titanate powder was measured using an electron microscope, it was found that the particle size was the same as in Example 1.
They were fine particles of 0.01 to 0.1 μm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was the same as in Example 1: Cd/Ti =
It was 0.98-1.02. <Example 3> In the same manner as in Example 1, sodium titanium composite alkoxide Na ₂ [Ti(OR) ₆ ] was synthesized, and 142.3 g of magnesium acetate and 112.3 g of magnesium oxalate were separately added to this composite alkoxide.
When each was subjected to reflux reaction and hydrolyzed in the same manner as in Example 1, a precipitate was formed in each case. After separating the precipitate from the hydrolysis solution by filtration, the temperature was 70°C.
After drying for 20 hours, two types of powder were obtained. The properties of the two types of powders obtained were examined by X-ray diffraction in the same manner as in Example 1, and they were heated in the same manner as in Example 1, and the structures of the powders after heating were confirmed by X-ray diffraction. . The results of X-ray diffraction analysis are shown in the table. From this result, the X-ray diffraction pattern using magnesium acetate as the divalent metal salt is amorphous after heating below 400°C, but becomes anhydrous crystal when heated above 600°C, and after heating, the X-ray diffraction pattern is amorphous. The substance MgTiO ₃ was obtained. In addition, those using magnesium oxalate as a divalent metal salt are amorphous when dried at 70℃, and dried at 400℃.
This resulted in anhydrous crystals, and after heating at 400-800°C, MgCO ₃ was observed, and after heating at 1000°C, it was identified as the target substance, MgTiO ₃ . Furthermore, when the particle size of the obtained titanate powder was measured using an electron microscope, it was found that the particle size was the same as in Example 1.
They were fine particles of 0.01 to 0.1 μm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was Mg/Ti = as in Example 1.
It was 0.98-1.02. <Example 4> In the same manner as in Example 1, sodium titanium composite alkoxide Na ₂ [Ti(OR) ₆ ] was synthesized, and 325.2 g of lead acetate and lead oxalate were added to this composite alkoxide.
295.2g and 278.1g of lead chloride were added separately, Example 1
When each was subjected to reflux reaction and hydrolyzed in the same manner as above, a precipitate was formed in each case. After separating the precipitate from the hydrolysis solution by filtration, it was dried at 70°C for 20 hours to obtain three types of powder. The properties of the three types of powder obtained were examined by X-ray diffraction in the same manner as in Example 1, and they were heated in the same manner as in Example 1, and the structures of the powders after heating were confirmed by X-ray diffraction. . The results of X-ray diffraction analysis are shown in the table. From this result, the X-ray diffraction patterns of all divalent metal salts using lead acetate, lead oxalate, and lead chloride after heating at 400°C or less are amorphous, and when heated at 600°C It became anhydrous crystals, and after heating, the target substance PbTiO ₃ was obtained. In addition, when the particle size of the obtained titanate powder was measured using an electron microscope, it was found that the particle size was the same as in Example 1.
They were fine particles of 0.01 to 0.1 μm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was Pb/Ti = Pb/Ti as in Example 1.
It was 0.98-1.02. <Example 5> In the same manner as in Example 1, sodium titanium composite alkoxide Na ₂ [Ti(OR) ₆ ] was synthesized, and 176.7 g of nickel acetate and 146.7 g of nickel oxalate were separately added to this composite alkoxide. Example 1
When each was subjected to reflux reaction and hydrolyzed in the same manner as above, a precipitate was formed in each case. After separating the precipitate from the hydrolyzed solution by filtration, it was dried at 70°C for 20 hours to obtain two types of powder. The properties of the two types of powders obtained were examined by X-ray diffraction in the same manner as in Example 1, and they were heated in the same manner as in Example 1, and the structures of the powders after heating were confirmed by X-ray diffraction. . 〓〓〓〓
The results of X-ray diffraction analysis are shown in the table. From this result, it was found that when nickel acetate and nickel acetate were used as divalent metal salts, they became amorphous when dried at 70°C.
It became anhydrous crystals above 400°C, NiO was observed after heating at 400-600°C, and it was identified as the target substance, NiTiO ₃ , after heating at 800°C. In addition, when the particle size of the obtained titanate powder was measured using an electron microscope, it was found that the particle size was the same as in Example 1.
They were fine particles of 0.01 to 0.1 μm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was Ni/Ti = as in Example 1.
It was 0.98-1.02.

[Table] 〓〓〓〓

Claims (1)

[Scope of Claims] 1. A method for producing a titanate by mixing and reacting an alkali alkoxide, a titanium alkoxide, a salt of a divalent metal other than barium and strontium, and water to obtain a titanate. 2. The method for producing a titanate according to claim 1, wherein the mixing reaction is carried out at a temperature range of 0 to 100°C. 3. The mixed reaction consists of a synthesis step in which alkali alkoxide and titanium alkoxide are mixed and reacted to synthesize alkali titanium composite alkoxide, and alkali titanium composite alkoxide synthesized in this synthesis step and salts of divalent metals other than barium and strontium. 3. The method for producing a titanate according to claim 1 or 2, comprising a hydrolysis step of mixing and reacting and then adding water and hydrolyzing to obtain a titanate. 4. The method for producing a titanate according to claim 3, wherein the reaction in the synthesis step is carried out in a state where the alkali alkoxide and titanium alkoxide are dissolved in an organic solvent. 5. The method for producing a titanate according to any one of claims 1 to 4, wherein the alkali alkoxide is one alkoxide selected from lithium alkoxide, sodium alkoxide, and potassium alkoxide. 6 Divalent metals other than barium and strontium are 1 selected from Ca, Mg, Cd, Pb, and Ni.
Claims 1 to 5 which are two metals
A method for producing a titanate according to any one of paragraphs. 7. Mix and react alkali alkoxide, titanium alkoxide, salts of divalent metals excluding barium and strontium, and water to obtain amorphous titanate, and then heat this amorphous titanate to crystallize it. A method for producing titanate to obtain quality titanate. 8. The method for producing a titanate according to claim 7, wherein the heating is performed at a temperature range of 600° C. or higher and lower than the decomposition start temperature of the titanate. 9 Mixed reaction is a synthesis step in which alkali alkoxide and titanium alkoxide are mixed and reacted to synthesize alkali titanium composite alkoxide, and alkali titanium composite alkoxide synthesized in this synthesis step and salts of divalent metals other than barium and strontium. After mixing and reacting, water is added and hydrolyzed to obtain an amorphous titanate, and the amorphous titanate is heated to form a crystalline titanate.
9. The method for producing a titanate according to claim 7 or 8, comprising a heating step to obtain a titanate.