KR102006539B1 - Synthesis method of nano-sized barium titanate powders by microwave heat-treatment - Google Patents

Abstract

The present invention provides a method for producing barium titanate nanopowder using a solid phase synthesis method, comprising: a) preparing a raw material powder of barium (Ba) and titanium (Ti); B) mixing the raw material powder prepared in step a) to form a mixture; C) preparing the mixture formed in the step b) into a shaped body; And d) step of microwave heat-treating the molded product prepared in step c).

Description

Method for producing barium titanate nanopowder using microwave heat treatment method {SYNTHESIS METHOD OF NANO-SIZED BARIUM TITANATE POWDERS BY MICROWAVE HEAT-TREATMENT}

The present invention relates to a production method of barium titanate (BaTiO ₃₎ nano powder through the solid-phase synthesis, to a barium titanate (BaTiO ₃₎ prepared nano-powder method using a microwave heat treatment method.

In the case of the solid phase reaction method, which is most used in the existing powder manufacturing process, the process is very simple, but the powders produced by the high temperature process have a large particle size, a wide particle size distribution, and irregular particle shapes. In the case of the sol-gel method, it is possible to atomize the powder because a low temperature process is possible, but a complicated sol manufacturing process of the raw powders is required. In the case of the hydrothermal synthesis method developed as a complementary measure, the powder atomization and the simplicity of the process have advantages, but the limited upper limit temperature by the Teflon reaction vessel and the agglomeration of the powder by the liquid phase reaction have a big disadvantage.

In this regard, the method for producing barium titanate powder and barium titanate powder through high temperature synthesis method in Korean Patent Laid-Open No. 10-2012-0060542, a mixture of titanium dioxide powder and barium carbonate powder is performed in a range of 650 to 850 ° C. A method of preparing a powder of barium titanate through a heat treatment process has been disclosed.

On the other hand, advantages such as high power density, high penetration depth and uniform reaction of microwave are very high in energy efficiency because microwave energy by electromagnetic field is directly transferred to the material during the synthesis process. This has a possible advantage. Accordingly, the present applicant has devised a method for producing a barium titanate (BaTiO ₃ ) nano-powder incorporating a microwave heat treatment process of the conventional solid-phase synthesis method.

Korean Patent Publication No. 10-2012-0060542

It is an object of the present invention to provide a method for preparing barium titanate (BaTiO ₃ ) nanopowders which can be processed at a low temperature by using a solid phase synthesis method and have a short process time.

A method of preparing barium titanate (BaTiO ₃ ) nanopowder using the solid phase synthesis method according to an embodiment of the present invention comprises the steps of a) preparing a raw material powder of barium (Ba) and titanium (Ti); B) mixing the raw material powder prepared in step a) to form a mixture; C) preparing the mixture formed in the step b) into a shaped body; And d) step of microwave heat-treating the molded product prepared in step c).

In addition, the step d) may use a microwave having a frequency range of 2.0 to 2.5 GHz.

In addition, the step d) may be performed the heat treatment in a temperature range of 100 to 800 ℃.

In addition, step d) may be performed for the heat treatment for 1 to 120 minutes.

In addition, step d) may be carried out the heat treatment at a temperature increase rate of 5 to 120 ℃ / min.

In addition, the first raw material powder prepared in step a) may include one or more of Ba (OH) ₂ , Ba (OH) ₂ H ₂ O, Ba (OH) ₂ 8H ₂ O, and BaCO ₃ .

In addition, the second raw material powder prepared in step a) may include one or more of rutile-TiO ₂ and TiO ₂ xH ₂ O.

In addition, in step b), the initial source of barium and the raw material powder of titanium may be mixed in a 1: 1 mol% ratio.

In addition, in step b), the mixing time of the raw material powder may be 1 to 30 minutes.

In addition, the step c) is the pressure applied to the mixture is 200 to 800 Kg / cm ² Lt; / RTI >

Production method of barium titanate (BaTiO ₃₎ nanopowder according to an embodiment of the present invention to take advantage of the heat treatment process using microwaves to produce a nanopowder of relatively barium titanate (BaTiO ₃₎ at a temperature lower than the conventional solid-phase synthetic method There is an advantage to this.

In addition, the method for producing barium titanate (BaTiO ₃ ) nano powder according to an embodiment of the present invention by adjusting the type and process parameters of the barium and titanium raw powder to maximize the reactivity of the microwave barium titanate (BaTiO ₃₎ in a short time There is an advantage that can be prepared for the nano powder.

1 is a step diagram of a method for preparing barium titanate (BaTiO ₃ ) nanopowder according to an embodiment of the present invention.
2 to 6 are X-ray diffraction graphs of barium titanate (BaTiO ₃ ) according to an embodiment of the present invention.
7 is a graph showing a change in crystal size of barium titanate (BaTiO ₃ ) according to an embodiment of the present invention.
8 and 9 are graphs showing changes in phase fraction of barium titanate (BaTiO ₃ ) according to an exemplary embodiment of the present invention.
10 and 11 are X-ray diffraction graphs according to an embodiment of the present invention.
12 is a high resolution scanning microscope photograph of barium titanate (BaTiO ₃ ) nanopowder according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the exemplary embodiments. Like reference numerals in the drawings denote members that perform substantially the same function.

The objects and effects of the present invention can be understood or clarified naturally by the following description, and the purpose and effect of the present invention are not limited by the following description. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a step diagram of a method for preparing barium titanate (BaTiO ₃ ) nanopowder according to an embodiment of the present invention. Referring to FIG. 1, the method for preparing barium titanate (BaTiO ₃ ) nanopowder includes a) step S1 of preparing a raw material powder of barium (Ba) and titanium (Ti); a) mixing the raw material powder prepared in step S1 to form a mixture b) S3; b) step S) of preparing a mixture formed in step S3 into a shaped body (S5); And c) d) step S7 of microwave heat treatment of the molded product prepared in step S5.

Hereinafter, a method for preparing barium titanate (BaTiO ₃ ) nanopowder using the microwave heat treatment method of the present invention will be described in detail for each step.

In step a) S1, first and second raw material powders may be prepared. a) In step S1, two sources of barium (Ba) and titanium (Ti) may be prepared, constituting barium titanate (BaTiO ₃ ). a) The first raw material powder of barium prepared in step S1 may include Ba (OH) ₂ 8H ₂ O (BH8) or the like. In addition, the first raw material powder of titanium prepared in step a) (S1) may include TiO ₂ xH ₂ O (TH).

The above-mentioned first and second raw material powders may have different reactivity with microwaves depending on the kind. In particular, in the case of the raw material powder to which the hydroxide (H ₂ O) is bonded, it may exhibit high reactivity by being affected by the electromagnetic field generated by the microwave due to the polarity of the hydroxide.

In one embodiment of the titanium raw material powder, in the case of TiO ₂ xH ₂ O, TiO (OH) ₂ gel is formed in a state in which a pH of 9 is maintained by reacting ammonia water with a mixed solution of TiCl ₄ and tertiary distilled water. In order to remove chlorine (Cl) ions, the mixture was washed with a mixture of tertiary distilled water and ethanol, dried and pulverized to prepare a powder.

b) step (S3) may be defined as a mixture forming step. b) step (S3) may be mixed with the raw material powder of the material prepared in step a) (S1). b) In step S3, conditions such as mixing ratio and mixing time may be controlled so that the raw material powder of barium and the raw material powder of titanium are easily mixed.

In an embodiment, b) step S3 may control a mixing ratio of the raw material powder of barium and the raw material powder of titanium to 1: 1 mol%. If the mixing ratio is not 1: 1, the stoichiometric ratio may be changed, which may cause a problem of producing an excessive second phase of barium or titanium. Accordingly, the raw material powders of barium and titanium were mixed at a ratio of 1: 1 mol% to BCTO (BC + TO), BCTH (BC + TH), BH8TO (BH8 + TO), BH8TH (BH8 + TH), and BH1TH. Mixed raw materials such as (BH1 + TH) and BH0TH (BH0 + TH) can be prepared.

In another embodiment, step b) S3 may control the mixing time of the first and second raw material powders from 1 to 30 minutes. If the mixing time is 30 minutes or more, due to the high reactivity of the first raw material powders such as BH8, BH1, BH0 exposed in the air, it is possible to produce a barium carbonate (BaCO ₃ ) phase during the mixing process. Accordingly, the problem can be prevented by controlling the mixing time of the material within 30 minutes to reduce the exposure time to the air.

c) in step S5, a molded product may be manufactured. c) step (S5) may be compression molding the mixture formed in step b) (S3). Through this, the contact area of the barium and titanium is increased to improve the reactivity of the heat treatment.

However, sintering may occur in the heat treatment step to be described later when applying a pressure of 600 kg / cm ² or more to the mixture during molding. Accordingly, in step c) (S5) it is possible to prevent the sintering by applying a pressure of 200 to 600 kg / cm ² to the mixture.

In step d) S7, a heat treatment process through microwaves may be performed. d) The microwave heat treatment process performed in step (S7) may be carried out at a lower process temperature than the general electrical heat treatment process. In addition, it is possible to shorten the manufacturing time of the barium titanate (BaTiO ₃ ) nanopowder through the microwave heat treatment process performed in step d) (S7).

In an embodiment, step d) S7 may use microwaves having a frequency range of 2.0 to 2.5 GHz. At this time, step d) (S7) may use a microwave heat treatment furnace operating at a power of 1.5 to 2.5 kW.

In addition, step d) (S7) may be carried out a heat treatment at a temperature of 100 to 800 ℃. d) step S7 may be subjected to a heat treatment in the range of 1 to 120 minutes. In addition, heat treatment may be performed for several seconds to several tens of seconds within a range of 1 minute. When the heat treatment is performed in the above temperature and time range, step d) (S7) may be carried out by setting the temperature increase rate of 1 to 120 ℃ / min.

Hereinafter, the present invention will be described in more detail by the following examples, comparative examples and experimental examples.

However, the following Examples, Comparative Examples, and Experimental Examples illustrate the present invention, but are not limited by the following examples.

< Example 1 >

<Example 1> was performed to determine the effect of the type of the first raw material powder and the second raw material powder to the production of barium titanate (BaTiO ₃ ) nanopowder. Ba (OH) ₂ 8H ₂ O (BH 8) was used as the first raw material powder. As the second raw material powder, TiO ₂ xH ₂ O (TH) was used. The first and second raw material powders were mixed using a stirrer. The mixed mixture was molded by applying a pressure of 600 kg / cm ² . The prepared molded article was subjected to a microwave heat treatment process. The microwave heat treatment was performed at 300 ° C. for 60 minutes at a temperature rising rate of 50 ° C./min. In addition, the microwave used a microwave heat treatment furnace operated at a frequency of 2.45 GHz and a power of 2 kW.

< Example 2 >

In Example 2, the second raw material powder used in <Example 1> was replaced with rutile-TiO ₂ (TO), and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 3 >

In Example 3, the first raw material powder used in <Example 1> was replaced with BaCO ₃ (BC), and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowder.

< Example 4 >

In Example 4, the first raw material powder used in <Example 1> was replaced with BaCO ₃ (BC) and the second raw material powder was replaced with rutile-TiO ₂ (TO), and other conditions were controlled in the same manner. Barium (BaTiO ₃ ) nano powders were prepared.

In addition, in order to determine the effect of the heat treatment temperature on the powder synthesis, barium titanate (BaTiO ₃ ) nano-powder was prepared by varying the heat treatment temperature.

< Example 5 >

In Example 5, the heat treatment temperature was changed to 100 ° C. in Example 1, and the other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 6 >

In Example 6, the heat treatment temperature was changed to 600 ° C. in Example 1, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

On the other hand, in order to determine the effect of the heat treatment method on the powder synthesis, the barium titanate (BaTiO ₃ ) nano-powder was prepared by changing the heat treatment method.

< Comparative Example 1 >

In <Comparative Example 1>, the heat treatment method in <Example 1> was replaced with a heat treatment method using general electricity, and the temperature increase rate was changed to 5 ° C / min. Other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowder.

< Comparative Example 2 >

In Comparative Example 2, the heat treatment temperature was changed to 600 ° C. in Comparative Example 1, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Comparative Example 3 >

In Comparative Example 3, the heat treatment temperature was changed to 800 ° C. in Comparative Example 1, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

In addition, d) a heat treatment time of this step by varying the heat treatment time, to examine the effects on synthesis of barium titanate (BaTiO ₃₎ was carried out to manufacture nano-powder of barium titanate (BaTiO ₃₎ nano powder.

< Example 7 >

In Example 7, the heat treatment temperature was changed to 100 ° C., the heat treatment time was maintained for 60 minutes, and the other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowder.

< Example 8 >

In Example 8, the heat treatment time of Example 7 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 9 >

In Example 9, the heat treatment time was changed to 30 minutes in Example 7, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

In addition, when the first raw material powder is Ba (OH) ₂ H ₂ O (BH1) In order to determine the effect of microwave heat treatment temperature on the production of barium titanate (BaTiO ₃ ) nanopowder, barium titanate by varying the microwave heat treatment temperature (BaTiO ₃ ) nano powder preparation was performed.

< Example 10 >

Ba (OH) ₂ H ₂ O (BH 1) was used as a first raw material powder of <Example 10>. As the second raw material powder, TiO ₂ xH ₂ O (TH) was used. The first and second raw material powders were mixed using a stirrer. The mixed mixture was molded by applying a pressure of 600 kg / cm ² . The prepared molded article was subjected to a microwave heat treatment process. The microwave heat treatment proceeded within 100 minutes at 100 ° C. at an elevated rate of 100 ° C./min. In addition, the microwave used a microwave heat treatment furnace operated at a frequency of 2.45 GHz and a power of 2 kW.

< Example 11 >

In Example 11, the heat treatment temperature was changed to 300 ° C. in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 12 >

In Example 12, the heat treatment temperature was changed to 600 ° C. in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

In addition, the a first material powder is Ba (OH) ₂ if (BH0) microwave heat treatment temperature of barium titanate (BaTiO ₃₎ In order to examine the effects of the production of nano-powders, and barium titanate, unlike a microwave heat-treating temperature (BaTiO ₃ ) Nano powder preparation was carried out.

< Example 13 >

Ba (OH) ₂ (BH0) was used as a first raw material powder of <Example 13>. As the second raw material powder, TiO ₂ xH ₂ O (TH) was used. The first and second raw material powders were mixed using a stirrer. The mixed mixture was molded by applying a pressure of 600 kg / cm ² . The prepared molded article was subjected to a microwave heat treatment process. The microwave heat treatment proceeded within 100 minutes at 100 ° C. at an elevated rate of 100 ° C./min. In addition, the microwave used a microwave heat treatment furnace operated at a frequency of 2.45 GHz and a power of 2 kW.

< Example 14 >

In Example 14, the heat treatment temperature was changed to 300 ° C. in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 15 >

In Example 15, the heat treatment temperature was changed to 600 ° C. in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

In addition, when the first raw material powder is Ba (OH) ₂ 8H ₂ O (BH8) in order to determine the effect of microwave heat treatment temperature on the production of barium titanate (BaTiO ₃ ) nanopowder, barium titanate by varying the microwave heat treatment temperature (BaTiO ₃ ) nano powder preparation was performed.

< Example 16 >

Ba (OH) ₂ 8H ₂ O (BH 8) was used as a first raw material powder of <Example 16>. As the second raw material powder, TiO ₂ xH ₂ O (TH) was used. The first and second raw material powders were mixed using a stirrer. The mixed mixture was molded by applying a pressure of 600 kg / cm ² . The prepared molded article was subjected to a microwave heat treatment process. The microwave heat treatment proceeded within 100 minutes at 100 ° C. at an elevated rate of 100 ° C./min. In addition, the microwave used a microwave heat treatment furnace operated at a frequency of 2.45 GHz and a power of 2 kW.

< Example 17 >

In Example 17, the heat treatment temperature was changed to 300 ° C. in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 18 >

In Example 18, the heat treatment temperature was changed to 600 ° C. in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

Furthermore, in order to investigate the effect of the temperature increase rate on the synthesis of powder, the production of barium titanate (BaTiO ₃ ) nanopowder was performed by varying the temperature increase rate.

< Example 19 >

In Example 19, the temperature increase rate was changed to 50 ° C./min in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 20 >

In Example 20, the temperature increase rate was changed to 50 ° C./min in Example 11, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 21 >

In Example 21, the temperature increase rate was changed to 50 ° C./min in Example 12, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 22 >

In Example 22, the temperature increase rate was changed to 50 ° C./min in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 23 >

In Example 23, the temperature increase rate was changed to 50 ° C./min in Example 14, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 24 >

In Example 24, the temperature increase rate was changed to 50 ° C./min in Example 15, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 25 >

In Example 25, the temperature increase rate was changed to 50 ° C./min in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 26 >

In Example 26, the temperature increase rate was changed to 50 ° C./min in Example 17, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 27 >

In Example 27, the temperature increase rate was changed to 50 ° C./min in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 28 >

In Example 28, the temperature increase rate was changed to 10 ° C./min in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 29 >

In Example 29, the temperature increase rate was changed to 10 ° C./min in Example 11, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 30 >

In Example 30, the temperature increase rate was changed to 10 ° C./min in Example 12, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 31 >

In Example 31, the temperature increase rate was changed to 10 ° C./min in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 32 >

In Example 32, the temperature increase rate was changed to 10 ° C./min in Example 14, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 33 >

In Example 33, the temperature increase rate was changed to 10 ° C./min in Example 15, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 34 >

In Example 34, the temperature increase rate was changed to 10 ° C./min in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 35 >

In Example 35, the temperature increase rate was changed to 10 ° C./min in Example 17, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Example 36 >

In Example 36, the temperature increase rate was changed to 10 ° C./min in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

In addition, in order to determine the effect of the heat treatment time on the powder synthesis, barium titanate (BaTiO ₃ ) nano-powder was prepared by varying the heat treatment time.

< Example 37 >

In Example 37, the heat treatment time was changed to 30 minutes in <Example 10>, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the black label in FIG. 9 (b).

< Example 38 >

In Example 38, the heat treatment time was changed to 30 minutes in <Example 11>, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the red label in FIG. 9 (b).

< Example 39 >

In Example 39, the heat treatment time was changed to 30 minutes in <Example 12>, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the blue label in FIG. 9 (b).

< Example 40 >

In Example 40, the heat treatment time was changed to 30 minutes in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the black label in FIG. 9 (c).

< Example 41 >

In Example 41, the heat treatment time was changed to 30 minutes in <Example 14>, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the red label in FIG. 9 (c).

< Example 42 >

In Example 42, the heat treatment time was changed to 30 minutes in Example 15, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the blue label in FIG. 9 (c).

< Example 43 >

In Example 43, the heat treatment time was changed to 30 minutes in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the black label in FIG.

< Example 44 >

In Example 44, the heat treatment time was changed to 30 minutes in <Example 17>, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the red label in FIG.

< Example 45 >

In Example 45, the heat treatment time was changed to 30 minutes in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 30 minutes in the blue label in FIG.

< Example 46 >

In Example 46, the heat treatment time was changed to 60 minutes in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the black label in FIG. 9 (b).

< Example 47 >

In Example 47, the heat treatment time was changed to 60 minutes in Example 11, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the red label in FIG. 9 (b).

< Example 48 >

In Example 48, the heat treatment time was changed to 60 minutes in Example 12, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the blue label in FIG. 9 (b).

< Example 49 >

In Example 49, the heat treatment time was changed to 60 minutes in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the black label in FIG. 9 (c).

< Example 50 >

In Example 50, the heat treatment time was changed to 60 minutes in Example 14, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the red label in FIG. 9 (c).

< Example 51 >

In Example 51, the heat treatment time was changed to 60 minutes in Example 15, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the blue label in FIG. 9 (c).

< Example 52 >

In Example 52, the heat treatment time was changed to 60 minutes in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the black label in FIG.

< Example 53 >

In Example 53, the heat treatment time was changed to 60 minutes in Example 17, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the red label in FIG.

< Example 54 >

In Example 54, the heat treatment time was changed to 60 minutes in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 60 minutes in the blue label in FIG.

< Example 55 >

In Example 55, the heat treatment time was changed to 120 minutes in Example 10, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the black label in FIG. 9 (b).

< Example 56 >

In Example 56, the heat treatment time was changed to 120 minutes in Example 11, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the red label in FIG. 9 (b).

< Example 57 >

In Example 57, the heat treatment time was changed to 120 minutes in Example 12, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the blue label in FIG. 9 (b).

< Example 58 >

In Example 58, the heat treatment time was changed to 120 minutes in Example 13, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the black label in FIG. 9 (c).

< Example 59 >

In Example 59, the heat treatment time was changed to 120 minutes in Example 14, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the red label in FIG. 9 (c).

< Example 60 >

In Example 60, the heat treatment time was changed to 120 minutes in Example 15, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the blue label in FIG. 9 (c).

< Example 61 >

In Example 61, the heat treatment time was changed to 120 minutes in Example 16, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the black label in FIG.

< Example 62 >

In Example 62, the heat treatment time was changed to 120 minutes in Example 17, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the red label in FIG.

< Example 63 >

In Example 63, the heat treatment time was changed to 120 minutes in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is 120 minutes in the blue label in FIG.

< Example 64 >

In Example 64, the heat treatment time of Example 10 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the black label in FIG. 9 (b) is within 1 minute.

< Example 65 >

In Example 65, the heat treatment time of Example 11 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is within 1 minute among red marks in FIG. 9 (b).

< Example 66 >

In Example 66, the heat treatment time of Example 12 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the blue label in FIG. 9 (b) is within 1 minute.

< Example 67 >

In Example 67, the heat treatment time of Example 13 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the black label in FIG. 9 (c) is within 1 minute.

< Example 68 >

In Example 68, the heat treatment time of Example 14 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is within 1 minute among red marks in FIG. 9 (c).

< Example 69 >

In Example 69, the heat treatment time of Example 15 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the blue label in FIG. 9 (c) is within 1 minute.

< Example 70 >

In Example 70, the heat treatment time of Example 16 was changed to within 1 minute, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the black label in FIG. 9 (a) is within 1 minute.

< Example 71 >

In Example 71, the heat treatment time was changed to within 1 minute in Example 17, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value is within 1 minute among red marks in FIG. 9 (a).

< Example 72 >

In Example 72, the heat treatment time was changed to within 1 minute in Example 18, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders. This corresponds to the point where the x-axis value of the blue label in FIG. 9 (a) is within 1 minute.

Further, in order to determine the effect of the heat treatment method according to the difference in the number of hydrates of the barium raw material powder on the synthesis of the powder, barium titanate (BaTiO ₃ ) nano-powder was prepared by changing the heat treatment method.

< Comparative Example 4 >

Ba (OH) ₂ H ₂ O (BH 1) was used as a first raw material powder of <Comparative Example 4>. As the second raw material powder, TiO ₂ xH ₂ O (TH) was used. The first and second raw material powders were mixed using a stirrer. The mixed mixture was molded by applying a pressure of 600 kg / cm ² . The manufactured molded article was subjected to a general heat treatment process. General electrical heat treatment was performed within 300 minutes at 300 ° C. at a rate of temperature increase of 5 ° C./min.

< Comparative Example 5 >

In Comparative Example 5, the heat treatment temperature was changed to 600 ° C. in Comparative Example 4, and other conditions were controlled in the same manner to prepare barium titanate (BaTiO ₃ ) nanopowders.

< Comparative Example 6 >

In Comparative Example 6, the first raw material powder was changed to Ba (OH) ₂ (BH0) in <Comparative Example 4>, and barium titanate (BaTiO ₃ ) nanopowder was prepared under the same conditions.

< Comparative Example 7 >

In Comparative Example 7, the first raw material powder was changed to Ba (OH) ₂ (BH0) in Comparative Example 5, and barium titanate (BaTiO ₃ ) nanopowder was prepared under the same conditions.

In addition, in order to determine the effect of the powder synthesis method, the barium titanate (BaTiO ₃ ) nano-powder was prepared by using a hydrothermal synthesis method.

< Comparative Example 8 >

In Comparative Example 8, Ba (OH) ₂ (BH0) was used as the first raw material powder in the autoclave, and TiO ₂ xH ₂ O (TH) was used as the second raw material powder. The first and second raw material powders were mixed using a hydrothermal synthesis method. In this case, the used solution was a mixture of tertiary distilled water and ethanol, and the molar ratio of Ba: Ti was added at 1: 1 to react at 180 ° C. for 6 hours.

< Experimental Example 1 > Crystal Structure Characteristics of Prepared Powders-1

<Experimental Example 1> In, the raw material powder of barium and titanium, barium titanate (BaTiO ₃₎ In order to examine the effects of the manufacturing nanostructured powder, the barium titanate produced in <Example 1> to <Example 4> (BaTiO ₃ X-ray diffraction analysis of the nano powder was performed. 2 is a graph showing the results of <Experimental Example 1>.

Referring to FIG. 2, in the BH8TH sample of Example 1, a phase in which barium titanate (a: BaTiO ₃ ) and barium carbonate (b: BaCO ₃ ) is mixed is detected, and in the case of the BH8TO sample of Example 2, ortho A phase in which barium titanate (e: Ba ₂ TiO ₄ ), barium carbonate (b: BaCO ₃ ) and titanium dioxide (c: rutile-TiO ₂ ) was mixed was confirmed.

The detected barium titanate (a: BaTiO ₃ ) was identified as a cubic crystal structure containing some tetragonal phases with broad peaks at 45 ° coming from nano-sized barium titanate (BaTiO ₃ ) powder. On the other hand, in the case of the BCTH sample of <Example 3> and the BCTO sample of <Example 4>, the barium carbonate (b: BaCO ₃ ) phase, which is a raw material of barium, was most strongly detected. In addition, the BCTH sample of <Example 3> produced a titanium dioxide (d: anatase-TiO ₂ ) phase, and the BCTO sample of <Example 4> had the same titanium dioxide (c: rutile-TiO ₂ ) as the raw material powder of titanium. Detected.

Depending on the raw powder, the BH8 source reacts with TH and TO to form the barium titanate (a: BaTiO ₃ ) and barium ortho titanate (e: Ba ₂ TiO ₄ ) phases, which are reactants of barium and titanium ions, and react with some air Due to the barium carbonate (b: BaCO ₃ ) seems to be formed.

For BC sources, no additional reaction-related phases were formed between barium and titanium, regardless of the Ti source type.

In other cases, the TH source produces a barium titanate (a: BaTiO ₃ ) phase only in reaction with BH in the reaction of BH8 and BC, and in the case of BC, the TH source generates a phase transition to titanium dioxide (d: anatase-TiO ₂ ) phase. It was.

On the other hand, in the case of TO, most of the initial state of titanium dioxide (c: rutile-TiO ₂ ) phase remained and only reacted with the formation of some barium ortho titanate (e: Ba ₂ TiO ₄ ) phase in reaction with BH8. These results show that a large difference in reactivity with the titanium raw material powder occurs depending on the type of raw material powder of barium.

BH8 and TH, unlike BC and TO, contain polar bonds, such as H ₂ O and OH ^−, and therefore appear to be easy to react to microwaves.

From the results of Experimental Example 1, barium (Ba) and titanium (Ti) sources containing hydrates in the production of barium titanate (a: BaTiO ₃ ) powder may be easily generated to form a barium titanate (a: BaTiO ₃ ) phase. Confirmed.

< Experimental Example  2> Crystal Structure of the Prepared Powder-2

In <Experimental Example 2>, in order to examine the effect of the heat treatment temperature and the heat treatment method on the production of barium titanate (BaTiO ₃ ) powder, <Example 1>, <Example 5>, <Example 6> and <Comparative Example X-ray diffraction analysis of the crystal structure of the barium titanate (BaTiO ₃ ) nanopowder prepared in 1> to <Comparative Example 3> was performed. 3 and 4 are graphs showing the results of Experimental Example 2. FIG.

Referring to FIG. 3, in the microwave heat treatment disclosed in <Example 1>, <Example 5>, and <Example 6>, barium titanate (a: BaTiO ₃ ) and barium carbonate (b: BaCO) from 100 ° C to 600 ° C ₃ ) It was confirmed that the peak intensity of barium titanate (a: BaTiO ₃ ) was relatively increased as the phases were mixed and the heat treatment temperature was increased.

On the other hand, referring to Figure 4, when performing the heat treatment in the electric furnace described in Comparative Example 1 to Comparative Example 3, the barium carbonate (b: BaCO ₃ ) and titanium dioxide in the sample at 300 ℃ of <Comparative Example 1> (c: anatase-TiO ₂ ) peaks were detected, and barium carbonate (b: BaCO ₃ ) and barium titanate (a: BaTiO ₃ ) were produced in the sample at 600 ° C. in Comparative Example 2, but barium titanate (a: BaTiO) was produced. ₃₎ the main peak in the peak intensity is barium carbonate at 31.3 ° in the (b: BaCO ₃₎ in very low <Comparative example 3> in the sample of 800 ℃ barium titanate (a in the comparison: the intensity of the main peak of the BaTiO ₃₎ It can be seen that is higher than the barium carbonate (b: BaCO ₃ ).

In <Experimental Example 2>, the effect of microwave heat treatment time on the production of barium titanate (BaTiO ₃ ) nanopowders was confirmed by comparing the samples of <Example 7> to <Example 9>. 5 is a graph showing the results of X-ray diffraction analysis of the sample described above.

5 is a graph comparing <Example 7> to <Example 9>. Referring to FIG. 5, in a sample having a synthesis time of less than one minute, after the microwave heat treatment, barium titanate (a: BaTiO ₃ ) and barium carbonate (b: BaCO ₃ ) phases are mixed, and the intensity of the main peak of barium titanate (BaTiO ₃ ) is increased. You can see that it is very low.

On the other hand, synthesis time of 30 minutes after the same manner as in less than a minute tea calculation barium case increased (a: BaTiO ₃₎ and barium carbonate (b: BaCO ₃₎ onto the to be mixed, but the barium titanate of: (a BaTiO ₃₎ It was found that the intensity of the main peak increased relatively compared to within 1 minute. When the synthesis time is 60 minutes, it was confirmed that the same aspect as the result of the synthesis time is 30 minutes.

From the results of Experimental Example 2 described above, it is judged that the BH8TH sample can be prepared for the barium titanate (BaTiO ₃ ) nanopowder at a heat treatment temperature of 100 ° C. by a microwave heat treatment method.

< Experimental Example  3> Crystal Structure of the Prepared Powder-3

In Experimental Example 3, in order to examine the effects of the number of hydrates and the microwave heat treatment temperature of the barium raw material powder on the synthesis of the barium titanate (BaTiO ₃ ) nanopowder, the powders of Examples 10 to 15 were prepared. After preparation, X-ray diffraction analysis was performed. 6 is a graph showing the results of X-ray diffraction analysis.

Referring to FIG. 6 (a), in the sample (BH1TH) of <Example 10> to <Example 12>, in which the barium raw material powder has one hydrate, at the microwave heat treatment temperatures of 100 ° C. and 300 ° C., the two graphs at the bottom, respectively. There is a mixed phase of barium titanate (a: BaTiO ₃ ) and barium carbonate (b: BaCO ₃ ), and the main peak intensity of barium titanate (a: BaTiO ₃ ) is relatively higher than that of barium carbonate (b: BaCO ₃ ). A large one was confirmed. In addition, in the case of the upper 600 ° C sample, it was confirmed that an additional barium ortho titanate (c: Ba ₂ TiO ₄ ) phase was formed together with the mixed phases.

Referring to FIG. 6 (b), in the samples (BH0TH) of <Example 13> to <Example 15> in which the hydrate of the barium raw material powder is zero, titanic acid at all temperature ranges of microwave heat treatment temperatures 100, 300, and 600 ° C. A mixed phase of barium (a: BaTiO ₃ ) and barium ortho titanate (c: Ba ₂ TiO ₄ ) exists, and the main peaks of barium titanate (a: BaTiO ₃ ) and barium ortho titanate (c: Ba ₂ TiO ₄ ) It was confirmed that the intensity did not show a big difference regardless of the temperature.

7 is an X-ray diffraction pattern of barium titanate (BaTiO ₃ ) nanoparticles prepared by microwave heat treatment at BH0TH, BH1TH and BH8TH samples of Examples 10 to 18 at 100 ° C., respectively. Based on the results of the analysis, the Scherrer formula is used to calculate the size of the crystal.

Scherrer's formula for calculating the crystal size used Equation 1 below.

[Equation 1]

D = 0.9λ / Bcosθ

(D: crystal size, λ: wavelength of X-ray, B: half width of diffraction beam, θ: angle of diffraction beam)

Referring to FIG. 7 again, when the microwave heat treatment was performed at 100 ° C., the crystal size was about 11 nm for the BH0TH sample, about 16 nm for the BH1TH sample, and about 21 nm for the BH8TH sample. Increased. When the heat treatment temperature was increased to 600 ℃, the crystal size of the BH8TH and BH1TH samples increased to about 27 nm, it can be seen that the BH0TH samples to 17 nm.

FIG. 8 shows the effects of varying heating rate on barium titanate (BaTiO ₃ ) nanopowders for BH0TH, BH1TH and BH8TH in samples having different numbers of hydrates of the barium raw material powders prepared in Examples 19 to 36. Is a graph showing the phase fraction. Equation 2 was used to calculate the result of the graph.

&Quot; (2) &quot;

Intensity ratio (%) = I _BaTiO3 / (I _BaTiO3 + I _Secondary )

(I _BaTiO3 : Main peak intensity of BaTiO ₃ , I _Secondary : Sum of main peak strength of all phases except BaTiO ₃ )

In the case of the BH8TH sample shown in FIG. 8 (a), the fraction of barium titanate (BaTiO ₃ ) is about 10% in the low temperature region of 100 and 300 ° C., but there is no significant difference depending on the temperature increase rate. At ℃ / min, the fraction of barium titanate (BaTiO ₃ ) was the highest at about 80%. On the other hand, when the temperature increase rate is 10 ℃ / min it was confirmed that the fraction of barium titanate (BaTiO ₃ ) is about 15%, and there is no significant difference with the low temperature region.

The BH1TH sample shown in FIG. 8 (b) showed a high phase fraction of barium titanate (BaTiO ₃ ) of about 75% or more at 100 ° C. regardless of the temperature increase rate, but the temperature increase rate was 10 ° C./min at 300 and 600 ° C. FIG. When the barium ortho titanate (Ba ₂ TiO ₄ ) phase is generated it can be seen that the fraction of the barium titanate (BaTiO ₃ ) phase is lowered. In addition, a small amount of barium ortho titanate (Ba ₂ TiO ₄ ) phase was generated at a heat treatment temperature of 600 ° C. at a heating rate of 50 and 100 ° C./min, indicating a slight decrease in fraction.

In the case of the BH0TH sample shown in FIG. 8 (c), the barium titanate (BaTiO ₃ ) phase is low at about 50 to 65% in all temperature ranges of 100, 300, and 600 ° C regardless of the heating rate and the heat treatment temperature. This is confirmed by the influence of the barium ortho titanate (Ba ₂ TiO ₄ ) phase formed from the temperature of 100 ° C.

9 is a heat treatment time changed at a microwave heat treatment temperature rising rate of 100 ° C./min for BH0TH, BH1TH and BH8TH samples having different numbers of hydrates of the barium raw material powders prepared in Examples 37 to 72. It is a graph showing the effect on the barium titanate (BaTiO ₃ ) nanopowder in terms of phase fraction. Equation 2 described above was used to calculate the result of the graph.

The sample of BH8TH shown in FIG. 9 (a) showed a constant phase fraction of about 80% of barium titanate (BaTiO ₃ ) in all of 0 to 120 minutes in the microwave heat treatment condition of 600 ° C. In the case of a microwave heat treatment conditions of 100, 300 ℃ there represents the fraction of the low barium titanate (BaTiO ₃₎ from 20 to 30% of the heat treatment time of 0 minutes, and when the heat treatment time increased to 60 minutes, barium titanate (BaTiO ₃₎ The percentage of s increased to about 65%.

In the BH1TH sample shown in FIG. 9 (b), the change of the phase fraction according to the heat treatment time was confirmed finely, about 82% under microwave heat treatment conditions of 100 and 300 ° C., and about 90% under microwave heat treatment conditions of 600 ° C. It showed a high phase fraction of barium titanate (BaTiO ₃ ).

In the BH0TH sample shown in FIG. 9 (c), the BH0TH sample exhibited a phase fraction of barium titanate (BaTiO ₃ ) of about 50% at three conditions of a heat treatment temperature of 100,300 and 600 ° C. at 0 minutes. However, as the heat treatment time was continued for 30 minutes or more, different phase ratios of about 40% at 100 ° C, about 50% at 300 ° C, and about 70% at 600 ° C were shown.

Through the results of <Experimental Example 3>, when performing the microwave heat treatment in the low temperature region, it was confirmed that the BH1TH sample was most effective in the preparation of the barium titanate (BaTiO ₃ ) nanopowder. In addition, it can be confirmed that the BH0TH sample in the low temperature region of 100 and 300 ° C and the BH8TH sample in the high temperature region of 600 ° C are suitable for the preparation of the barium titanate (BaTiO ₃ ) nanopowder.

< Experimental Example  4> Crystal Structure of the Prepared Powder-4

In Experimental Example 4, the effects of different heat treatment methods on the synthesis of barium titanate (BaTiO ₃ ) nanopowders were confirmed for BH0TH, BH1TH and BH8TH samples having different numbers of hydrates of the barium raw material powder. 10 is a graph showing the results of <Experimental Example 4> in the phase fraction.

10 shows the results of samples subjected to heat treatment in a general electric furnace. In particular, Fig. 10 (a) shows <Comparative Example 4> and <Comparative Example 5>, and Fig. 10 (b) shows <Comparative Example 6> and <Comparative Example 7>. 10 (a) and 10 (b), when the heat treatment is performed with a general electric furnace, a barium carbonate (b: BaCO ₃ ) phase is generated at 300 ° C., and an additional barium titanate (a: BaTiO ₃ ) phase is formed at 600 ° C. You can see it created.

<Experimental Example 4> Through the results, it can be seen that there is no difference according to the number of hydrates of the barium raw material powder in the case of a general electric furnace heat treatment.

< Experimental Example  5> Crystal Structure of the Prepared Powder-5

In Experimental Example 5, a nanopowder according to Comparative Example 8 was prepared, and then X-ray diffraction analysis was performed to confirm the crystal structure. The results are then compared and shown in FIG. 11. Referring to FIG. 11, powders prepared in Example 10 and Comparative Example 8 produced cubic barium titanate (a: BaTiO ₃ ) and barium carbonate (b: BaCO ₃ ) phases. In the case of confirming the crystal state by comparing the peaks, the main peak intensity of barium titanate (a: BaTiO ₃ ) was higher than that of barium carbonate (b: BaCO ₃ ) compared to <Comparative Example 8> in the case of <Example 10>. It is confirmed that the high barium titanate (a: BaTiO ₃ ) phase is relatively well prepared.

Through the results of Experimental Example 5, the method of preparing barium titanate (BaTiO ₃ ) nanopowders using microwave heat treatment was performed to produce barium titanate (BaTiO ₃ ) nanopowders having crystallinity as good as that of hydrothermal synthesis. It seems to be possible.

< Experimental Example  6> Shape characteristics of the prepared powder

In Experimental Example 6, a photograph of the powder prepared in order to confirm the particle shape and size of the powder and measured by a high resolution scanning electron microscope is shown in FIG. 12. 12 (a) shows a nano powder prepared by microwave heat treatment at 100 ℃ condition of <Example 5>, Figure 12 (b) is prepared through a general electrical heat treatment at 600 ℃ condition of <Comparative Example 2> A nano powder is shown, and FIG. 12 (c) shows a nano powder prepared by the hydrothermal synthesis method of Comparative Example 8. FIG.

12 (a), the barium titanate (BaTiO ₃ ) nanopowder particles prepared according to Example 5 have a spherical shape with an average particle diameter of 26 ± 8 nm. Meanwhile, referring to FIG. 12 (b), the barium titanate (BaTiO ₃ ) nanopowder particles prepared according to Comparative Example 2 have a heterogeneous shape and an average particle diameter of 320 ± 50 nm due to particle growth. You can check it. In addition, referring to FIG. 12 (c), the barium titanate (BaTiO ₃ ) nanopowder particles prepared according to Comparative Example 8 have a spherical shape, and an average particle diameter thereof is 54 ± 5 nm.

Through the results of Experimental Example 6, it can be seen that when the nanopowder of barium titanate (BaTiO ₃ ) is manufactured at a low temperature using microwave heat treatment, a powder having a size of 30 nm or less is synthesized.

< Experimental Example  7> Dielectric Properties of Prepared Powders

In Experimental Example 7, capacitance values for evaluating the dielectric properties of the barium titanate (BaTiO ₃ ) nanopowders are shown in Table 1 below. In addition, the barium titanate (BaTiO ₃ ) powder having a pure tetragonal phase was set as a reference powder to compare the capacitance values. In order to measure the capacitance value, each powder was prepared with a ethanol-based mixed solution, followed by spin coating a silicon (Si) substrate to prepare a film. Electrodes were prepared at the top of the prepared film and the bottom of the silicon substrate, and capacitance values were measured using a multi-frequency impedance analyzer.

[Table 1]

Referring to [Table 1], the reference powder of barium titanate (BaTiO ₃ ) having a tetragonal phase exhibited the highest value with a capacitance of 0.704 nF, and 0.602 nF for <Example 10> after microwave heat treatment. The electrolytically heat treated <Comparative Example 5> exhibited the lowest value among the samples with a capacitance of 0.320 nF and the Comparative Example 8 produced by the hydrothermal synthesis method with a barium titanate (BaTiO ₃ ) nanopowder of 0.277 nF. It was.

Although the present invention has been described in detail through the representative embodiments above, those skilled in the art to which the present invention pertains will appreciate that various modifications can be made without departing from the scope of the present invention. will be. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by all changes or modifications derived from the claims and the equivalent concepts as well as the following claims.

S1: a) Raw powder preparation step
S3: b) mixture formation step
S5: c) step of forming molded body
S7: d) microwave heat treatment step

Claims (10)

In the method for producing the barium titanate nanopowder using the solid phase synthesis method,
a) preparing a first raw material powder of Ba (OH) ₂ 8H ₂ O and a second raw material powder of TiO ₂ xH ₂ O;
b) mixing the first raw material powder and the second raw material powder prepared in step a) to form a mixture;
c) preparing the mixture formed in step b) into a shaped body; And
d) a method of producing barium titanate nanopowder comprising the step of microwave heat treatment of the molded article prepared in step c) at a temperature range of 100 to 800 ℃.
The method of claim 1,
In step d),
A method for producing barium titanate nanopowder using microwaves having a frequency range of 2.0 to 2.5 GHz.
delete The method of claim 1,
In step d),
Method for producing a barium titanate nano powder to perform the heat treatment for 1 to 120 minutes.
The method of claim 1,
In step d),
Method for producing the barium titanate nanopowder is subjected to the heat treatment at a temperature rising rate of 5 to 120 ℃ / min.
delete delete The method of claim 1,
The step b)
A method for producing barium titanate nanopowder, wherein the initial source of barium and the raw material powder of titanium are mixed at a ratio of 1: 1 mol%.
The method of claim 1,
The step b)
Method for producing a barium titanate nanopowder having a mixing time of the raw material powder is 1 to 30 minutes.
The method of claim 1,
The step c)
Method for producing a barium titanate nanopowder having a pressure applied to the mixture is 200 to 800 Kg / cm ² .

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