KR20170124173A - Synthesis method of oxide powder with perovskite structure and oxide powder formed by the synthesis method - Google Patents

Abstract

A method for manufacturing an oxide powder having a perovskite structure according to the present invention comprises the following steps: preparing a metal precursor solution by mixing ethanol with a lanthanide metal precursor, a barium (Ba) precursor, a cobalt (Co) precursor, and a copper (Cu) precursor; performing a sol-gel reaction by mixing an ethylenediaminetetraacetic acid (EDTA) solution containing EDTA and ammonia water, the metal precursor solution and citric acid; drying a gelled compound formed by a sol-gel reaction; and calcining the dried compound. According to the method for manufacturing an oxide powder having a perovskite structure according to the present invention, it is possible to remarkably shorten the time required for gelation in a sol state, minimize the size of particles formed at the beginning to be controlled to the particle size of 50 nm or less.

Description

TECHNICAL FIELD The present invention relates to a method for producing an oxide powder having a perovskite structure and an oxide powder prepared by the method. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide powder having a perovskite structure,

The present invention relates to a method for producing an oxide powder having a perovskite structure and an oxide powder produced thereby, and more particularly, to a method for producing an oxide powder having a perovskite structure, which is used as a mixed conducting electrode, Lt; / RTI >

An ethylenediaminetetraacetic acid (EDTA) -citric acid complexing process is a typical method for synthesizing an oxide having a multi-component perovskite structure including at least three components, - a kind of gel (sol-gel) method.

In the EDTA-citric acid complex process, EDTA and citric acid are used as chelating agents. A metal nitrate-based precursor corresponding to the stoichiometry of the desired composition is dissolved in distilled water and EDTA and citric acid are added to react. The metal nitride precursor has the advantage of easily ionizing metal cations by dissolving them in distilled water.

However, according to the EDTA-citric acid complex process as described above, it takes a long time until the distilled water is evaporated and gelled in the sol state in the process of stirring and reacting the substances, which increases the entire process time. Also, in the gelling process, the agglomeration phenomenon occurs between EDTA, which is a chelating agent of the chelating reaction, and the chelate, which binds citrate to the metal cation, and agglomeration occurs even between the crystallized powders due to the agglomeration phenomenon. As a result, although particles having a particle size of about 10 nm are synthesized, they have a small specific surface area.

It is an object of the present invention to provide a method for producing an oxide powder having a perovskite structure as a material having a desired composition without shortening the entire process time and without causing agglomeration, and to provide an oxide powder produced thereby.

A method for producing an oxide powder having a perovskite structure for an object of the present invention comprises mixing a lanthanoid metal precursor, a barium precursor, a cobalt precursor and a copper precursor with ethanol to prepare a metal precursor solution A step of preparing a sol-gel reaction by mixing an EDTA solution containing ethylenediaminetetraacetic acid (EDTA) and ammonia water, a metal precursor solution and citric acid, Drying the compound, and calcining the dried compound.

In one embodiment, the step of performing the sol-gel reaction may be carried out at a pH of 9 to 10. [

In one embodiment, performing the sol-gel reaction comprises mixing the EDTA solution with the metal precursor solution, mixing the EDTA solution with the metal precursor solution in the presence of citric acid, Gelling the sol formed thereby.

The oxide powder having a perovskite structure prepared by the above method has a layered perovskite structure of LnBaCo _(2-x) Cu _x O _{5 + δ} type (0 <x <2, where Ln represents Pr or Sm) It has a skate structure.

In one embodiment, the diameter of the oxide powder may be 50 nm or less.

According to the method for producing an oxide powder having a perovskite structure of the present invention, it is possible to remarkably shorten the time spent for gelation in a sol state, minimize the size of particles formed at the beginning, Can be controlled to 50 nm or less. Further, according to the production method of the present invention, the aggregation phenomenon does not substantially occur, and thus the specific surface area of oxide particles finally produced can be increased.

FIG. 1 is a flowchart illustrating a method of manufacturing an oxide powder having a perovskite structure according to an embodiment of the present invention. Referring to FIG.
2 is a transmission electron microscope (TEM) photograph of a sample prepared according to Example 1 of the present invention and a comparative sample prepared according to Comparative Example 1. FIG.
3 is a TEM photograph of a sample prepared according to Example 2 of the present invention and a comparative sample prepared according to Comparative Example 2. FIG.
4 is an X-ray diffraction (XRD) analysis graph of a sample prepared according to Example 2 of the present invention and a comparative sample prepared according to Comparative Example 2. Fig.
FIG. 5 is a graph showing XRD analysis graphs for explaining product changes according to changes in acidity in the process of producing an oxide powder according to the present invention.
6 is a graph showing polarization resistance characteristics of a sample prepared according to Example 2 of the present invention and a comparative sample prepared according to Comparative Example 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the term "comprises" or "having ", etc. is intended to specify that there is a feature, step, operation, element, part or combination thereof described in the specification, , &Quot; an &quot;, &quot; an &quot;, &quot; an &quot;

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

FIG. 1 is a flowchart illustrating a method of manufacturing an oxide powder having a perovskite structure according to an embodiment of the present invention. Referring to FIG.

1, a metal precursor solution and EDTA (ethylenediaminetetraacetic acid) solution (EDTA-NH ₃ ) are prepared to prepare an oxide powder having a perovskite structure containing at least three kinds of metal components, Mix.

The metal precursor solution is prepared by mixing at least three different metal precursors with ethanol and ethyl alcohol. Ethanol disperses the metal precursors and ionizes the metal precursors to form metal ions. When distilled water is used as a solvent for forming a metal ion, the time required for evaporating and gelling the distilled water in a subsequent step of gelating the sol becomes longer, and the entire process time is prolonged. Thus, the metal precursors can be dispersed in ethanol to solve such a problem. The metal precursor solution includes a lanthanide metal precursor, a barium precursor, a cobalt precursor, and a copper precursor. As the lanthanide group metal included in the lanthanide metal precursor, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yn or Lu can be mentioned. In particular, Pr, Nd, Pm, Sm, Eu or Gd can be used as the lanthanide metal, and preferably Pr, Nd or Gd can be used.

_(2-x) Cu _x O _{5 + δ} form (0 < x < 2, and the like ₎ by using the lanthanide metal precursor, the Ba precursor, the cobalt precursor and the copper precursor. And Ln represents a lanthanide metal) can be produced. Here, x may vary depending on the content of the cobalt precursor and the copper precursor to be mixed. The perovskite structure may be a layered perovskite structure.

The EDTA solution (EDTA-NH ₃ ) can be prepared by adding ammonia water (NH ₄ OH) to EDTA and mixing.

When the EDTA solution (EDTA-NH ₃ ) is mixed with the metal precursor solution prepared as described above, it becomes a liquid phase similar to the sol in a liquid state. When citric acid is added to a mixture having a liquid phase similar to a sol, the phase substantially changes to a sol which can be referred to as a sol. In this state, the gel is continuously stirred to form a gel. After mixing citric acid with the mixture having a liquid phase similar to the sol, stirring is performed until the mixture becomes a transparent or translucent sol, and stirring is continued to form a gel. Each of the step of forming the sol and the step of gelling the sol may be performed at a temperature of 50 to 70 캜.

In the gelling step, when the metal precursor solution contains distilled water, agglomeration phenomenon occurs between EDTA, which is a chelating agent of the chelating reaction, and the chelate, which binds citrate to the metal cation, However, in the present invention, the coagulation phenomenon can be minimized by using ethanol in the preparation of the metal precursor solution, so that the coagulation between the crystallized powders can be minimized.

The pH condition for mixing the citric acid to form a sol is preferably 9 to 10. When the above process is carried out at a pH outside the range of 9 to 10, there is a problem that a compound having a side structure other than the perovskite structure is formed. However, when the process is performed at a pH of 9 to 10, Oxide structure is formed.

The gel may then be dried at 200-300 DEG C to obtain a solid product (a precursor of a solid oxide powder).

The solid product is calcined at a temperature of at least 450 캜, whereby an oxide powder can be formed. As the solid product crystallizes in the calcination process to form metal oxide particles, a metal oxide powder is formed. The temperature condition of the calcination process may be from 450 캜 to 1,000 캜. In the case of using distilled water as the metal precursor solution, the temperature condition of the calcination step should be at least 1,000 ° C., but metal oxide powder can be formed by calcination at 450 ° C. to 1,000 ° C. by using ethanol instead of distilled water. Most preferably, it is calcined at 950 DEG C to form a metal oxide powder.

The perovskite structure powder produced according to the above-described process has a perovskite structure and is remarkably superior in dispersibility than the case of forming a perovskite structure powder by the conventional sol-gel method At the same time, the specific surface area increases. In addition, the powder of the layered perovskite structure can be stably formed with high dispersibility. The perovskite structure powder having such characteristics has mixed ionic and mixed conductivity and can be used as a conductive oxide electrode of a solid oxide battery, thereby preventing the deterioration of the solid oxide battery and improving the characteristics thereof.

Example 1: Preparation of oxide powder sample 1

To prepare the four-component oxide PrBaCo _1.9 Cu _0.1 O _{5 + δ} form by using a Praseodymium (Pr) precursor, a Ba precursor, a Cobalt precursor and a Cu precursor, the precursor was weighed stoichiometrically , Dissolving them in ethanol, and then stirring the solution using a magnetic bar to prepare a precursor solution. In this case, Pr (NO ₃ ) ₂ .6H ₂ O was used as a praseodymium precursor, Ba (NO ₃ ) ₂ , Co (NO ₃ ) ₃ .6H ₂ O and Cu NO ₃ ) ₂ · 2.5H ₂ O, which were mixed at a molar ratio of 1: 1: 1.9: 0.1, respectively.

Subsequently, a mixed solution prepared by mixing EDTA with ammonia water was mixed with the precursor solution prepared above, citric acid was mixed with the mixed solution, and the mixed solution was stirred at 60 ° C to prepare a sol. At this time, pH was adjusted to pH 9 using ammonia water. The molar ratio of total metal cation of praseodymium ion, barium ion, cobalt ion and copper ion, EDTA and citric acid was 1: 1: 1.5.

Subsequently, at 60 캜, the sol was continuously stirred (maintaining a pH of 9) until the sol became gel, and when the gel was formed, a solid product was obtained after drying at 250 캜. The obtained solid product was calcined at 450 캜 to prepare an oxide powder sample 1.

Example 2: Preparation of Sample 2

Sample 2 was prepared in accordance with Example 2 of the present invention by performing the calcination process at 950 ° C in the same manner as Sample 1 was produced according to Example 1.

Comparison 1 and 2: Preparation of Comparative Samples 1 and 2

Comparative Sample 1 was prepared through substantially the same process as that of Sample 1 according to Example 1 except that the praseodymium precursor, barium precursor, cobalt precursor and copper precursor were dissolved in distilled water instead of ethanol.

Comparative Sample 2 was also prepared through substantially the same process as that of Sample 2 according to Example 2, except that the praseodymium precursor, barium precursor, cobalt precursor and copper precursor were dissolved in distilled water instead of ethanol.

Structural analysis: TEM analysis

A TEM photograph was taken for each of Samples 1 and 2 and Comparative Samples 1 and 2 prepared above. The results are shown in Fig. 2 and Fig.

FIG. 2 is a transmission electron microscope (TEM) photograph of a sample prepared according to Example 1 of the present invention and a comparative sample prepared according to Comparative Example 1, and FIG. 3 is a cross- And TEM photographs of a comparative sample prepared according to Comparative Example 2. FIG.

2 (a) and 2 (b) are for Comparative Sample 1, and Figures 2 (c) and 2 (d) are for Sample 1, Figures 3 (c) and 3 (d) are for sample 2.

Referring to FIGS. 2 and 3, it can be seen that, in the case of FIGS. 2 (a) and 2 (b), the powders composed of fine particles are formed without agglomeration in the powders (c) and (c) and (d) as compared with (a) and (b), it can be confirmed that there is no coagulation phenomenon of the powder. That is, in Comparative Samples 1 and 2 using distilled water as a solvent, the particles constituting the powder were severely aggregated, whereas in the case of the powder synthesized in the case of Samples 1 and 2 using ethanol, particles Can be confirmed directly by TEM photograph. That is, it can be confirmed that the aggregation phenomenon remarkably decreased. 3 (c) and (d) show that in the case of (a) and (b) in particular, the grain growth was excessively caused by the heat treatment at 950 ° C. due to the agglomeration occurring at calcination at 450 ° C., It can be seen that particles having a uniform size of about 50 nm are distributed due to less secondary particle growth.

XRD analysis-1

XRD analysis was performed on each of Sample 2 prepared according to Example 2 and Comparative Sample 2 prepared according to Comparative Example 2 above. The results are shown in Fig.

4 is an X-ray diffraction (XRD) analysis graph of a sample prepared according to Example 2 of the present invention and a comparative sample prepared according to Comparative Example 2. Fig.

In FIG. 4, the x-axis represents the diffraction angle and the y-axis represents the light intensity at the diffraction angle, the bottom graph of FIG. 4 is for comparative sample 2 and the top graph is for sample 2. FIG.

Referring to FIG. 4, it can be seen that intense diffraction peaks appear in the vicinity of the diffraction angles of 30 to 35 degrees in both the comparative sample 2 and the sample 2. That is, in the case of using distilled water or ethanol, the layered perovskite structure PrBaCo _1.9 Cu _0.1 O _{5 + delta} is formed as a solvent. In particular, it can be seen that, in the case of the sample 2, a diffraction peak having a remarkably strong intensity appears as compared with the comparative sample 2.

Examples 3 to 6: Preparation of Samples 3 to 6

Samples 3 to 6 were prepared through substantially the same steps as in the preparation of Sample 2 according to Example 2 of the present invention, except that the pH was adjusted to 7, 8, 10 and 11 respectively using ammonia water in the production process. Respectively.

XRD analysis -2

For each of Samples 2 to 6, XRD analysis was performed. The results are shown in Fig.

FIG. 5 is a graph showing XRD analysis graphs for explaining product changes according to changes in acidity in the process of producing an oxide powder according to the present invention.

5, (a) relates to sample 3, (b) and (c) relate to sample 4 and sample 5, (d) to sample 2, and (e) .

Referring to FIG. 5, it can be seen that (a) to (e) all show strongly intense diffraction peaks near diffraction angles of 30 ° to 35 ° as in FIG. However, in the case of (a), (b) and (e) of FIG. 5, it is understood that a layered perovskite structure is formed but a secondary phase is formed incidentally. That is, in the cases of (a), (b) and (e) of FIG. 5, there are more new peaks than the diffraction peaks shown in (c) and (d) It can be confirmed that it is relatively weak. Therefore, even when ethanol is used as the solvent, it can be confirmed that no side water is produced, and the most preferable pH range in which the layered perovskite structure PrBaCo _1.8 Cu _0.2 O _{5 + delta} is formed is 9 to 10.

Evaluation of polarization resistance

The characteristics of the polarization resistance at 750 ° C were evaluated for each of Sample 2 prepared according to Example 2 of the present invention prepared above and Comparative Sample 2 prepared according to Comparative Example 2. The results are shown in Fig.

6 is a graph showing polarization resistance characteristics of a sample prepared according to Example 2 of the present invention and a comparative sample prepared according to Comparative Example 2. FIG.

In Figure 6, "■ ethanol" is for sample 2 and "water"

Referring to FIG. 6, it can be seen that the resistance of Sample 2 using ethanol as a solvent is lower than that of Comparative Sample 2 using distilled water. That is, it can be confirmed that the sample 2 has a resistance value lowered by about 25% as compared with the comparative sample 2. These results can be attributed to the increase in the specific surface area as the dispersibility of the sample 2 is higher than the dispersibility of the comparative sample 2. That is, when Sample 2 is prepared using ethanol, it can be directly confirmed that the dispersibility is improved as compared with the case where Comparative Sample 2 is prepared by using distilled water.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It can be understood that it is possible.

Claims (5)

Preparing a metal precursor solution by mixing ethanol with a lanthanide metal precursor, a barium (Ba) precursor, a cobalt (Co) precursor, and a copper (Cu) precursor;
Performing a sol-gel reaction by mixing EDTA solution containing ethylenediaminetetraacetic acid (EDTA) and ammonia water, the metal precursor solution and citric acid;
Drying the gelled compound formed by said sol-gel reaction; And
And calcining the dried compound.
A method for producing an oxide powder having a perovskite structure.
The method according to claim 1,
The step of performing the sol-gel reaction
lt; RTI ID = 0.0 &gt; 9 &lt; / RTI &gt; to 10,
A method for producing an oxide powder having a perovskite structure.
The method according to claim 1,
The step of performing the sol-gel reaction
Mixing the EDTA solution with the metal precursor solution;
Mixing citric acid in a state where the EDTA solution and the metal precursor solution are mixed; And
Characterized in that it comprises the step of gelling the sol formed by mixing citric acid,
A method for producing an oxide powder having a perovskite structure.
An oxide powder having a layered perovskite structure of LnBaCo _(2-x) Cu _x O _{5 + delta} form (0 <x <2, wherein Ln represents Pr or Sm ₎ prepared according to the method of claim 1.
5. The method of claim 4,
Wherein the oxide powder has a diameter of 50 nm or less.
An oxide powder having a layered perovskite structure.

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