KR102743290B1 - Hetero-structured perovskite seeds absorbed with nanoparticles, mnufacturing method for the same and oriented knn ceramics manufactured using the same - Google Patents

Abstract

Disclosed are Pb-based perovskite seeds and a method for producing the same.
The Pb-based perovskite seed according to the present invention contains Na, Mg, and Pb, and has a composition of (Na _x Bi _0.4-x Pb _0.6 )(Ti _1-y Mg _y )O ₃ (provided that 0 < x ≤ 0.2 and 0.12 ≤ y < 0.15).

Description

HETERO-STRUCTURED PEROVSKITE SEEDS ABSORBED WITH NANOPARTICLES, MNUFACTURING METHOD FOR THE SAME AND ORIENTED KNN CERAMICS MANUFACTURED USING THE SAME

The present invention relates to a heterogeneous perovskite seed having nanoparticles adsorbed on its surface, a method for producing the same, and a KNN ceramic produced using the same.

A piezoelectric element is a device that can convert mechanical energy of the user into electrical energy, or conversely, electrical energy can be converted into mechanical energy by applying it to the piezoelectric element.

Piezoelectric elements are widely used as functional devices such as transformers, actuators, transducers, sensors, resonators, and filters due to their excellent piezoelectric properties.

Perovskite structures are most commonly used as piezoelectric elements.

Most piezoelectric elements having the above perovskite structure use a Pb(Zr,Ti)O ₃ composition or a Pb(Mg _1/3 Nb _2/3 )TiO ₃ composition, which mainly uses lead.

However, the above compositions have fundamental limitations in use due to the environmental and human toxicity of the lead (Pb) component.

Meanwhile, K _1-x Na _x NbO ₃ system (hereinafter referred to as KNN system) perovskite is an eco-friendly lead-free piezoelectric material that can replace existing lead-containing perovskites. However, it has the disadvantage of low properties compared to general polycrystalline ceramics.

Among the methods for manufacturing the above perovskite material, the TGG (Templated Grain Growth) method is a method in which a highly oriented seed is used as a template to grow polycrystalline powder with an orientation.

It is known that the piezoelectric properties of polycrystalline ceramics manufactured through oriented growth in the above TGG method are significantly increased due to oriented growth compared to the piezoelectric properties of non-oriented polycrystalline piezoelectric ceramics.

To date, the types of seeds used in the TGG process for manufacturing lead-free piezoceramics include BaTiO ₃ (BT), NaNbO ₃ (NN), and K _1-x Na _x NbO ₃ (KNN).

The biggest problem with the method of using the existing seeds as mentioned above is that the production of the seed itself is difficult (KNN seed) or the composition of the matrix powder and the seed are different (BaTiO ₃ (BT), NaNbO ₃ (NN) seed).

In particular, when the compositions of the seed and the matrix are significantly different (BaTiO ₃ (BT), NaNbO ₃ (NN) seed), it is difficult to orient the polycrystalline ceramic through the TGG process, and even if orientation is achieved, the piezoelectric sintered body may contain a large number of pores due to mutual diffusion between the components caused by the difference in composition between the seed and the matrix.

In addition, when the lattice constant mismatch between the seed and the matrix powder is large (BaTiO ₃ (BT), NaNbO ₃ (NN) seed), there is a problem that it is difficult for oriented growth to occur at the interface between the seed and the matrix.

The purpose of the present invention is to provide a perovskite seed having a novel structure that overcomes the above problems, a method for producing the seed, and a KNN-oriented ceramic using the seed.

Specifically, the purpose of the present invention is to provide a heterostructured perovskite seed having a composition similar to a ceramic matrix, a method for producing the seed, and a KNN-oriented ceramic using the seed.

More specifically, the purpose of the present invention is to provide a perovskite seed that provides a buffer layer between the seed and the ceramic matrix for the difference in composition between the seed and the matrix, a method for producing the seed, and a KNN-oriented ceramic using the seed.

The purposes of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be easily understood that the purposes and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

The heterostructure seed according to the present invention is a seed having a perovskite (ABO ₃ ) structure, and is characterized by including nanoparticles adsorbed on the surface of the seed.

Preferably, the seed may have a plate-like shape.

Preferably, the perovskite structure may include at least one of BaTiO ₃ (BT), (K,Na)NbO ₃ (KNN), and NaNbO ₃ (NN).

Preferably, the nanoparticles may have a composition of (K,Na)NbO ₃ (KNN).

A method for producing a heterostructure seed according to the present invention may include: (a) a step of producing a seed having a perovskite (ABO ₃ ) structure; (b) a step of mixing the perovskite seed and a raw material powder for nanoparticles and then performing solvothermal synthesis; (c) a step of washing the heterostructure seed including nanoparticles adsorbed on the surface of the seed having the perovskite structure formed in the synthesizing step (b).

Preferably, the perovskite structure seed manufactured in step (a) may include at least one of BaTiO ₃ (BT), (K,Na)NbO ₃ (KNN), and NaNbO ₃ (NN).

Preferably, the nanoparticles may have a composition of (K,Na)NbO ₃ (KNN).

The piezoelectric element according to the present invention has a matrix containing (K,Na)NbO ₃ (KNN) components, has a Lotgering factor (LF) value of 92% or more, and may have a piezoelectric constant (d ₃₃ ) of 150 or more.

A functional element according to the present invention includes the piezoelectric element.

The present invention can provide a heterostructure seed having a new structure and composition.

In addition, the heterostructure seed having the novel structure and composition of the present invention can provide an effect of dramatically improving the orientation and piezoelectric properties of KNN ceramics.

In addition, the present invention can provide a method for producing a perovskite seed that is very simple and has excellent orientation and piezoelectric properties.

In addition to the effects described above, specific effects of the present invention are described below together with specific matters for carrying out the invention.

Figure 1 is a schematic diagram of a topochemical molten-salt process.
Figure 2 illustrates the mechanism for enhancing the orientation growth of hetero-structure seeds with nanoparticles adsorbed thereon.
Figure 3 is a flow chart of the manufacturing process of the heterostructure seed of the present invention.
Figure 4 shows a scanning electron microscope (SEM) image and X-ray diffraction (XRD) measurement results of perovskite seeds manufactured by a topochemical molten-salt process.
Figure 5 shows the XRD measurement results of hetero-structure seeds adsorbed with (K,Na)NbO ₃ nanoparticles according to the change in the content of NaNbO ₃ seeds.
Figure 6 is a SEM image of a heterostructure seed with (K,Na)NbO ₃ nanoparticles adsorbed according to the change in the content of NaNbO ₃ seeds.
Figure 7 shows the XRD measurement results of hetero-structure seeds adsorbed with (K,Na)NbO ₃ nanoparticles according to changes in the BaTiO ₃ seed content.
Figure 8 is a SEM image of a heterostructure seed with (K,Na)NbO ₃ nanoparticles adsorbed according to changes in the BaTiO ₃ seed content.
Figure 9 is a conceptual diagram of the Templated Grain Growth (TGG) process.
Figure 10 shows the XRD measurement results of KNN oriented ceramics manufactured by changing the NaNbO ₃ seed content.
Figure 11 shows the XRD measurement results of KNN oriented ceramics manufactured using NaNbO ₃ based heterostructure seeds.
Figure 12 shows the change in density and d ₃₃ of oriented ceramics according to the content of conventional seeds and hetero-structure seeds of the present invention.

The above-mentioned objects, features and advantages will be described in detail below with reference to the attached drawings, so that those with ordinary skill in the art to which the present invention pertains can easily practice the technical idea of the present invention. In describing the present invention, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Hereinafter, the phrase “any configuration is disposed on (or below)” a component or “on (or below)” a component may mean not only that any configuration is disposed in contact with the upper surface (or lower surface) of said component, but also that another configuration may be interposed between said component and any configuration disposed on (or below) said component.

Additionally, when a component is described as being "connected,""coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected,""coupled," or "connected" through other components.

Hereinafter, perovskite seeds and their manufacturing methods according to some embodiments of the present invention will be described.

Figure 1 is a schematic diagram of a topochemical molten-salt process.

As illustrated in Fig. 1, the topochemical molten salt process is a process in which a two-dimensional intermediate is first created, the intermediate is mixed with a reaction powder and a salt, the temperature is raised above the melting point of the salt to create a liquid phase, and the intermediate is then converted into a perovskite structure through substitution or removal between component elements within the liquid phase.

The above-mentioned topochemical molten salt process is a process method that can change the composition while maintaining the shape of an intermediate.

The reason for using the above-mentioned topochemical molten salt process in the production of perovskite seeds is that the intermediate has a layered structure, which is advantageous in terms of thermodynamics for having a two-dimensional shape.

For the above reasons, seeds with perovskite structures of various compositions such as BaTiO ₃ (BT), NaNbO ₃ (NN), and PbTiO ₃ can be manufactured using the topochemical molten salt process.

In the present invention, when nanoparticles are uniformly adsorbed onto the surface of a seed manufactured through the topochemical molten salt process (hereinafter, a seed having nanoparticles uniformly adsorbed onto its surface is referred to as a heterostructure seed) and used as a seed in subsequent TGG (Templated Grain Growth), it was confirmed that the orientation and piezoelectric properties of piezoelectric ceramics can be improved compared to when a general seed is used that does not have nanoparticles adsorbed onto its surface.

Figure 2 illustrates the mechanism for enhancing the orientation growth of hetero-structure seeds with nanoparticles adsorbed thereon.

Conventional seeds without nanoparticle adsorption suffer from lattice mismatch during the subsequent TGG (Templated Grain Growth) process due to differences in composition between the seed and the ceramic matrix, resulting in deteriorated orientation and poor piezoelectric properties of the final product, the piezoelectric ceramics.

On the other hand, in the heterostructure seed in which the nanoparticles are adsorbed in the present invention, the nanoparticles can act as a kind of buffer layer that offsets the lattice mismatch between the seed and the ceramic matrix during the subsequent TGG (Templated Grain Growth) process. As a result, the piezoelectric ceramics according to the present invention can have improved piezoelectric properties along with the piezoelectric orientation.

Figure 3 is a flow chart of the manufacturing process of the heterostructure seed of the present invention.

As illustrated in FIG. 3, the heterostructure seed of the present invention first includes a step of manufacturing a perovskite structure seed using a topochemical molten salt process.

In the heterostructure seed of the present invention, the perovskite structure seed that can be utilized may be of the BaTiO ₃ (BT), NaNbO ₃ (NN), (K,Na)NbO ₃ (hereinafter, KNN) system.

Among the above seeds, in the case of BaTiO ₃ (BT), it is manufactured by weighing and mixing powder containing Ba and powder containing Ti.

At this time, the Ba-containing compound of the BT seed can be BaCO ₃ , and the Ti-containing compound can be TiO ₂ .

Manufacturing BT seed using a topochemical molten salt process requires three steps.

First, it can be manufactured by a method including the step of weighing Bi ₂ O ₃ and TiO ₂ according to the composition ratio so that they react to become Bi ₄ Ti ₃ O ₁₂ , mixing them using KCl and NaCl salts, and then heat-treating them at 1130° C. for 4 to 10 hours.

In the next step, after removing the residual salt (the removal process can be performed by washing several times using DI water), the method can be manufactured by weighing Bi ₄ Ti ₃ O ₁₂ , BaCO ₃ , and TiO ₂ in a composition ratio to become BaBi ₄ Ti ₄ O ₁₅ , and then using BaCl ₂ and KCl as salts, performing a heat treatment at 1080° C. for 4 to 10 hours.

Finally, after removing the residual salt, BaTiO 3 seed can be manufactured by a method including the step of weighing BaBi ₄ Ti ₄ O ₁₅ and BaCO ₃ to obtain BaTiO ₃ in a composition ratio, mixing them with KCl and NaCl salts, and finally heat-treating _them at 950° C. for 4 to 10 hours.

Meanwhile, among the above seeds, in the case of NN, a powder containing Na and a powder containing Nb are weighed and mixed to produce it.

At this time, the Na-containing compound can be Na ₂ CO ₃ and the Nb-containing compound can be Nb ₂ O ₅ .

Manufacturing NN seeds using a topochemical molten salt process requires two steps.

In the first step, to prepare an intermediate of Bi _2.5 Na _3.5 Nb ₅ O _18, NaCO ₃ , Bi ₂ O ₃ , and Nb ₂ O ₅ are weighed according to the composition ratio, mixed with NaCl salt, and then heat-treated at 1125 ℃ for 2 to 10 hours.

Next, after a washing process to remove residual salts, Bi _2.5 Na _3.5 Nb ₅ O ₁₈ and Na ₂ CO ₃ are weighed according to the reaction formula, mixed with NaCl salt, and then heat-treated at 1000 ℃ for 2 to 10 hours to produce NaNbO ₃ seed.

Figure 4 shows a scanning electron microscope (SEM) image and X-ray diffraction (XRD) measurement results of perovskite seeds manufactured by a topochemical molten-salt process.

As shown in Fig. 4, it was confirmed that both NN and BT seeds manufactured in the first step of Fig. 3 had a layered shape and a perovskite crystal structure.

In order to control the content of KNN nanoparticles adsorbed on the surface of the heterostructure seed of the present invention, in one embodiment of the present invention, the KNN nanoparticle synthesis conditions were fixed, and the seed content of each of NN and BT initially included during the production of the heterostructure seed was controlled to a ratio of about 0.8 to 5.0 wt.%.

More specifically, the above NN, BT seeds were placed in a reactor, and KOH (29 g), NaOH (5.3 g), Nb ₂ O ₅ (1.5 g) as raw materials for adsorbing KNN nanoparticles were mixed with 15 ml of DI water and 45 ml of ethylene glycol, placed in the reactor, and then the reactor was reacted at 200 ℃ for 20 hours using a solvo-thermal synthesis method.

The synthesized heterostructure seeds were manufactured by washing them several times using water and ethanol in a centrifuge.

Specific examples of the heterogeneous structure seed of the present invention and its manufacturing method are as follows.

1. Seed production

Comparative Example 1: NaNbO ₃ (NN) seed production

As a Na-containing compound, Na ₂ CO ₃ , as a Nb-containing compound, Nb ₂ O _{5 ,} and as a Bi-containing compound, Bi ₂ O ₃ were used, and their weights were measured so that the molar ratios thereof were 1.75: 2.5: 1.25, mixed with NaCl salt, and then heat-treated at 1125° C. for 2 to 10 hours to produce an intermediate of Bi _2.5 Na _3.5 Nb ₅ O ₁₈ .

Next, after washing the residual salt using DI water, the intermediate Bi _2.5 Na _3.5 Nb ₅ O ₁₈ and Na ₂ CO ₃ were mixed in a molar ratio of 1:1.5, and then mixed with NaCl salt and heat-treated at 1000 ℃ for 2 to 10 hours. After this, the residual salt was removed using DI water, and NaNbO ₃ seed was manufactured.

Comparative Example 2: BaTiO ₃ (BT) seed manufacturing

Bi ₂ O ₃ as a Bi-containing compound and TiO ₂ as a Ti-containing compound were mixed in a molar ratio of 2:3, and then KCl and NaCl salts were mixed in a 1:1 ratio and heat-treated at 1130° C. for 2 to 10 hours to produce Bi ₄ Ti ₃ O ₁₂ .

Then, Bi ₄ Ti ₃ O ₁₂ , BaCO ₃ , and TiO ₂ were weighed in a molar ratio of 1:1:1, then BaCl ₂ and KCl salt were mixed in a weight ratio of 1:1, and then heat-treated at 1080 ℃ for 2 to 10 hours to produce BaBi ₄ Ti ₄ O ₁₅ .

Finally, BaBi ₄ Ti ₄ O ₁₅ and BaCO ₃ were weighed in a molar ratio of 1:1, and then KCl and NaCl salts were weighed in a weight ratio of 4:1, mixed together, and heat-treated at 950 ℃ for 2 to 10 hours to produce BaTiO ₃ seeds.

Example 1: (K,Na)NbO ₃ NaNbO with nanoparticle adsorption ₃ (NN) Manufacturing of heterogeneous seed structures

In order to adsorb KNN nanoparticles onto NN seeds, raw material powders of nanoparticles (KOH (29 g), NaOH (5.3 g), Nb ₂ O ₅ (1.5 g)) were dissolved in 15 ml of DI water and 45 ml of ethylene glycol, and then mixed with approximately 0.8 to 5 wt% of NN seeds based on the total weight of the nanoparticles and seeds, and then placed in a reactor and reacted at 200 °C for 20 hours.

Afterwards, the seeds were washed with water and ethanol to prepare heterostructured seeds in which KNN nanoparticles were adsorbed on NaNbO ₃ seeds.

Example 2: (K,Na)NbO ₃ BaTiO with nanoparticle adsorption ₃ (BT) Manufacturing of heterogeneous seed structures

A heterostructure seed in which KNN nanoparticles were adsorbed on a BaTiO3 seed was prepared through the same process as in Example 1, except that BaTiO ₃ seed was used instead of NaNbO3 seed.

2. Property evaluation method and its results

Figure 5 shows the XRD measurement results of hetero-structure seeds adsorbed with (K,Na)NbO ₃ nanoparticles according to the change in the content of NaNbO ₃ seeds.

Figure 6 is a SEM image of a heterostructure seed with (K,Na)NbO ₃ nanoparticles adsorbed according to the change in the content of NaNbO ₃ seeds.

The XRD measurement results in Fig. 5 show that as the content of NaNbO ₃ (NN) seeds increases from 0.8 → 2.2 → 4.3 wt.%, the peak of the nanoparticles in the heterostructure seed in which (K,Na)NbO ₃ (KNN) nanoparticles are adsorbed on NN tends to decrease.

In other words, the XRD measurement results of Fig. 5 mean that as the content of NN seeds increases from 0.8 → 2.2 → 4.3 wt.%, the number of KNN nanoparticles adsorbed on the surface of the NN seeds decreases, and the XRD measurement results of Fig. 5 are also consistent with the tendency of nanoparticles adsorbed on the surface of the heterogeneous structure seeds observed in the SEM image of Fig. 6.

Figure 7 shows the XRD measurement results of heterostructure seeds adsorbed with (K,Na)NbO ₃ (KNN) nanoparticles according to changes in the BaTiO ₃ (BT) seed content.

Figure 8 is a SEM image of a heterostructure seed with (K,Na)NbO ₃ (KNN) nanoparticles adsorbed according to changes in the BaTiO ₃ (BT) seed content.

Similar to the XRD measurement results in Fig. 5, the XRD measurement results in Fig. 7 also show that as the content of BT seeds increases from 1.6 → 4.7 wt.%, the peak of the nanoparticles in the heterostructure seed in which KNN nanoparticles are adsorbed on BT tends to decrease.

In other words, the XRD measurement results of Fig. 7 mean that as the content of BT seeds increases from 1.6 → 4.7 wt.%, the number of KNN nanoparticles adsorbed on the surface of the BT seeds decreases, and the XRD measurement results of Fig. 7 are also consistent with the tendency of nanoparticles adsorbed on the surface of the heterogeneous structure seeds observed in the SEM image of Fig. 8.

Figure 9 is a conceptual diagram of the Templated Grain Growth (TGG) process.

The TGG process is a method of aligning grains by adding seeds in an anisotropic shape (mainly a flat plate shape, template), as shown in Fig. 9.

Specifically, first, a slurry is prepared by mixing a ceramic matrix (base, KNN ceramic in the present invention) powder of a composition to be manufactured and a seed.

Next, when a green sheet is manufactured by tape casting, the flat seeds included in the slurry are subjected to shear stress as they pass through the gaps of the blades, and are distributed in a uniformly lying form parallel to the surface of the green sheet, and the base powder is positioned between the seeds.

The green sheets manufactured by the above tape casting are cut and then laminated to form a molded body.

The above-mentioned molded body can be manufactured into an oriented-growth sintered body, which is the final product, by causing the base powder to be oriented and grown along the seed through a subsequent sintering process.

It is necessary to first manufacture a molded body in which two-dimensional seeds are uniformly distributed in a lying down form and matrix powder is positioned between them. To this end, tape casting is used to produce a tape shape, which is then cut and laminated to produce a molded body. Then, sintering is performed to allow the matrix powder to grow along the seeds in an oriented manner, thereby manufacturing an oriented-growth sintered body.

Figure 10 shows the XRD measurement results of KNN oriented ceramics manufactured by changing the content of NaNbO ₃ seed (corresponding to Comparative Example 1).

Figure 11 shows the XRD measurement results of KNN oriented ceramics manufactured using NaNbO ₃ based heterostructure seeds (corresponding to Example 1).

First, as shown in Fig. 10, when only the NaNbO ₃ seed (i.e., the seed that does not adsorb KNN nanoparticles on the seed surface) of Comparative Example 1 is used and the TGG process is performed together with the KNN matrix powder, it can be seen that as the seed content increases, the Lotgering factor (LF) increases, resulting in better oriented growth.

On the other hand, as shown in Fig. 11, when the NaNbO _3- based heterostructure seed of Example 1 of the present invention is used and the TGG process is performed together with the KNN matrix powder, it can be seen that the KNN-oriented ceramic by the seed of Example 1 has a higher Lotgering factor (LF) value than the KNN-oriented ceramic by the seed of Comparative Example 1 under the same seed content conditions.

The above orientation factor, i.e., the Lottering factor (LF), can be defined by the following equation.

The Lotgering factor (LF) can be expressed as F(00l) in the above equation, and is calculated based on X-ray diffraction data to determine how much the sample is oriented in the (00l) direction.

In the above formula, Po can be said to be a randomly existing powder XRD result, where the denominator represents the sum of the intensities of XRD peaks measured on all hkl planes, and the numerator represents the sum of the peak intensities of the (00l) plane among them (e.g., 001, 002, 003, etc.).

In other words, Po refers to how much the (001) plane appears in the X-ray diffraction data of a randomly existing powder compared to the sum of the intensities of all planes, and the value of Po serves as a reference value.

If the sample is randomly oriented (i.e., unoriented), then P = Po will be calculated, and F001 will have a value of 0 because the numerator becomes zero according to the above formula.

On the other hand, if all samples observe only the (001) peak and the P value is 1, F001 = 1 (100%) is calculated.

Ultimately, regardless of whether the sample is a seed or an oriented ceramic, measuring the LF value provides an indication of the degree of orientation in the (001) direction of the sample.

The results in Figures 10 and 11 directly demonstrate that the heterostructure seed of the present invention is superior (increased LF value) to the conventional seed in the orientation growth of KNN-oriented ceramics.

Figure 12 shows the change in density and piezoelectric constant (d ₃₃ ) of oriented ceramics according to the content of conventional seeds and heterostructure seeds of the present invention.

When comparing the piezoelectric properties of the manufactured orientation ceramics, it was confirmed that when the seed content is the same, the case using the heterostructure seed of the present invention shows a higher piezoelectric constant (d ₃₃ ) value than when using the conventional NN seed.

However, when the seed content increases from 6 to 10 wt%, it was measured that the piezoelectric properties decrease somewhat in both the case of utilizing the heterostructure seed of the present invention and the case of utilizing the conventional NN seed.

This is because both the heterostructure seed in the above-described embodiment of the present invention and the conventional NN seed have very low piezoelectric properties, so even if the orientation slightly increases when the seed content increases, the piezoelectric properties of the oriented ceramic decrease due to the low piezoelectric properties of the seed itself.

Meanwhile, from the results of FIGS. 10 and 12, it can be seen that the KNN ceramic manufactured using the NaNbO ₃ seed (i.e., the seed that does not adsorb KNN nanoparticles on the seed surface) in Comparative Example 1 does not have an LF value indicating the degree of orientation exceeding 91% even if the seed content is 10% or more. Furthermore, it was confirmed that the piezoelectric constant (d ₃₃ ) value of the final KNN ceramic is also 130 or less at most.

On the other hand, from the results of FIGS. 11 and 12, it was measured that the KNN ceramic manufactured using the NaNbO ₃ based heterostructure seed in Example 1 of the present invention had a high orientation degree of 92% or higher based on the LF value, which could not be achieved in the comparative example, when the seed content was 6% or higher. Furthermore, it was confirmed that the piezoelectric constant (d ₃₃ ) value of the final KNN ceramic could stably secure 150 or higher.

Although the present invention has been described with reference to the drawings as examples, it is obvious that the present invention is not limited to the embodiments and drawings disclosed in this specification, and that various modifications can be made by those skilled in the art within the scope of the technical idea of the present invention. In addition, even if the effects according to the configuration of the present invention were not explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be recognized.

Claims (11)

delete delete delete delete (a) a step of manufacturing a seed having a perovskite (ABO ₃ ) structure;
(b) a step of mixing the perovskite seed and raw material powder for nanoparticles and then performing solvo-thermal synthesis;
(c) a step of washing a heterostructure seed including nanoparticles having a composition of (K,Na)NbO ₃ (KNN) adsorbed on the seed surface of the perovskite structure formed in the synthesizing step (b);
A method for producing a heterostructure seed comprising:
In paragraph 5,
A manufacturing method in which the seed of the perovskite structure manufactured in the step (a) above includes at least one of BaTiO ₃ (BT), (K,Na)NbO ₃ (KNN), and NaNbO ₃ (NN).
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