KR20090126455A - Manufacturing method of pblatio3 nano powder - Google Patents

Abstract

PURPOSE: A method for manufacturing a lead lanthanum titanium oxide (PbLaTiO3)-based nanopowder is provided to obtain the PbLaTiO3-based nanopowder of the perovskite structure having fine and uniform spherical shape. CONSTITUTION: A method for manufacturing a PbLaTiO3-based nanopowder comprises the steps of weighing an oxide powder including a Pb component, an oxide powder including a La component and an oxide powder including a Ti component according to the desired composition of Pb_x La_(1-x) TiO3 (wherein x is a number greater than 0); and milling the oxide powders in a mechanical chemical mill provided with balls performing the linear motion and the reciprocating motion of 8 shape or lied 8 shape, to form the Pb_x La_(1-x) TiO3 nanoparticle having the perovskite structure.

Description

Manufacturing method of leadlanthanum titanium oxide-based nanopowder {Manufacturing method of PbLaTiO3 nano powder}

The present invention relates to a method for producing PLT powder, and more particularly, lead (Pb) component is not volatilized to obtain a target composition ratio and fine by mechanical chemical process from the oxide raw material powder without the calcination process and drying process And a method for producing a PbLaTiO ₃ -based nanopowder having a perovskite structure having a uniform spherical particle shape.

Conventional PLT powders have been prepared using chemical methods such as solid phase reaction, sol-gel method and hydrothermal reaction. The production of PLT powder using the solid-phase reaction method is performed in a general ball mill by mixing the oxides as raw materials in proportion, and then a relatively high temperature (eg, 600 to 800 ° C.) to obtain a pure perovskite crystal structure. Calcination process is necessary because it goes through the process of calcination at). The chemical method also requires a process of chemically treating the raw material oxide, followed by calcination.

In addition, in the case of ball milling using a solid-phase reaction method, a wet process in which a powder and a solution are put at the same time and milled is often used. At this time, since the drying process is added to obtain the powder after the milling is completed, it takes a long time. In addition, due to the high volatility of the lead (Pb) component during the calcination process, the loss of lead (Pb) component occurs, it is difficult to obtain the target composition, and as a result, there is a concern that the electrical characteristics are reduced. In addition, volatilized lead (Pb) may cause environmental pollution.

The technical problem to be achieved by the present invention is that the lead (Pb) component is not volatilized to obtain the desired composition ratio and fine and uniform spherical particle shape from the oxide raw material powder by the mechanical chemical process without the need for calcination process and drying process It is to provide a method for producing a PbLaTiO ₃ -based nanopowder having a perovskite structure.

The present invention includes an oxide powder containing a Pb component, an oxide powder containing a La component, and a Ti component such that a target composition of Pb _x La _{1 - x} TiO ₃ (x is a real number larger than 0) to be obtained. Oxide powders are weighed and milled by inserting the oxide powders into a mechanochemical process mill equipped with balls inside a vial that reciprocates in a linear or '8' or '∞' fashion. A method of preparing a PbLaTiO ₃ -based nanopowder to form nano-sized Pb _x La _{1 - x} TiO ₃ particles having a crystal structure.

In the method of manufacturing PbLaTiO ₃ -based nanopowder, the size of the ball, the weight ratio of the ball and the total oxide powder, the time required for the milling and the milling cycle rate of the vial may be adjusted by adjusting any one or more selected.

PbO powder may be used as the oxide powder including the Pb component, La ₂ O ₃ powder may be used as the oxide powder including the La component, and TiO ₂ powder may be used as the oxide powder including the Ti component.

The milling is preferably carried out for 1 to 24 hours.

The cycle rate per minute of the vial is preferably set in the range of 800 to 1200 cycles / min.

It is preferable that the said balls and all the oxide powders are 10-30: 1 by weight ratio.

According to the present invention, PLT nanopowders may be synthesized using a Mechano Chemical Process (MCP), and the particles of the PLT nanopowders have a fine size and have a uniform spherical particle shape.

By using the chemical chemical process, the pure perovskite crystal structure can be obtained at room temperature because the phase formation reaction is activated by mechanical energy. This high-energy mechanochemical milling process enables the synthesis of nano-sized PLT powder directly from oxide raw powders without calcination at high temperatures. The solid-solution reaction is performed only by using a mechanical chemical process using an oxide powder that is hardly chemically formed, and a new phase is formed and manufactured into a nano-sized powder. Since the phase formation is activated by mechanical energy, no separate calcination process is required.

In addition, since the PLT phase is formed by the solid-solid reaction at a relatively low temperature without the calcination process at a high temperature, the lead (Pb) component is not volatilized to obtain a target PLT composition ratio.

In addition, unlike the wet process, the dry process does not require a separate powder drying process, so the manufacturing process is simple and cost-effective.

Further, according to the present invention, a pure perovskite phase can be formed regardless of the purity of the raw material oxide powder.

In addition, compared to the conventional solid-state reaction, sol-gel method and hydrothermal reaction, compared to chemical methods, the manufacturing process is relatively simple and mass production is possible, and thus many fields including piezoelectric materials, nonvolatile memory, sensors, actuators, etc. It can be used effectively.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen.

The present invention is a Pb _x La _{1 - x} TiO ₃ (x is 0) having a nano-sized perovskite structure directly in the oxide raw powder using a Mechanochemical process (hereinafter referred to as 'MCP') Larger real number) (hereinafter referred to as 'PLT'). Unlike the wet process, the dry process does not require a separate powder drying process, which makes the manufacturing process simple and cost effective, and does not require a calcination process at high temperatures. Pb _x La _{1 - x} TiO ₃ (x is a real number greater than 0) nanoparticles can be synthesized.

1 is a view showing an MCP mill, 'A' of FIG. 1 is a view showing for explaining the operation of the vial 10 mounted on the MCP mill. MCP mills are also called vibrational shake mills. Unlike the simple circular motion of the conventional milling equipment, the machine rotates the axis in the form of '8' or '∞' and moves up and down and left and right as shown in FIG. 1 as the vial 10 vibrates as it moves. Seems to do. Such movement of the vial 10 is driven by a drive means such as a motor. The vial 10 may have various shapes, and preferably, a cylindrical shape is preferable in terms of linear motion and reciprocating motion of a '8' or '∞' type. After the ball and the oxide powder is charged in the baal 10 and the charging port is sealed with a lid, a mechanical chemical process is performed using mechanical energy caused by the movement of the vial.

In the vial 10 moving in the above-described form, the collision of the ball and the ball, the collision of the ball and the vial occurs a lot, so that a lot of mechanical energy is generated inside the vial (10). The generated mechanical energy causes the activation of the mixed oxide powder to cause a chemical reaction between the oxides to produce PLT nanopowders.

PLT having a perovskite structure directly from raw oxide (PbO, La ₂ O ₃ , TiO ₂ ) powder by mechanical energy using a mechanochemical process (MCP) without carrying out calcination at high temperatures Nano powder can be synthesized.

At this time, high purity powders and low purity powders were used as the oxide powders, and as the milling time passed, all of them showed pure perovsktie structures regardless of the purity. This can be confirmed from Example 1 and Example 2.

Hereinafter, a method for preparing PLT nano powder having a perovskite structure using a mechanical chemical process will be described.

The method for producing a PLT nanopowder having a perovskite structure according to a preferred embodiment of the present invention includes each component (Pb, La, Ti) of Pb _x La _{1 - x} TiO ₃ (x is a real number larger than 0). The oxide powders to be mixed are mixed so as to obtain a target composition of Pb _x La _{1 - x} TiO ₃ (x is a real number larger than 0) powder. PbO may be used as an oxide including a lead (Pb) component, La ₂ O ₃ may be used as an oxide including a lanthanum (La) component, and TiO ₂ may be used as an oxide including a titanium (Ti) component. Can be used.

It is loaded into an MCP mill to uniformly mix oxide powders containing each component of Pb _x La _{1 - x} TiO ₃ (x is a real number greater than zero). Using an MCP mill, oxide powders containing each component of the ball and Pb _x La _1-x TiO ₃ (x is a real number greater than 0) are placed in the vial of the MCP mill and the vial is vibrated at a constant speed to produce Pb _x La _{1 - x} TiO ₃ is pulverized in the oxide powder comprising the components of (x is a real number greater than 0) to mechanochemical and uniformly mixed. At this time, the temperature rises due to the collision of the ball and the powder, the ball and the ball, the ball and the vial, and a solid-solid reaction occurs between the raw material oxides. During the MCP process, oxides react with each other due to temperature rise and collision energy.

The ball used in the MCP mill may use a ball made of ceramic or metal such as alumina or zirconia, and the balls may be all the same size or may be used together with two or more balls.

The size of the ball, the weight ratio of the ball and the oxide powder, the mechanical chemical process time, the cycle rate per minute (cylces / min) of the vial 10 of the MCP mill, etc. are adjusted to grind to the size of the target particles. For example, considering the particle size, the size of the ball is set in the range of about 1 mm to 10 mm, and the cycle speed per minute of the vial reciprocating in a linear motion and '8' or '∞' type is 800 to 1200. It can be set within the range of cycles / min. The mechanochemical process (MCP) is carried out for 1 to 24 hours in consideration of the target particle size and the degree of solid phase reaction. If the mechanical chemical process time is less than 1 hour, the raw oxide powder may remain in addition to the PLT phase, and even if the mechanical chemical process time exceeds 24 hours, the particle size of the PLT nano powder is reduced so that the particle size is further reduced. There is a limit and it is not economic. It is preferable that the ball and the total raw material oxide powder introduced into the vial are about 10 to 30: 1 by weight. When the content of the balls in the raw material oxide powder is too small, there is a limitation in agglomeration of particles or miniaturization of the particles due to insufficient grinding, and is not efficient when the content of the balls in the raw material oxide powder is too large. .

When grinding with an MCP mill, the particle size decreases to less than submicrons in a short time, the direct contact area of the reaction particles increases, and the temperature rises due to the collision of the ball and powder, the ball and the ball, the ball and the vial. Solid-solid reactions occur. Therefore, no calcination step is required, and PLT nanopowders having a particle size of nanometer (nm) can be obtained. This is because the particles are uniformly distributed through the mechanochemical process (MCP) and the size of the powder particles becomes fine below the submicron to increase the direct contact area of the reaction particles. Submicron means a size smaller than 1 μm, and generally means a size in nanometers (nm) smaller than 1 μm, ie in the range of 1 nm to 1000 nm. By nanopowder is meant a powder having a particle size in the nanometer size, that is, in the range of 1 nm to 1000 nm. By MCP, the source raw material oxides of each component of the PLT are ground to fine-sized particles, have a uniform particle size distribution, are mixed evenly, and mechanical polishing by a ball and solid-solid reaction in an MCP mill. By chemical action occurs at the same time will be a mechanical chemical treatment.

The invention is described in more detail with reference to the following examples, which are not intended to limit the invention.

<Example 1>

PbO, La ₂ O ₃ and TiO ₂ were used as oxides containing each component of PLT. At this time, PbO was used as Aldrich Chemical powder of 99.99% high purity, La ₂ O ₃ was used as Aldrich Chemical powder of 99.99% high purity, TiO ₂ was 99.99%. Powder of Cosmo Chemical Co., Ltd. having a high purity of was used. Figure 2 is a field emission scanning electron microscope (Field Emission Scanning Electron Microscopy (hereinafter 'FE-SEM') (200kV, Hitachi, Japan) photograph of the used PbO powder, Figure 3 is a photograph of the used La ₂ O ₃ powder FE-SEM picture, Figure 4 is a FE-SEM picture of the TiO ₂ powder used. FIG. 5 is a graph showing XRD profiles of crystal structures and compositions using X-ray diffraction (XRD) (CuKα, Rigaku, Japan) of PbO, La ₂ O ₃ and TiO ₂ powders. to be.

After weighing the ratio of PbO: La ₂ O ₃ : TiO ₂ to a molar ratio of 0.9: 0.05: 1, a mechanical chemical process was performed for 0 to 12 hours by a dry method using an MCP mill. SPEX mill 800M-115 from SPEX was used as an experimental equipment for carrying out the mechanical chemical process (MCP). In this case, zirconia (ZrO ₂ ) ball was used, and two types of balls having a size of 10 mm and 5 mm were used together as the particle size of the ball. The zirconia balls used were added in a weight ratio (wt%) of about 18: 1 (18: 1 weight ratio of zirconia ball: mixed powder) to the weight of the mixed powder of PbO, La ₂ O ₃ and TiO ₂ . The cycle speeds per minute of the vials reciprocating in linear and '8' or '∞' form were set to 1050 cycles / min.

FE-SEM images of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanical chemical process time are shown in FIGS. 6A to 6E. FIG. 6A is a FE-SEM photograph after mixing PbO, La ₂ O ₃ and TiO ₂ powders (mechanical chemical process 0 hours), and FIG. 6B is 30 minutes for PbO, La ₂ O ₃ and TiO ₂ mixed powders (FIG. 0.5 hr) FE-SEM photographs when the mechanical chemical process was performed, Figure 6c is a FE-SEM photographs when the mechanical chemistry process for 1 hour (1 hr) for PbO, La ₂ O ₃ and TiO ₂ mixed powder 6d is a FE-SEM photograph of a mechanical chemical process performed for 4 hours (4hr) on PbO, La ₂ O _3, and TiO ₂ mixed powder, and FIG. 6e is a mixture of PbO, La ₂ O _3, and TiO _2. It is FE-SEM photograph when the mechanical chemical process was performed for 12 hours (12hr) with respect to the powder. Figure 7 is a graph showing the XRD profile of PbO, La ₂ O ₃ and TiO ₂ mixed powder with the time of the mechanical chemical process. As shown in Figure 6a to 7, after about 30 minutes after the start of the mechanical chemical process, the particles are finely pulverized to form a spherical powder, and after about 1 hour after the start of the mechanical chemical process solid-solid It can be seen that PLT nano powder having a perovskite structure was obtained by the reaction. It can be seen from FIGS. 6A to 7 that the particle size of the powder decreases and has a uniform distribution as the time of the mechanical chemical process increases. In addition, it can be seen from FIG. 7 that the PbO decreases as the mechanical chemical process time increases, and that a pure PLT phase is formed when the mechanical chemical process time reaches 1 hour or more.

<Example 2>

Using the same components as in Example 1 to prepare a PLT nano powder in the same manner, PbO was used powder of Danseok Industrial Co., Ltd. having a purity of 99.5%, La ₂ O ₃ Leeyoung Ceracam Co. having a purity of 99.7% Powder of TiO ₂ was used, and powder of Cosmo Chemical Co., Ltd. having a purity of 98% was used. Figure 8 is a FE-SEM picture of the PbO powder used, Figure 9 is a FE-SEM picture of the La ₂ O ₃ powder used, Figure 10 is a FE-SEM picture of the TiO ₂ powder used. FIG. 11 is a graph showing XRD profiles of crystal structures and compositions using X-ray diffractometers (XRD) of PbO, La ₂ O _3, and TiO ₂ powders.

After weighing the ratio of PbO: La ₂ O ₃ : TiO ₂ to a molar ratio of 0.9: 0.05: 1, a mechanical chemical process was performed for 0 to 12 hours by a dry method using an MCP mill. SPEX mill 800M-115 from SPEX was used as an experimental equipment for carrying out the mechanical chemical process (MCP). In this case, zirconia (ZrO ₂ ) ball was used, and two types of balls having a size of 10 mm and 5 mm were used together as the particle size of the ball. The zirconia balls used were added in a weight ratio (wt%) of about 18: 1 (18: 1 weight ratio of zirconia ball: mixed powder) to the weight of the mixed powder of PbO, La ₂ O ₃ and TiO ₂ . The cycle speeds per minute of the vials reciprocating in linear and '8' or '∞' form were set to 1050 cycles / min.

FE-SEM images of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanical chemical process time are shown in FIGS. 12A to 12E. 12a is a FE-SEM photograph after mixing PbO, La ₂ O ₃ and TiO ₂ powder (mechanical chemical process 0 hours), FIG. 12b is 1 hour for PbO, La ₂ O ₃ and TiO ₂ mixed powder (FIG. 1 hr) FE-SEM photographs when the mechanical chemical process was performed, Figure 12c is a FE-SEM photographs when the mechanical chemistry process for 2 hours (2hr) for PbO, La ₂ O ₃ and TiO ₂ mixed powder , Figure 12d is PbO, La ₂ O ₃ and TiO ₂ is FE-SEM picture of the case subjected to mechanical chemical process for 4 hours (4hr) with respect to the mixed powder, Fig. 12e is PbO, La ₂ O ₃ and TiO ₂ powder mixture This is a FE-SEM photograph when the mechanical chemical process was performed for 12 hours (12hr). FIG. 13 is a graph showing an XRD profile of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanical chemical process time. As shown in Figure 12a to Figure 13, after about 1 hour after the start of the mechanical chemical process, the particles are finely pulverized to form a spherical powder, after about 4 hours after the start of the chemical chemical process solid-solid It can be seen that PLT nano powder having a perovskite structure was obtained by the reaction. It can be seen from FIGS. 12a to 13 that the particle size of the powder decreases and has a uniform distribution as the mechanical chemical process time increases. In addition, it can be seen from FIG. 13 that the PbO decreases as the mechanical chemical process time increases, and that a pure PLT phase is formed when the mechanical chemical process time reaches 4 hours or more.

PLT nanopowders of the perovskite structure were molded and sintered using the manufactured perovskite structure PLT nanopowders, and then sintering characteristics were examined.

PLT nano powder, which was subjected to a mechanical chemical process for 4 hours according to Example 2, was molded into a disk type having a diameter of 10 mm by applying a uniaxial pressure of 300 MPa using an auto press (Carver, USA), Charged into an electric furnace and sintered for 3 hours at 1050 ℃ Air (air) atmosphere to obtain a PLT dielectric. FIG. 14A is an FE-SEM photograph of a PLT dielectric surface sintered at a temperature of 1050 ° C., and FIG. 14B is an FE-SEM photograph of a PLT dielectric cross section sintered at a temperature of 1050 ° C.

PLT nano powder, which was subjected to a mechanical chemical process for 4 hours according to Example 2, was molded into a disk type having a diameter of 10 mm by applying a uniaxial pressure of 300 MPa using an auto press (Carver, USA), Charged into an electric furnace and sintered for 3 hours at 1150 ℃ Air (Air) atmosphere to obtain a PLT dielectric. FIG. 15A is an FE-SEM photograph of a PLT dielectric surface sintered at a temperature of 1150 ° C., and FIG. 15B is an FE-SEM photograph of a PLT dielectric cross section sintered at a temperature of 1150 ° C.

In Table 1 below Pb _{0 .9} La _{0 .1} TiO ₃ shows the characteristics of the sintering of the nano-powder.

Sintering Temperature Theoretical density (g / cm3) Weight loss (%) Density measured by Archimedes method Relative density 1050 ℃ 7.77 2.52 7.29 93.8 1150 ℃ 7.77 3.57 7.44 95.8

It is generally known that sintering of PLT takes place at 1200 ° C or higher. The nanopowders prepared according to the invention were fully densified at 1150 ° C. and also showed a good relative density of 94% even at low temperatures of 1050 ° C. Due to the small particle size of several tens of nanometers of PLT nanopowder produced by MCP milling, the grain boundary contact area is increased, the driving force of sintering is increased, and the material movement distance for sintering is shortened, resulting in sintering at low temperature. Done

As shown in FIGS. 14A-15B and Table 1, a complete PLT dielectric phase has been formed, and it can be seen that grain size increases with increasing sintering temperature.

FIG. 16 is a graph showing an XRD profile of a PLT dielectric formed by sintering at 1050 ° C. and 1150 ° C. for 3 hours. As shown in FIG. 16, it can be seen that a complete PLT dielectric phase was formed and no phase separation phenomenon was observed.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

1 shows an MCP mill.

2 is an FE-SEM photograph of PbO powder having 99.99% purity of Aldrich Chemicals.

3 is an FE-SEM photograph of La ₂ O ₃ powder having 99.99% purity of Aldrich Chemicals.

4 is a FE-SEM photograph of TiO ₂ powder having a 99.99% purity of Cosmo Chemical Co., Ltd.

FIG. 5 is a graph showing an XRD profile confirming crystal structure and composition using an X-ray diffractometer of PbO, La ₂ O ₃ and TiO ₂ powders.

6A through 6E are FE-SEM photographs of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanochemical process time.

Figure 7 is a graph showing the XRD profile of PbO, La ₂ O ₃ and TiO ₂ mixed powder with the time of the mechanical chemical process.

8 is an FE-SEM photograph of PbO powder having a purity of 99.5% of Danseok Industrial Co., Ltd.

9 is a FE-SEM photograph of La ₂ O ₃ powder having a purity of 99.7% of Lee Young Ceracam.

10 is a FE-SEM photograph of a TiO ₂ powder having a purity of 98% of Cosmo Chemical Co., Ltd.

FIG. 11 is a graph showing an XRD profile confirming crystal structure and composition by X-ray diffractometer of PbO, La ₂ O ₃ and TiO ₂ powder.

12A to 12E are FE-SEM photographs of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanochemical process time.

FIG. 13 is a graph showing an XRD profile of PbO, La ₂ O ₃ and TiO ₂ mixed powders according to the mechanical chemical process time.

FIG. 14A is a FE-SEM photograph of a PLT dielectric surface sintered at a temperature of 1050 ° C., and FIG. 14B is a FE-SEM photograph of a PLT dielectric cross section sintered at a temperature of 1050 ° C. FIG.

FIG. 15A is a FE-SEM photograph of a PLT dielectric surface sintered at a temperature of 1150 ° C., and FIG. 15B is a FE-SEM photograph of a PLT dielectric cross section sintered at a temperature of 1150 ° C.

FIG. 16 is a graph showing an XRD profile of a PLT dielectric formed by sintering at 1050 ° C. and 1150 ° C. for 3 hours.

Claims (6)

Weigh an oxide powder containing a Pb component, an oxide powder containing a La component, and an oxide powder containing a Ti component so as to obtain a target composition of Pb _x La _{1 - x} TiO ₃ (x is a real number larger than 0) to be obtained. And milling oxide powders in a mechanochemical process mill equipped with balls in a vial that reciprocates in a linear or '8' or '∞' shape to form a perovskite crystal structure. A method for producing a PbLaTiO ₃ -based nanopowder characterized in that to form a nano-sized Pb _x La _{1 - x} TiO ₃ particles having. According to claim 1, PbLaTiO ₃ system characterized in that the milling by adjusting any one or more selected from the size of the ball, the weight ratio of the ball and the total oxide powder, the time required for the milling and the cycle rate per minute of the vial. Method for preparing nano powder. According to claim 1, PbO powder as the oxide powder containing the Pb component, La ₂ O ₃ powder as the oxide powder containing the La component, TiO ₂ powder is used as the oxide powder containing the Ti component. Method for producing a PbLaTiO _3- based nanopowder characterized in that. The method for producing PbLaTiO ₃ -based nanopowders according to claim 1, wherein the milling is performed for 1 to 24 hours. According to claim 1, ₃ PbLaTiO-based method for producing nano-powder, characterized in that the per minute cycle rate of the vial is set in the range of 800~1200 cycles / min. The method of claim 1, wherein the ball and the total oxide powder is 10 to 30 in a weight ratio: ₃ PbLaTiO-based method for producing nano-powder according to claim 1.

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