KR20240133505A - Piezoelectric ceramics sintered body and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a piezoelectric ceramic sintered body and a method for manufacturing the same. The piezoelectric ceramic sintered body according to the present invention comprises a PNN-PMN-PZT ceramic composition of the following chemical formula 1 or a PZN-PMN-PZT ceramic composition of the following chemical formula 2; and antimony added thereto:
[Chemical Formula 1]
(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃
(0.01≤x≤0.13)
[Chemical formula 2]
(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃
(0.02≤y≤0.18, 0.50≤z≤0.55).

Description

Piezoelectric ceramic sintered body and manufacturing method thereof {PIEZOELECTRIC CERAMICS SINTERED BODY AND MANUFACTURING METHOD THEREOF}

The present invention relates to a piezoelectric ceramic sintered body and a method for manufacturing the same.

Piezoelectric vibrators made using piezoelectric ceramics have a simple structure, so they can be made miniaturized and lightweight, and their frequency band is very wide, so they can be used in various ways depending on the center frequency. Depending on the shape of the piezoelectric ceramic, such as cylinder, disk, or curved, the vibration mode can be used differently, and in the case of the disk type, there is an advantage of high power in the low frequency range due to the combination with metal, so demand is increasing.

In order to apply piezoelectric materials as ultrasonic vibrators, it is important to develop materials with high piezoelectric constants and conversion efficiency because the devices operate using elastic vibrations. In addition, it is essential to develop excellent piezoelectric materials that can simultaneously satisfy a high mechanical quality factor in order to reduce losses due to heat generation.

In order to improve the piezoelectric properties, research is actively being conducted to replace part of the PZT with a relaxor-type ferroelectric material by combining metal ions with different valences in the B-site of the perovskite structure of ABO ₃ based on the PZT composition. At this time, there is a problem that the metal ions substituted in the B-site react first to form a secondary phase such as a pyrochlore phase, which leads to a deterioration in the piezoelectric properties of the material, and therefore the development of a new material that can prevent the deterioration of the material properties is required.

The background technology described above is technology that the inventor possessed or acquired in the process of deriving the disclosure content of the present application, and cannot necessarily be said to be a publicly known technology disclosed to the general public prior to the present application.

In order to solve the above-described problem, the present invention aims to provide a piezoelectric ceramic sintered body having improved piezoelectric performance by adding antimony to a PZT series piezoelectric ceramic composition, and a method for manufacturing the same.

Specifically, the piezoelectric ceramic sintered body according to the present invention can prevent the deterioration of the material properties by adding antimony as a doping material after synthesizing a PZT composition, and provides a piezoelectric ceramic mix sintered body that can be utilized as a material for a piezoelectric vibrator.

However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the relevant technical field from the description below.

The piezoelectric ceramic sintered body according to the present invention comprises a PNN-PMN-PZT ceramic composition of the following chemical formula 1 or a PZN-PMN-PZT ceramic composition of the following chemical formula 2; and antimony added thereto;

[Chemical Formula 1]

(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃

(0.01≤x≤0.13)

[Chemical formula 2]

(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃

(0.02≤y≤0.18, 0.50≤z≤0.55).

According to one embodiment, the antimony may include at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).

In one embodiment, the antimony may be present in an amount of 0.05 wt% to 0.5 wt% of the piezoelectric ceramic sintered body.

In one embodiment, a curing agent is further added, and the curing agent may include at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and cobalt oxide (Co ₂ O ₃ ).

According to one embodiment, the piezoelectric ceramic sintered body may have a piezoelectric coefficient of 300 pC/N to 500 pC/N and a mechanical quality factor of 1000 to 1500.

In one embodiment, x may be from 0.05 to 0.10.

According to one embodiment, the piezoelectric ceramic sintered body may have a Curie temperature of 250° C. to 300° C.

In one embodiment, y may be from 0.05 to 0.10 and z may be from 0.50 to 0.52.

According to one embodiment, the piezoelectric ceramic sintered body may have a Curie temperature of 280° C. to 350° C.

A method for manufacturing a piezoelectric ceramic sintered body according to the present invention comprises the steps of: adding a first raw material powder containing PbO, ZrO ₂ , TiO ₂ , NiO, Nb ₂ O ₅ and MnO ₂ or a second raw material powder containing PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ and MnO ₂ to a solvent so as to have a composition formula of the following chemical formula 1 or the following chemical formula 2, and preparing a mixture by a wet mixing method; drying the mixture and then calcining it to form a first powder; adding antimony to the first powder and then drying it after wet mixing to form a second powder; and forming and sintering the second powder to form a piezoelectric body;

[Chemical Formula 1]

(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃

(0.01≤x≤0.13)

[Chemical formula 2]

(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃

(0.02≤y≤0.18, 0.50≤z≤0.55).

According to one embodiment, the step of preparing the mixture may be wet mixing the first raw material powder or the second raw material powder with at least one solvent selected from the group consisting of methanol, ethanol, isopropanol, and distilled water for 10 to 40 hours.

In one embodiment, the calcination may be performed at a temperature of 800° C. to 900° C.

According to one embodiment, the antimony may include at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).

In one embodiment, the sintering may be performed at a temperature of 900° C. to 1100° C. for 1 hour to 5 hours.

The present invention can provide a piezoelectric ceramic sintered body having improved piezoelectric performance by adding antimony to a PZT-based piezoelectric ceramic composition, and a method for manufacturing the same.

Specifically, the piezoelectric ceramic sintered body according to the present invention can provide a piezoelectric ceramic sintered body in which a PZT composition is synthesized by adding a relaxed ferroelectric material and then antimony is added as a doping material to prevent deterioration of the material properties. In order to be utilized as a material for a piezoelectric vibrator, it can exhibit a high piezoelectric coefficient and conversion efficiency as well as a high mechanical quality factor at the same time compared to existing commercialized materials, and it can enable the development of a new material without the addition of expensive rare elements.

FIG. 1 is a graph showing the results of measuring electrical characteristics of (a) a PNN-PMN-PZT sintered body and (b) a PZN-PMN-PZT sintered body according to the PMN content manufactured according to an embodiment of the present invention.
FIG. 2 is a graph showing the results of XRD analysis of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.
FIG. 3 is a SEM image of a PNN-PMN-PZT sintered body according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.
FIG. 4 is a graph showing the density measurement results of PNN-PMN-PZT sintered bodies according to the antimony trioxide (Sb ₂ O ₃ ) doping content manufactured according to an embodiment of the present invention.
FIG. 5 is a graph showing the results of measuring electrical characteristics of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.
FIG. 6 is _a graph showing the results of measuring dielectric properties according to temperature changes at 1 kHz of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the doping content of antimony _trioxide (Sb 2 O 3 ) manufactured according to an embodiment of the present invention.
FIG. 7 is a graph showing (a) the electrical property measurement results and (b) the dielectric property measurement results of PZN-PMN-PZT sintered bodies with different Ti contents manufactured according to an embodiment of the present invention.

Hereinafter, embodiments will be described in detail with reference to the attached drawings. However, since various modifications may be made to the embodiments, the scope of rights of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or substitutes to the embodiments are included in the scope of rights.

The terms used in the examples are for the purpose of description only and should not be construed as limiting. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, the terms "comprises" or "has" and the like are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood to not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Unless otherwise defined, 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 the embodiments belong. Terms defined in commonly used dictionaries, such as those defined in common dictionaries, should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and shall not be interpreted in an idealized or overly formal sense, unless expressly defined in this application.

In addition, when describing with reference to the attached drawings, regardless of the drawing number, the same components will be given the same reference numbers and redundant descriptions thereof will be omitted. When describing an embodiment, if it is determined that a specific description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted. In addition, when describing a component of an embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the component from other components, and the nature, order, or sequence of the component is not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

Components included in one embodiment and components including common functions will be described using the same names in other embodiments. Unless otherwise stated, descriptions given in one embodiment can be applied to other embodiments, and specific descriptions will be omitted to the extent of overlap.

The piezoelectric ceramic sintered body according to the present invention comprises a PNN-PMN-PZT ceramic composition of the following chemical formula 1 or a PZN-PMN-PZT ceramic composition of the following chemical formula 2; and antimony added thereto:

[Chemical Formula 1]

(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ (hereinafter referred to as "PNN-PMN-PZT") (0.01≤x≤0.13)

[Chemical formula 2]

(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ (hereinafter referred to as "PZN-PMN-PZT") (0.02≤y≤0.18, 0.50≤z≤0.55).

The piezoelectric ceramic sintered body of the present invention is a compound represented by PNN-PMN-PZT consisting of a (Pb, Ni, Nb)-(Pb, Mn, Nb)-(Pb, Zr, Ti) phase or a compound represented by PZN-PMN-PZT consisting of a (Pb, Zn, Nb)-(Pb, Mn, Nb)-(Pb, Zr, Ti) phase, to which antimony as a doping material is added, to form (0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ + W wt% antimony (0.01≤x≤0.13, 0.05<W<0.5) or (0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ + W wt% antimony (0.02≤y≤0.18, 0.50≤z≤0.55, 0.05<W<0.5).

PNN, PZN, and PMN are relaxor-type ferroelectric materials that can be simultaneously substituted for the PZT system. PNN or PZN acts as a soft relaxor, and PMN acts as a hard relaxor, and can exhibit excellent piezoelectric coefficient (d _-33 ) and mechanical quality factor (Q _m ).

A relaxorative ferroelectric material containing antimony can be formed as a ternary composition by substituting antimony in the PZT composition with the ABO ₃ structure (Pb(Sb, Nb)O ₃ ). In this case, the metal ions may first react with each other to form a secondary phase such as a pyrochlore phase, which may cause a deterioration in the piezoelectric properties of the material. The present _invention prevents the deterioration of the properties of the material and improves the piezoelectric performance by first synthesizing a PNN-PMN-PZT composition or a PZN-PMN-PZT composition and then adding a small amount of antimony as a doping material, rather than forming a Pb(B'B")O 3 composite perovskite compound through the substitution of antimony.

The piezoelectric ceramic sintered body according to the present invention is a 3-component piezoelectric ceramic composition, which is generally limited in application to energy conversion devices due to low dielectric constant and mechanical quality, and is configured as a 4-component system by controlling the composition ratio of the relaxor and additionally doping antimony, so that it has excellent temperature stability and phase transition, and thus can be used as an energy conversion device such as a piezoelectric vibrator.

According to one embodiment, the antimony may include at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).

Antimony, a doping material, can generate oxygen vacancies in the perovskite crystal by forming space charges as antimony ions occupy B-site sites with similar ionic radii and high valence, which can increase the mechanical quality factor (Q _m ) of the piezoelectric ceramic composition.

Preferably, the antimony may be antimony trioxide (Sb ₂ O ₃ ). Accordingly, the piezoelectric ceramic sintered body of the present invention is preferably (0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ + W wt% Sb ₂ O ₃ (0.01≤x≤0.13, 0.05<W<0.5) or (0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ + W wt% Sb ₂ O ₃ (0.02≤y≤0.18, 0.50≤z≤0.55, It can have a composition formula of 0.05<W<0.5).

In one embodiment, the antimony may be present in an amount of 0.05 wt% to 0.5 wt% of the piezoelectric ceramic sintered body.

The antimony may preferably be 0.05 wt% to 0.4 wt%, 0.1 wt% to 0.4 wt%, 0.1 wt% to 0.3 wt%, or 0.1 wt% to 0.2 wt% of the piezoelectric ceramic sintered body. When the content of antimony is less than 0.05 wt%, the effect of improving the mechanical quality factor (Q _m ) of the piezoelectric ceramic sintered body cannot be exhibited, and when it exceeds 0.5 wt%, more defects such as oxygen vacancies are generated inside the piezoelectric ceramic sintered body, which may affect a decrease in density and cause a problem of deterioration in the piezoelectric properties of the material.

In one embodiment, a curing agent is further added, and the curing agent may include at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and cobalt oxide (Co ₂ O ₃ ).

The above curing agent is used as a doping material, but is not limited thereto, and a material known as a curing agent for piezoelectric ceramic sintered bodies may be used.

The above-mentioned curing agent may be 0.1 wt% to 1.0 wt% of the piezoelectric ceramic sintered body. Preferably, it may be 0.1 wt% to 0.8 wt%, 0.3 wt% to 0.8 wt%, or 0.3 wt% to 0.6 wt%. When the curing agent is added within the above range, the mechanical quality factor (Q _m ) can be increased, and when it is out of the above range, the physical properties such as the electromechanical coupling factor (k _p ) may be deteriorated.

According to one embodiment, the piezoelectric ceramic sintered body may have a piezoelectric coefficient of 300 pC/N to 500 pC/N and a mechanical quality factor of 1000 to 1500.

The piezoelectric ceramic sintered body according to the present invention can be used as a piezoelectric vibrator, and in order to be applied as a vibrator, it is necessary to appropriately convert electrical energy into mechanical energy by using elastic vibration. Therefore, it is important to satisfy piezoelectric characteristics such as a high piezoelectric coefficient (d ₃₃ ), an electromechanical coupling coefficient (k _p ) for improving energy conversion efficiency, and a high mechanical quality factor (Q _m ) for reducing heat loss.

The above piezoelectric coefficient (d ₃₃ ) can be calculated using a d ₃₃ meter (Model YE2730, HANTECH, Gunpo, Korea), and the mechanical quality factor (Q _m ) can be calculated using an impedance analyzer (Model 4990A, Keysight Technologies Inc., Santa Rosa, CA, USA) according to the IEEE standard method.

The piezoelectric ceramic sintered body according to the present invention can exhibit a high piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) without deterioration of piezoelectric properties by substituting a relaxor-type ferroelectric material in an appropriate composition ratio in a PZT composition and additionally doping antimony. When the piezoelectric coefficient (d ₃₃ ) and the mechanical quality factor (Q _m ) are within the above ranges, both the piezoelectric coefficient and the mechanical quality factor exhibit excellent values, while reducing energy conversion efficiency and heat loss, thereby maintaining excellent piezoelectric properties and exhibiting characteristic values suitable as a material for a high-efficiency vibrator.

In one embodiment, x may be from 0.05 to 0.10.

(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ + W wt% antimony (0.01≤x≤0.13, 0.05<W<0.5) In the composition formula, x may be 0.01 to 0.12; 0.03 to 0.12; 0.03 to 0.10; or 0.05 to 0.10. Preferably, x may be 0.05 to 0.10.

The piezoelectric properties can vary depending on the composition ratio of PNN and PMN, which are relaxed ferroelectric materials. When x is in the above range, the composition of PNN and PMN compounds is optimally designed, so that the piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) are optimized, thereby achieving excellent piezoelectric properties.

According to one embodiment, the piezoelectric ceramic sintered body may have a Curie temperature of 250° C. to 300° C.

In general, when antimony is added to PZT in the form of PSN, a phenomenon of a decrease in the Curie temperature may occur. Accordingly, the thermal stability decreases, which makes it difficult to apply the piezoelectric vibrator which generates a lot of heat. Therefore, the Curie temperature may act as an important characteristic for use as a piezoelectric vibrator, and the piezoelectric ceramic sintered body according to the present invention can prevent a decrease in the Curie temperature due to the addition of antimony by adding antimony as a doping material to the PNN-PMN-PZT ceramic composition without replacing antimony with the ABO ₃ structure (Pb(Sb, Nb) _O 3 ).

The Curie temperature may preferably be 260° C. to 300° C., 260° C. to 290° C., or 270° C. to 290° C. When the Curie temperature is less than 250° C., the thermal stability may be poor and it may be difficult to apply it as a piezoelectric vibrator element.

In one embodiment, y may be from 0.05 to 0.10 and z may be from 0.50 to 0.52.

(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ + W wt% antimony (0.02≤y≤0.18, 0.50≤z≤0.55, 0.05<W<0.5), wherein y may be 0.02 to 0.15; 0.04 to 0.15; 0.04 to 0.12; 0.05 to 0.12; or 0.05 to 0.10. Preferably, y may be 0.05 to 0.10, and z may be 0.50 to 0.52.

The piezoelectric properties can vary depending on the composition ratio of PZN and PMN, which are relaxed ferroelectric materials, and the piezoelectric properties can vary due to phase transition depending on the Zr/Ti ratio of PZT. When y and z are within the above ranges, the degradation of properties caused by relaxed ferroelectric materials can be prevented, and the low phase transition can be compensated for, so that excellent temperature stability can be maintained even after long-term use. In addition, the piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) can be optimized, so that excellent piezoelectric properties can be achieved.

According to one embodiment, the piezoelectric ceramic sintered body may have a Curie temperature of 280° C. to 350° C.

In general, when antimony is added to PZT in the form of PSN, the Curie temperature decreases, which reduces thermal stability, making it difficult to apply to a piezoelectric vibrator that generates a lot of heat. The piezoelectric ceramic sintered body according to the present invention prevents a decrease in the Curie temperature due to the addition of antimony by adding antimony as a doping material to a PZN-PMN-PZT ceramic composition without replacing antimony with the ABO ₃ structure (Pb(Sb, Nb)O ₃ ).

Since a piezoelectric vibrator generates a lot of heat in the element itself while vibrating, if the Curie temperature, i.e. the phase transition temperature, is exceeded, the piezoelectricity is lost and the element itself may not operate. Therefore, the higher the Curie temperature, the higher the thermal stability, so that the element can operate as a piezoelectric vibrator without losing its characteristics. The PZN (Tc~140℃) has a higher phase transition temperature than PNN (Tc~120℃), so it can form a high Curie temperature in the above range, and it can be utilized in various piezoelectric application elements by compensating for the somewhat low Curie temperature for application as an element, and long-term reliability and lifespan can be improved.

The Curie temperature may preferably be 280° C. to 340° C., 300° C. to 340° C., or 300° C. to 320° C. When the Curie temperature is within the above range, it exhibits excellent thermal stability and can be applied as a piezoelectric vibrator element under optimal conditions.

The piezoelectric ceramic sintered body according to the present invention can exhibit piezoelectric properties such as a high Curie temperature that can be utilized as a piezoelectric vibrator as well as low heat dissipation during high-power operation due to a high piezoelectric coefficient (d ₃₃ ) and mechanical quality factor (Q _m ).

A method for manufacturing a piezoelectric ceramic sintered body according to the present invention comprises the steps of: adding a first raw material powder containing PbO, ZrO ₂ , TiO ₂ , NiO, Nb ₂ O ₅ and MnO ₂ or a second raw material powder containing PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ and MnO ₂ to a solvent so as to have a composition formula of the following chemical formula 1 or the following chemical formula 2, and preparing a mixture by a wet mixing method; drying the mixture and then calcining it to form a first powder; adding antimony to the first powder and then drying it after wet mixing to form a second powder; and forming and sintering the second powder to form a piezoelectric body;

[Chemical Formula 1]

(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ (hereinafter referred to as "PNN-PMN-PZT") (0.01≤x≤0.13)

[Chemical formula 2]

(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ (hereinafter referred to as “PZN-PMN-PZT”) (0.02≤y≤0.18, 0.50≤z≤0.55).

The method for manufacturing a piezoelectric ceramic sintered body according to the present invention can prevent a deterioration in the properties of the material by first synthesizing a PNN-PMN-PZT composition or a PZN-PMN-PZT composition and then adding antimony as a doping material.

The step of preparing the mixture may be to manufacture a PNN-PMN-PZT mixture using raw material powders including PbO, ZrO ₂ , TiO ₂ , NiO, Nb ₂ O ₅ and MnO ₂ so as to have the composition formula of the chemical formula 1. Specifically, the PNN-PMN-PZT mixture may be manufactured by including 0.1 to 1 mol (mol) of ZrO ₂ , 0.1 to 1 mol (mol) of TiO ₂ , 0.1 to 0.5 mol (mol) of NiO, 0.5 to 1.5 mol (mol) of Nb ₂ O _{5 ,} and 0.1 to 0.5 mol (mol) of MnO ₂ with respect to 1 mol (mol) of PbO. When the raw material powders are mixed in an amount outside the above range, a compound other than the PNN-PMN-PZT compound can be manufactured, and by optimally designing the composition of the PNN-PMN-PZT compound by controlling the mole fraction of the raw material powders as described above, it is possible to have piezoelectric properties such as a high piezoelectric coefficient (d ₃₃ ) and mechanical quality factor (Q _m ).

The above x may be 0.01 to 0.13; 0.01 to 0.12; 0.03 to 0.12; 0.03 to 0.10; or 0.05 to 0.10.

The step of preparing the mixture may be to manufacture a PZN-PMN-PZT mixture using raw material powders including PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ and MnO ₂ so as to have the composition formula of the chemical formula 2. Specifically, the PZN-PMN-PZT mixture may be manufactured by including 0.1 to 1 mol (mol) of ZrO ₂ , 0.1 to 1 mol (mol) of TiO ₂ , 0.1 to 0.5 mol (mol) of ZnO , 0.5 to 1.5 mol (mol) of Nb ₂ O _{5 ,} and 0.1 to 0.5 mol (mol) of MnO ₂ with respect to 1 mol (mol) of PbO. When the raw material powders are mixed in an amount outside the above range, a compound other than the PZN-PMN-PZT compound can be manufactured, and by optimally designing the composition of the PZN-PMN-PZT compound by controlling the mole fraction of the raw material powders as described above, it is possible to have piezoelectric properties such as a high piezoelectric coefficient (d ₃₃ ) and mechanical quality factor (Q _m ).

The above y may be 0.02 to 0.18; 0.02 to 0.15; 0.04 to 0.15; 0.04 to 0.12; 0.05 to 0.12; or 0.05 to 0.10; and the above z may be 0.50 to 0.55 or 0.50 to 0.52.

According to one embodiment, the step of preparing the mixture may be wet mixing the first raw material powder or the second raw material powder with at least one solvent selected from the group consisting of methanol, ethanol, isopropanol, and distilled water for 10 to 40 hours.

The present invention utilizes a general solid-state reaction method. The solid-state reaction method causes a reaction of powders at high temperature to obtain piezoelectric ceramic powder of a desired composition, and wet mixing is performed in a wet manner in a ball mill process performed to mix powders.

Specifically, the first raw material powder or the second raw material powder is mixed and placed in a jar, and wet-mixed with zirconia balls and a solvent for 10 to 40 hours. The preferable purity of the raw material powders may be 98% or higher. The solvent may be at least one selected from the group consisting of methanol, ethanol, isopropanol, and distilled water, but is not particularly limited as long as wet-mixing with the raw material powder is possible.

In one embodiment, the calcination may be performed at a temperature of 800° C. to 900° C.

The step of forming the first powder may be to prepare a PNN-PMN-PZT or PZN-PMN-PZT composition by calcining the dry mixture.

According to one embodiment, the calcination may be performed at a temperature range of 800° C. to 900° C. for 2 to 6 hours as a step for synthesizing the mixed powder. If the temperature and time ranges are exceeded, the crystallization of the piezoelectric material may not be appropriate, and the piezoelectric properties such as density, piezoelectric coefficient, and mechanical quality factor may deteriorate.

According to one embodiment, the antimony may include at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).

The step of forming the second powder is a step of adding antimony to the first powder, wet mixing, and then drying to form the second powder.

Preferably, the antimony may be antimony trioxide (Sb ₂ O ₃ ). Accordingly, the piezoelectric ceramic sintered body manufactured by the method for manufacturing the piezoelectric ceramic sintered body of the present invention is preferably (0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ + W wt% Sb ₂ O ₃ (0.01≤x≤0.13, 0.05<W<0.5) or (0.20y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1z Ti _z )O ₃ + W wt% Sb ₂ O ₃ (0.02≤y≤0.18, It can have a composition formula of 0.50≤z≤0.55, 0.05<W<0.5).

The antimony may be added in the range of 0.05 wt% to 0.5 wt% of the piezoelectric ceramic sintered body. Preferably, it may be 0.05 wt% to 0.4 wt%, 0.1 wt% to 0.4 wt%, or 0.1 wt% to 0.3 wt% of the piezoelectric ceramic sintered body. When the content of antimony is less than 0.05 wt%, the effect of improving the mechanical quality coefficient of the piezoelectric ceramic sintered body may not be exhibited, and when it exceeds 0.5 wt%, more defects such as oxygen vacancies may be generated inside the piezoelectric ceramic sintered body, which may affect a decrease in density and cause a problem of deterioration of the piezoelectric properties of the material.

In one embodiment, the sintering may be performed at a temperature of 900° C. to 1100° C. for 1 hour to 5 hours.

The step of forming the above piezoelectric body is a step of forming the second powder by pressing it into a desired shape and then sintering it to form the piezoelectric body.

The above molding may be performed by adding 5 to 20 wt% of polyvinyl alcohol (PVA) as a binder and applying pressure to form the mold. After the molding, the process of removing the binder at a temperature range of 400° C. to 600° C. for 30 minutes to 2 hours may be further included.

The above sintering may be performed at a temperature of 900° C. to 1050° C.; 950° C. to 1050° C.; or 950° C. to 1000° C.; for 1 hour to 4 hours; 2 hours to 4 hours; or 2 hours to 3 hours. Preferably, the sintering may be performed at a temperature of 950° C. to 1000° C. for 2 hours to 3 hours. When the sintering temperature is less than 900° C., crystallization of the piezoelectric material may not occur, and when it exceeds 1100° C., a change in the composition may occur due to volatilization of Pb, which may cause a problem of deterioration in the properties of the piezoelectric material.

The piezoelectric ceramic sintered body according to the present invention can exhibit an excellent mechanical quality factor by adding antimony, and does not exhibit a decrease in the Curie temperature due to the substitution of antimony, so that it is possible to implement a piezoelectric vibrator element having a high piezoelectric coefficient, electromechanical coupling coefficient, mechanical quality factor, and Curie temperature without deterioration of piezoelectric properties.

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

However, the following examples are only intended to illustrate the present invention, and the content of the present invention is not limited to the following examples.

Example

Manufacturing of piezoelectric ceramic sintered bodies

As starting materials, high purity powders of PbO, ZrO ₂ , TiO ₂ , NiO, Nb ₂ O ₅ , ZnO and MnO ₂ with a purity of 98% or higher from Kojundo Chemical Laboratory were used. The basic compositions were weighed according to various composition ratios, such as (0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ (PNN-PMN-PZT, x = 0.01-0.13) or (0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ (PZN-PMN-PZT, y = 0.02-0.18, z = 0.50-0.54). To uniformly disperse the powder, the raw material powder and zirconia balls were mixed together in an ethanol solution for 24 hours, and then dried at a temperature of 120°C for more than 4 hours. The mixed powder was synthesized by calcining at 850°C for 4 hours. The doping material, antimony trioxide ( _Sb2O3 ) _, was mixed with the manufactured powder by varying it from 0.1 wt% to 0.7 wt% for 24 hours. An appropriate amount of 10 wt% polyvinyl alcohol (PVA) aqueous solution as a binder was added to the raw material powder, and a pressure of about 10 MPa was applied to mold it into a disk shape with a diameter of 20 mm. A hydraulic pressure of 130 MPa was applied so that the molded ceramic had a denser structure, and sintering was performed at 1000°C for 2 hours.

FIG. 1 is a graph showing the results of measuring electrical characteristics of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the PMN content manufactured according to an embodiment of the present invention.

Referring to Fig. 1 (a), it can be confirmed that the piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) differ depending on the composition ratio of PNN-PMN-PZT according to the PMN content. The piezoelectric coefficient (d ₃₃ ) and electromechanical coupling coefficient (k _p ) were maximum at the composition where x = 0.04, and it could be confirmed that they decreased in proportion to the particle size as the PMN content increased above that content. On the other hand, the mechanical quality factor (Q _m ) may increase as the PMN content increases, as the particle size decreases and internal stress improves, making domain movement difficult. Therefore, when considering both particle size and electrical properties while forming a stable perovskite phase without secondary phase formation, the optimal composition ratio of 0.08Pb(Ni _1/3 Nb _2/3 )O ₃ -0.07Pb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃ was confirmed.

Referring to Fig. 1 (b), it can be confirmed that the piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) differ depending on the composition ratio of PZN-PMN-PZT according to the PMN content. It was confirmed that the piezoelectric coefficient (d ₃₃ ) and electromechanical coupling coefficient (k _p ) decreased as the PMN content increased. On the other hand, it was confirmed that the mechanical quality factor increased to a maximum at y = 0.06 and decreased thereafter. This may be the result of a rapid decrease in density. Therefore, when considering both particle size and electrical properties while forming a stable perovskite phase without secondary phase formation, the optimal composition ratio of 0.14Pb(Zn _1/3 Nb _2/3 )O ₃ -0.06Pb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃ was confirmed.

FIG. 2 is a graph showing the results of XRD analysis of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.

Referring to FIG. 2, it was confirmed that the pressure-sensitive ceramic sintered body manufactured according to the present invention formed a stable perovskite phase without the generation of a secondary phase. In particular, when antimony trioxide (Sb ₂ O ₃ ), which is a doping material, was added, it was confirmed that the Sb ³⁺ ion had a similar ionic radius and occupied a B-site with a high valence, thereby stabilizing the isotropic rhombohedral phase.

FIG. 3 is a SEM image of a PNN-PMN-PZT sintered body according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.

Referring to Fig. 3, as the doping content of antimony trioxide (Sb ₂ O ₃ ) increased, the average grain size decreased from 2.43 ㎛ to 1.17 ㎛. It is believed that the phase transition to a rhombohedral phase due to the increase in doping content affected the decrease in particle size.

FIG. 4 is a graph showing the density measurement results of PNN-PMN-PZT sintered bodies according to the antimony trioxide (Sb ₂ O ₃ ) doping content manufactured according to an embodiment of the present invention.

Referring to Fig. 4, when the doping content of antimony trioxide (Sb ₂ O ₃ ) was 0.1 wt% to 0.3 wt%, an excellent value of relative density of about 98% was shown. It is judged that the density value decreased as the particle size decreased as the doping amount of antimony trioxide (Sb ₂ O ₃ ) increased.

FIG. 5 is a graph showing the results of measuring electrical characteristics of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies according to the doping content of antimony trioxide (Sb ₂ O ₃ ) manufactured according to an embodiment of the present invention.

Referring to Fig. 5 (a), when the doping content of antimony trioxide (Sb ₂ O ₃ ) was 0.3 wt%, the piezoelectric coefficient (d ₃₃ ), electromechanical coupling coefficient (k _p ), and mechanical quality factor (Q _m ) showed the best values of 372 pC/N, 0.54, and 1151, respectively. It is considered that this is because the 4-component basic composition in which relaxor-type ferroelectric materials such as PNN and PMN are substituted for the PZT system, and antimony trioxide (Sb ₂ O ₃ ), which can generate oxygen vacancies inside the crystal and improve the mechanical quality factor value, has excellent piezoelectric properties due to the doping effect.

Referring to Fig. 5 (b), it was confirmed that the piezoelectric constant (d ₃₃ ) and the electromechanical coupling factor (k _p ) decreased as the antimony trioxide (Sb ₂ O ₃ ) content increased, while the mechanical quality factor (Q _m ) increased. The mechanical quality factor (Q _m ) showed the best value of 1237 when the doping content of antimony trioxide was 0.1 wt%, and the piezoelectric constant (d ₃₃ ) and the electromechanical coupling factor (k _p ) also showed good values of 338 pC/N and 0.56.

_FIG . 6 is a graph showing the results of measuring dielectric properties according to temperature changes at 1 kHz of (a) PNN-PMN-PZT sintered bodies and (b) PZN-PMN-PZT sintered bodies with different antimony trioxide (Sb ₂ O 3 ) doping contents manufactured according to an embodiment of the present invention.

Referring to (a) of Fig. 6, when the antimony trioxide (Sb ₂ O ₃ ) doping content was 0.1 wt% to 0.3 wt%, the Curie temperature did not decrease compared to the case where antimony trioxide was not added, and referring to (b) of Fig. 6, when the antimony trioxide (Sb ₂ O ₃ ) doping content was 0.1 wt%, the Curie temperature did not decrease compared to the case where antimony trioxide was not added.

The above results show that when antimony trioxide (Sb ₂ O ₃ ) is substituted for the PZT system with a complex perovskite compound such as Pb(B'B”)O ₃ , the substituted metal ions first react to form a secondary phase such as a pyrochlore phase, which leads to a deterioration of the piezoelectric properties of the material. Therefore, it is judged that the development of a material without deterioration of properties is possible by adding it as a doping material to a composition synthesized with the PNN-PMN-PZT system or the PZN-PMN-PZT system. In addition, it is judged that when the doping material antimony trioxide (Sb ₂ O ₃ ) is 0.5 wt% or more, more defects such as oxygen vacancies are created inside the sintered body, which deteriorates the piezoelectric properties of the material and also lowers the temperature stability.

FIG. 7 is a graph showing (a) the electrical property measurement results and (b) the dielectric property measurement results of a PZN-PMN-PZT sintered body according to the Ti content manufactured according to an embodiment of the present invention.

Referring to Fig. 7 (a), when the Zr/Ti ratio was 49/51, the piezoelectric coefficient and mechanical quality factor showed maximum values of 361 pC/N and 1234, respectively, due to an increase in the poling efficiency.

Referring to Fig. 7 (b), since the Curie temperature of PbTiO ₃ (Tc~490 ℃) is generally higher than that of PbZrO ₃ (Tc~230 ℃), the Curie temperature was confirmed to be higher in the case of a composition ratio of 49/51 with a higher Ti content than when the contents of Zr and Ti are the same. However, the Curie temperature decreased after a composition ratio of 48/51, which showed the same trend as the piezoelectric coefficient (d ₃₃ ). Therefore, by optimally changing the Zr/Ti ratio in the optimized 0.14PZN-0.06PMN-0.80Pb(Zr _1-z Ti _z )O ₃ composition with added antimony, it is possible to develop a piezoelectric ceramic sintered body exhibiting a high Curie temperature without the problem of deterioration of the piezoelectric coefficient (d ₃₃ ) and mechanical quality factor (Q _m ).

Through this, the piezoelectric ceramic sintered body according to the present invention can develop a PZT-based piezoelectric ceramic composition including antimony, thereby producing a piezoelectric material for a piezoelectric vibrator having superior piezoelectric characteristic values compared to existing commercialized materials without adding expensive rare elements.

Although the embodiments have been described above, those skilled in the art will appreciate that various technical modifications and variations can be applied based on the above. For example, appropriate results can be achieved even if the described techniques are performed in a different order than the described method, and/or components of the described system, structure, device, circuit, etc. are combined or combined in a different form than the described method, or are replaced or substituted by other components or equivalents.

Therefore, other implementations, other embodiments, and equivalents to the claims are also included in the scope of the claims described below.

Claims (14)

A PNN-PMN-PZT ceramic composition of the following chemical formula 1 or a PZN-PMN-PZT ceramic composition of the following chemical formula 2; and
Antimony added to it;
Including
Piezoelectric ceramic sintered body:
[Chemical Formula 1]
(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃
(0.01≤x≤0.13)
[Chemical formula 2]
(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃
(0.02≤y≤0.18, 0.50≤z≤0.55).
In the first paragraph,
The above antimony comprises at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).
Piezoelectric ceramic sintered body.
In the first paragraph,
The above antimony is 0.05 wt% to 0.5 wt% of the piezoelectric ceramic sintered body.
Piezoelectric ceramic sintered body.
In the first paragraph,
Add more hardener;
The above hardener comprises at least one selected from the group consisting of iron oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and cobalt oxide (Co ₂ O ₃ ).
Piezoelectric ceramic sintered body.
In the first paragraph,
The above piezoelectric ceramic sintered body has a piezoelectric coefficient of 300 pC/N to 500 pC/N and a mechanical quality coefficient of 1000 to 1500.
Piezoelectric ceramic sintered body.
In the first paragraph,
wherein the above x is between 0.05 and 0.10,
Piezoelectric ceramic sintered body.
In the first paragraph,
The above piezoelectric ceramic sintered body has a Curie temperature of 250°C to 300°C.
Piezoelectric ceramic sintered body.
In the first paragraph,
The above y is 0.05 to 0.10,
The above z is 0.50 to 0.52,
Piezoelectric ceramic sintered body.
In the first paragraph,
The above piezoelectric ceramic sintered body has a Curie temperature of 280°C to 350°C.
Piezoelectric ceramic sintered body.
A step of preparing a mixture by a wet mixing method by adding a first raw material powder including PbO, ZrO ₂ , TiO ₂ , NiO, Nb ₂ O ₅ and MnO ₂ or a second raw material powder including PbO, ZrO ₂ , TiO ₂ , ZnO, Nb ₂ O ₅ and MnO ₂ to a solvent so as to have a composition formula of the following chemical formula 1 or the following chemical formula 2;
A step of forming a first powder by drying and then calcining the above mixture;
A step of adding antimony to the first powder, wet mixing, and drying to form a second powder; and
A step of forming a piezoelectric body by molding and sintering the second powder;
Including,
Method for manufacturing piezoelectric ceramic sintered body:
[Chemical Formula 1]
(0.15-x)Pb(Ni _1/3 Nb _2/3 )O ₃ -xPb(Mn _1/3 Nb _2/3 )O ₃ -0.85Pb(Zr _0.5 Ti _0.5 )O ₃
(0.01≤x≤0.13)
[Chemical formula 2]
(0.20-y)Pb(Zn _1/3 Nb _2/3 )O ₃ -yPb(Mn _1/3 Nb _2/3 )O ₃ -0.80Pb(Zr _1-z Ti _z )O ₃
(0.02≤y≤0.18, 0.50≤z≤0.55).
In Article 10,
The step of preparing the mixture is wet mixing the first raw material powder or the second raw material powder with at least one solvent selected from the group consisting of methanol, ethanol, isopropanol, and distilled water for 10 to 40 hours.
Method for manufacturing piezoelectric ceramic sintered body.
In Article 10,
The above calcination is performed at a temperature of 800 ℃ to 900 ℃.
Method for manufacturing piezoelectric ceramic sintered body.
In Article 10,
The above antimony comprises at least one selected from the group consisting of antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), antimony trichloride (SbCl ₃ ), and antimony trisulfide (Sb ₂ S ₃ ).
A method for manufacturing a sintered ceramic body.
In Article 10,
The above sintering is performed at a temperature of 900°C to 1100°C for 1 to 5 hours.
Method for manufacturing piezoelectric ceramic sintered body.

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