KR100403302B1 - A method for preparing Pb-based peizoelectric ceramic powder containing the carbonate - Google Patents

Abstract

Provided is a method for preparing Pb-based piezoceramic powder including carbonate.

The present invention, after preparing a raw material powder consisting of PbO, TiO ₂ and carbonate, mixing and drying it; Firstly calcining the dried powder at a temperature of 600 to 700 ° C .; Second calcination of the first calcined powder at a temperature of 800 to 1200 ° C .; And pulverizing and drying the secondary calcined powder.

Preparing a raw material powder consisting of PbO, TiO ₂ , ZrO ₂ and carbonate, and then mixing and drying the powder; Primary calcination of the dried powder at a temperature of 750-850 ° C .; Secondly calcining the first calcined powder at a temperature of 850˜1200 ° C .; It relates to a PZT-based piezoceramic powder manufacturing method comprising a; and pulverizing and drying the secondary calcined powder.

Description

A method for preparing Pb-based peizoelectric ceramic powder containing the carbonate}

The present invention relates to a Pb-based piezoceramic powder manufacturing method comprising a carbonate, and more particularly, to a Pb-based piezoceramic powder manufacturing method that can maximize the compatibility while minimizing the volatilization of PbO through a two-stage calcination process. will be.

In general, ceramics have their properties determined by thermodynamic and kinetic variables, which determine the quality limits of the product.

Ceramic powder is usually manufactured through a weighing, mixing, drying, and calcination process, wherein the calcination process is an important process that determines the compatibility and properties of the powder. Particularly, in the case of piezoelectric ceramics containing Pb, volatilization of PbO simultaneously occurs with morphology at the time of calcination. The characteristics will also vary. In other words, the technique of controlling the volatilization and compatibility of PbO by the calcination process is the technical basis for producing piezoelectric ceramics of desired physical properties.

Pb-based piezoceramic is composed of PbTiO ₃ and PbZrO ₃ as a basic composition, and controls the characteristics in the manufacturing process, and other elements are substituted for B-site and A-site. That is, in the case of A-site, elements such as La, Sm, Nd, Ba, Sr, and Ca are substituted for Pb, and Ba, Sr, and Ca are carbonate forms such as BaCO ₃ , SrCO ₃ , and CaCO ₃ . Is added. To be added in the form of carbonate, not in the form of BaO, CaO, SrO or before adding carbonate, it must be decomposed first, but these elements are unstable and difficult to handle quantitatively in the air. There are drawbacks to the complexity and complexity of the process.

When added in the form of carbonate, quantitative control becomes easier in the process, but the calcination temperature is determined by the temperature at which the carbonate is decomposed. In general, the temperature at which the carbonate is decomposed is higher than that of the Pb-based piezoceramic, and the volatilization of PbO increases at the same time as the calcination. Increasing volatilization of PbO deviates the stoichiometry of the composition and adversely affects the piezoelectric properties. Therefore, setting of calcination conditions is very important in the production of Pb-based piezoelectric ceramics containing carbonates.

A conventional process for producing Pb-based piezoelectric ceramics is shown in FIG. That is, as shown in Figure 1, after weighing the raw material powder, such as PbO, TiO ₂ , ZrO ₂ to the molar ratio and mix it. Then, the mixed raw material powder is dried again, and subsequently, calcination is performed at a temperature rising rate of 1 to 5 ° C./min at a temperature of 850 to 1200 ° C. to prepare Pb-based piezoceramic powder based on PbTiO ₃ and PbZrO ₃ . It was.

In the above conventional process, when carbonate is included in the raw material, decomposition of CO ₂ should be considered simultaneously with the compatibility.

Because calcination of raw powder containing carbonate at the same calcination temperature without carbonate does not completely decompose CO ₂ , so it is difficult to synthesize perovskite phase and decrease density and electrical characteristics during sintering. This is because there is a problem of deterioration.

In view of the above, when carbonate is included in the raw material, the calcination temperature can be increased to achieve complete decomposition of the CO ₂ gas in the carbonate, but the calcination temperature is too high. There is a problem that it may intensify and result in stoichiometric non-uniformity of the composition, leading to deterioration of properties.

Accordingly, the present invention is to solve the problems of the prior art, unlike the one-stage calcination step of reacting by maintaining a constant time by raising the temperature to the previous final calcination temperature, two stages in consideration of decomposition of carbonate and minimizing PbO volatile content It is an object of the present invention to provide a Pb-based piezoceramic powder manufacturing method excellent in dielectric properties and piezoelectric properties to be calcined.

1 is a manufacturing process diagram of a conventional Pb-based piezoceramic

2 is a manufacturing process diagram of the Pb-based piezoceramic of the present invention

The present invention for achieving the above object,

Preparing a raw material powder consisting of PbO, TiO ₂ and carbonate, and then mixing and drying the powder; Firstly calcining the dried powder at a temperature of 600 to 700 ° C .; Second calcination of the first calcined powder at a temperature of 800 to 1200 ° C .; And pulverizing and drying the second calcined powder.

In addition, the present invention, after preparing a raw material powder consisting of PbO, TiO ₂ , ZrO ₂ and carbonate, mixing and drying them; Primary calcination of the dried powder at a temperature of 750-850 ° C .; Secondly calcining the first calcined powder at a temperature of 850˜1200 ° C .; It relates to a PZT-based piezoceramic powder manufacturing method comprising a; and pulverizing and drying the secondary calcined powder.

As described above, in order to manufacture Pb-based piezoelectric ceramic powders having excellent dielectric and piezoelectric properties, calcination conditions that can exhibit optimum physical properties in consideration of decomposition of carbonate, synthesis of perovskite phase, and volatilization of PbO are set. This is very important. However, conventionally, as soon as the temperature is immediately raised to the final calcination temperature and maintained for a certain time, the synthesis results, and the volatilization of PbO is intensified, resulting in stoichiometric nonuniformity of the composition, leading to deterioration of characteristics.

Therefore, in the present invention, the raw material powder is first calcined in a temperature range capable of minimizing PbO volatilization before reaching the final calcining temperature, and then the perovskite phase is first synthesized, and then maintained at the final calcining temperature to thereby carry out two-stage calcining treatment. It is characterized by adopting a two-stage calcination process that can effectively synthesize the residual material is not completed decomposition and synthesis of carbonate.

Hereinafter, the present invention will be described.

2 is a manufacturing process diagram of the Pb-based piezoelectric ceramic powder according to the present invention.

As shown in FIG. 2, in the present invention, the raw materials are first weighed and mixed according to their molar ratios to prepare raw material powders, and then uniformly mixed in a ball mill for 24 hours, and then subjected to normal conditions of about 120 ° C. FIG. Dry.

In general, Pb-based piezoceramics are largely divided into PZT [Pb (Zr _1-x Ti _x ) O ₃ ] and PT [PbTiO ₃ ] based, and thus, the starting materials are different. That is, in the PT composite perovskite piezoceramic, PbO, TiO ₂ and carbonate are the basic starting materials, and in the case of PZT, PbO, TiO ₂ , ZrO ₂ and carbonate are the basic starting materials.

Carbonate in the above-described raw materials is added to improve piezoelectric properties and has an element for substituting A-site, that is, Pb, in a piezoelectric ceramic having a Pb-based composite perovskite structure. Preferably, the carbonate includes one or two or more of LaCO ₃ , SmCO ₃ , NdCO ₃ , BaCO ₃ , SrCO ₃ and CaCO ₃ .

In addition, in the present invention, in order to produce a piezoelectric ceramic having excellent mechanical quality coefficients, Mg, Nb, Ni, Zn, W, Ta, Co, Fe, Sb, Sn, Cr, Su, In, Yb, Sc It is preferable to add one or two or more of Cd and Lu in the form of an oxide.

The raw material powder dried as described above is calcined in two stages as described above. In detail, in the present invention, the raw material powder dried first is heated to 1 to 5 ° C./min and subjected to first calcination to produce a perovskite phase such as PbTiO ₃ , PbZrO ₃ and Pb (Zr, Ti) O ₃ . Form.

At this time, the primary calcination temperature varies depending on the type of Pb-based piezoceramic.For PT [PbTiO ₃ ] system, 600 ~ 700 ℃, and PZT [Pb (Zr _1-x Ti _x ) O ₃ ] system, 750 ~ 850 Preferably limited to ° C. This is because the synthesis of perovskite phase can be maximized while PbO volatilization is suppressed in this temperature range. More preferably, the PT [PbTiO ₃ ] system is limited to 600 to 650 ° C and the PZT [Pb (Zr _1-x Ti _x ) O ₃ ] system to 800 to 850 ° C.

In addition, it is preferable to calcination for 1 to 3 hours at the temperature.

Next, after the first calcination treatment, the temperature is increased again to perform the second calcination treatment, thereby completing the decomposition of the carbonate and the compatibility of the incomplete residual material. At this time, the secondary calcination temperature also varies depending on the type of Pb-based piezoceramic. For PT [PbTiO ₃ ] system, 800 ~ 1200 ℃, and PZT [Pb (Zr _1-x Ti _x ) O ₃ ] system, 850 ~ 1200 It is preferable to limit to ℃

Preferably, it is calcined for 1 to 3 hours at the temperature.

In the present invention, Pb-based piezoceramic powder having excellent piezoelectric properties can be manufactured by pulverizing the ceramic powder having a homogeneity completed by the calcination process to the same particle size and then drying it under normal conditions (about 120 ° C.). The ceramic powder is preferably pulverized by the wet method.

In the present invention, the ceramic powder prepared as described above is molded into an appropriate size and shape, and then sintered at a normal temperature of 1000 to 1300 ° C, followed by post-sintering processes such as polishing, electrode formation, and polarization treatment. Through the process, Pb-based piezoceramic excellent in dielectric and piezoelectric properties can be produced.

Hereinafter, the present invention will be described in detail through examples.

(Example 1)

Pb _0.90 Ba _0.10 (Mn _1/3 Nb _2/3 ) _0.06 (Sn _1/3 Nb _2/3 ) _0.09 Ti _0.436 Zr _0.414 O ₃ System and Pb _0.90 Sr _0.10 (Mn _1/3 Nb _2/3 ) _0.06 ( _{Sn 1/3 Nb 2/3) 0.09 Ti 0.436} Zr 0.414 O to a compound perop Sky-like composite having a composition of ₃ family, was prepared from a raw material consisting of PbO, TiO _2, ZrO _2, carbonates and oxides, respectively. Then, these were weighed to a molar ratio, and then mixed by ball milling for 24 hours, and dried at 120 ° C., respectively.

First, each dried powder was heated up at a rate of temperature increase rate of 1 to 5 ° C./min as in the conventional method and immediately maintained at 1000 ° C., which is the final calcination temperature, to synthesize composite perovskite phases, respectively.

Next, after heating each dried powder as described in the present invention, the first calcination at 850 ℃ for 2 hours, and then again heated to secondary calcination at 1000 ℃ to synthesize a PZT-based composite perovskite phase.

On the other hand, as a result of measuring the volatilization amount of PbO in the second step after the synthesis, it can be seen that the conventional method is 0.6wt%, while the volatilization amount is 0.25wt%.

The powder synthesized by the two methods was pulverized to the same particle size and then molded into a diameter of 20 mm and a thickness of 1 mm, and the molded specimen was heated at a rate of 1 to 20 ° C./min and sintered at 1050 ° C. The sintered specimens were polished to a thickness of 0.5mm and then heat-treated with Ag electrodes.

The electrode treatment was completed in the polarization treatment according to the conditions of 25 ~ 200 ℃, 2 ~ 10kV / mm, 5 ~ 40 minutes, and the dielectric loss, dielectric constant, area vibration mode after heat treatment of the polarized specimens at 180 ℃ 1 hour The electromechanical coefficient (kp) and the mechanical quality factor (Qm) of were measured. Table 1 shows the measurement results of Pb _0.90 Ba _0.10 (Mn _1/3 Nb _2/3 ) _0.06 (Sn _1/3 Nb _2/3 ) _0.09 Ti _0.436 Zr _0.414 O ₃ -based specimens, and Table 2 shows Pb _0.90 Sr _0.10 (Mn _1/3 Nb _2/3 ) _0.06 (Sn _1/3 Nb _2/3 ) _0.09 Ti _0.436 Zr _0.414 O _{3 Based} on test results.

Permittivity (ε) Dielectric loss (tan δ:%) kp Qm Invention method (two steps calcining) 1712 0.48 0.53 1681 Conventional method (stage 1) 1630 0.52 0.5 1600

Permittivity (ε) Dielectric loss (tan δ:%) kp Qm Invention method (two steps calcining) 1760 0.52 0.50 1633 Conventional method (stage 1) 1675 0.6 0.47 1521

As shown in Table 1 and Table 2, when comparing the dielectric properties and piezoelectric properties of the present invention method adopting the conventional method and the two-stage calcination process, the dielectric method of the present invention increases but the dielectric loss decreases, and the area vibration Both the modulus and mechanical quality coefficients of the modes were also increased. This is because, as described above, the volatilization amount of PbO can be reduced in the present invention adopting the two-stage calcination method, and the stoichiometric nonuniformity of the composition due to the volatilization is prevented to prevent the characteristic from being lowered.

(Example 2)

Composite Perovskite Phase with Pb _0.80 Ca _0.20 (Co _1/2 , W _1/2 ) _0.04 Ti _0.96 O ₃ System and Pb _0.80 Sr _0.20 (Co _1/2 , W _1/2 ) _0.04 Ti _0.96 O ₃ System For synthesis, starting materials consisting of PbO, TiO ₂ carbonate and oxide were prepared, respectively. And these were weighed according to the molar ratio and then mixed by ball milling for 24 hours, and dried at 120 ° C., respectively.

First, each dried powder was heated up at a rate of temperature increase rate of 1 to 5 ° C./min as in the conventional method and immediately maintained at 1000 ° C., which is the final calcination temperature, to synthesize composite perovskite phases, respectively.

Next, after heating each dried powder as described in the present invention, the first calcined at 700 ℃ for 2 hours, and then heated again to the second calcined at 1000 ℃ to synthesize a PT composite perovskite phase.

On the other hand, as a result of measuring the volatilization amount of PbO in the two methods after this synthesis, it can be seen that the conventional method is 0.7wt%, while the volatilization amount is reduced to 0.3wt%.

The powder synthesized by the two methods was pulverized to the same particle size and then molded into a diameter of 20 mm and a thickness of 1 mm, and the molded specimen was heated at a rate of 1 to 20 ° C./min and sintered at 1050 ° C. The sintered specimens were polished to a thickness of 0.5mm and then heat-treated with Ag electrodes.

The electrode treatment was completed in the polarization treatment according to the conditions of 25 ~ 200 ℃, 2 ~ 10kV / mm, 5 ~ 40 minutes, and the dielectric loss, dielectric constant, thickness vibration mode after heat treatment of the polarized specimens at 180 ℃ 1 hour The electromechanical coefficient (kt) and mechanical quality factor (Qm) of were measured. Table 3 below shows Pb _0.80 Ca _0.20 (Co _1/2 , W _1/2 ) _0.04 Ti _0.96 O ₃ -based specimens, and Table 4 below shows Pb _0.80 Sr _0.20 (Co _1/2 , W _{1 / 2} ) _Show measured value of _0.04 Ti _0.96 O _{3 type} specimen.

Permittivity (ε) Dielectric loss (tan δ:%) kt Qm Invention method (two steps calcining) 200 0.43 0.52 500 Conventional method (stage 1) 188 0.52 0.49 400

Permittivity (ε) Dielectric loss (tan δ:%) kt Qm Invention method (two steps calcining) 205 0.42 0.52 420 Conventional method (stage 1) 190 0.51 0.48 360

As shown in Table 3 and Table 4, when comparing the dielectric properties and piezoelectric properties of the present invention method adopting the conventional method and the two-stage calcination process, the present invention increased the dielectric constant, but the dielectric loss was reduced and area vibration Both the modulus and mechanical quality coefficients of the modes were also increased. This is because the volatilization amount of PbO is effectively reduced in the calcination process of the present invention employing the two-stage calcination method.

(Example 3)

Pb _0.60 Ba _0.25 (La _1/2 Nd _1/2 ) _0.10 TiO ₃ system, Pb _0.60 Sr _0.25 (La _1/2 Nd _1/2 ) _0.10 TiO ₃ system and Pb _0.60 Ca _0.25 (La _1/2 Nd _{1 / 2} ) For the synthesis of composite perovskite phase having _0.10 TiO ₃ -based component, starting materials consisting of PbO, TiO ₂ carbonate and oxide were prepared, respectively. And these were weighed according to the molar ratio and then mixed by ball milling for 24 hours, and dried at 120 ° C., respectively.

First, each dried powder was heated up at a rate of temperature increase rate of 1 to 5 ° C./min as in the conventional method and immediately maintained at 1000 ° C., which is the final calcination temperature, to synthesize composite perovskite phases, respectively.

Next, after heating each dried powder as described in the present invention, the first calcined at 700 ℃ for 2 hours, and then heated again to the second calcined at 1000 ℃ to synthesize a PT composite perovskite phase.

On the other hand, as a result of measuring the volatilization amount of PbO in the two methods after this synthesis, it can be seen that the conventional method is 0.7wt%, while the volatilization amount is reduced to 0.3wt%.

The powder synthesized by the two methods was pulverized to the same particle size and then molded into a diameter of 20 mm and a thickness of 1 mm, and the molded specimen was heated at a rate of 1 to 20 ° C./min and sintered at 1050 ° C. The sintered specimens were polished to a thickness of 0.5mm and then heat-treated with Ag electrodes.

The electrode treatment was completed in the polarization treatment according to the conditions of 25 ~ 200 ℃, 2 ~ 10kV / mm, 5 ~ 40 minutes, and the dielectric loss, dielectric constant, thickness vibration mode after heat treatment of the polarized specimens at 180 ℃ 1 hour The electromechanical coupling coefficient (kt), the electromechanical coupling coefficient (kp) of the area vibration mode, and the mechanical quality coefficient (Qm) were measured.

Tables 5 and 6 show the specimens of the Pb _0.60 Ba _0.25 (La _1/2 Nd _1/2 ) _0.10 TiO ₃ system and the Pb _0.60 Sr _0.25 (La _1/2 Nd _1/2 ) _0.10 TiO ₃ system, respectively. Table 7 shows the measurement results of Pb _0.60 Ca _0.25 (La _1/2 Nd _1/2 ) _0.10 TiO ₃ -based specimens.

Permittivity (ε) Dielectric loss (tan δ:%) kt kp Qm Invention method (two steps calcining) 390 0.47 0.55 10.5 1950 Conventional method (stage 1) 350 0.55 0.52 10.2 1853

Permittivity (ε) Dielectric loss (tan δ:%) kt kp Qm Invention method (two steps calcining) 690 2.00 0.55 15.0 680 Conventional method (stage 1) 650 2.37 0.52 14.3 380

Permittivity (ε) Dielectric loss (tan δ:%) kt kp Qm Invention method (two steps calcining) 490 0.52 0.55 12.7 2510 Conventional method (stage 1) 450 0.64 0.53 12.2 2341

As shown in Tables 5, 6 and 7, comparing the dielectric properties and piezoelectric properties of the present invention method employing the conventional method and the two-stage calcination process, the present invention increased the dielectric constant, but the dielectric loss decreased rather than the area Both the electromechanical coupling coefficient and the mechanical quality coefficient of the vibration mode and the thickness vibration mode were also increased.

As described above, the present invention adopts a two-stage calcination process, which is different from the past, so that it is possible to maximize the synthesis of perovskite phase while minimizing the volatilization of PbO. It works.

Claims (8)

Preparing a raw material powder consisting of PbO, TiO ₂ and carbonate, and then mixing and drying the powder; Firstly calcining the dried powder at a temperature of 600 to 700 ° C .; Second calcination of the first calcined powder at a temperature of 800 to 1200 ° C .; And PT-based piezoceramic powder manufacturing method comprising a; pulverizing and drying the secondary calcined powder. The method of claim 1, wherein the carbonate is one or two or more selected from LaCO ₃ , SmCO ₃ , NdCO ₃ , BaCO ₃ , SrCO ₃ and CaCO ₃ . According to claim 1, wherein the raw material is one or two selected from Mg, Nb, Ni, Zn, W, Ta, Co, Fe, Sb, Sn, Cr, Su, In, Yb, Sc, Cd and Lu The above method further comprises in the form of an oxide. The method of claim 1, wherein the dried powder is first calcined at 600 ~ 650 ℃. Preparing a raw material powder consisting of PbO, TiO ₂ , ZrO ₂ and carbonate, and then mixing and drying the powder; Primary calcination of the dried powder at a temperature of 750-850 ° C .; Secondly calcining the first calcined powder at a temperature of 850˜1200 ° C .; And PZT-based piezoceramic powder manufacturing method comprising the step of grinding and drying the secondary calcined powder. The method of claim 5, wherein the carbonate is one or two or more selected from LaCO ₃ , SmCO ₃ , NdCO ₃ , BaCO ₃ , SrCO ₃ and CaCO ₃ . The method of claim 5, wherein the raw material is one or two selected from Mg, Nb, Ni, Zn, W, Ta, Co, Fe, Sb, Sn, Cr, Su, In, Yb, Sc, Cd and Lu The above method further comprises in the form of an oxide. The method of claim 5, wherein the dried powder is first calcined at 800 ~ 850 ℃.