KR100426722B1 - Composition of piezoelectric ceramics and method for preparing same - Google Patents

Abstract

The present invention relates to a piezoelectric ceramic composition for a voltage type accelerometer and a method of manufacturing the same, which comprises reacting and calcining nickel oxide and niobium oxide in the presence of a solvent and a dispersant to produce nickel niobate and niobic acid prepared above in the presence of a solvent. It is a method of manufacturing a piezoelectric ceramic composition of the formula (1) comprising the step of adding and calcining lead oxide, titanium oxide, zirconium oxide and manganese dioxide to nickel. The piezoelectric ceramic composition of the present invention has a high piezoelectric voltage constant and a Curie temperature, and greatly improves the aging phenomenon, so that the piezoelectric ceramic composition can be used for a highly practical voltage type acceleration sensor.

[Formula 1]

aPb (Ni _1/3 Nb _2/3 ) O ₃ -bPbZrO ₃ -cPbTiO ₃ + xMnO ₂

Wherein a is 0.2 ≦ a ≦ 0.4 in molar ratio, b is 0.25 ≦ b ≦ 0.45 in molar ratio, c is 0.25 ≦ c ≦ 0.45 in molar ratio and x is 0.1 ≦ x ≦ 0.5 in weight percent of the total amount of the composition.

Description

Piezoelectric ceramic composition and method for preparing the same {Composition of piezoelectric ceramics and method for preparing same}

[Industrial use]

The present invention relates to a piezoelectric ceramic composition, and more particularly, to a piezoelectric ceramic composition for a voltage type acceleration sensor having a high piezoelectric voltage constant and a Curie temperature and greatly improving aging, and a method of manufacturing the same.

[Prior art]

The acceleration sensor is a sensor that can directly detect the dynamic vibration change (acceleration) of the object. The acceleration sensor using piezoelectric ceramics as a key element for signal detection generates an electrical signal that is proportional to the magnitude of the mechanical vibration signal applied to the piezoelectric body. It is a sensor to know the vibration state of

Such an acceleration sensor is classified into a voltage type and a charge type according to the type of the output signal. In the case of the voltage type, the electrical signal generated from the piezoelectric body is output as a voltage signal through an impedance converter.

In general, as a piezoelectric material for a voltage type acceleration sensor, the piezoelectric voltage constant (d ₃₃ ) is large, so the sensitivity to the vibration signal is large, and the Curie temperature (T _c ), which is a temperature at which the piezoelectric properties of the piezoelectric material disappears, is high, which greatly affects the use temperature change. The composition that does not receive is required.

Conventionally used voltage accelerometers include single crystal materials such as quartz and three-component systems based on PZT (Pb (Ti _x Zr _y ) O ₃ ). The single crystal materials such as quartz are reproducible. Although there is an advantage of obtaining this high data, there is a problem that the manufacturing cost increases and the sensitivity is significantly lowered because the piezoelectric voltage constant is low because it must be manufactured by a single crystal growth technique such as Czochralski method.

In addition, conventional three-component materials based on PZT are typical piezoelectric ceramics that have been commercialized and have high piezoelectric voltage constants, which have high sensitivity but relatively low Curie temperatures, which not only lower the stability of use and limit the use temperature of piezoelectric ceramics. There is a problem that the sensitivity is lowered over time because of the characteristic aging phenomenon.

The present invention is to solve the above problems, an object of the present invention is to provide a method for producing a piezoelectric ceramic composition suitable for a voltage type acceleration sensor, the piezoelectric voltage constant and curie temperature is high and the aging is remarkably improved.

In order to achieve the above object, the present invention

a) reacting and calcining nickel oxide and niobium oxide in the presence of a solvent and a dispersant to produce nickel niobate; And

b) adding and calcining lead oxide, titanium oxide, zirconium oxide and manganese dioxide to the nickel niobate prepared above in the presence of a solvent

Manganese dioxide (MnO ₂ ) in a method comprising a by the amount of 0.1 to 0.5% by weight based on the total amount of the piezoelectric ceramic composition

[Formula 1]

aPb (Ni _1/3 Nb _2/3 ) O ₃ -bPbZrO ₃ -cPbTiO ₃ + xMnO ₃

Wherein a is 0.2 ≦ a ≦ 0.4 in molar ratio, b is 0.25 ≦ b ≦ 0.45 in molar ratio, c is 0.25 ≦ c ≦ 0.45 in molar ratio and x is 0.1 ≦ x ≦ 0.5 in weight percent of the total amount of the composition )

A piezoelectric ceramic composition is provided.

Hereinafter, the present invention will be described in more detail.

In order to prepare the piezoelectric ceramic composition of the present invention, nickel niobate (NiNb ₂ O ₆ ) is prepared by reacting nickel oxide (NiO) and niobium oxide (Nb ₂ O ₅ ).

Nickel oxide and niobium oxide are quantitated 1: 1 in a molar ratio (nickel oxide: niobium oxide), placed in a ball mill, and then a solvent and a dispersant are added thereto, mixed uniformly and ground to prepare a reaction mixture.

The molar ratio of nickel oxide to niobium oxide for producing the nickel niobate is preferably maintained in the above ratio in order to compare the values for the physical properties.

As a solvent used to prepare the nickel niobate, ethanol, methanol, acetone, distilled water, and the like may be used, and a solvent to be used is selected in consideration of a combination with a dispersant used. It is preferable to use ethanol for dispersion. The amount of the solvent is preferably used in an amount suitable to maintain the viscosity required to achieve the mixing and grinding effect of nickel oxide and niobium oxide.

Various kinds of dispersants may be used depending on the solvent used, but it is preferable to use ammonia water (NH ₄ OH) because nickel oxide and niobium oxide can be efficiently dispersed together with ethanol as the solvent.

The mixing and grinding time of the mixture is sufficient to obtain a uniform fine mixture, preferably 15 to 40 hours.

The homogeneously mixed mixture was dried and transferred to an alumina crucible having a temperature of 800 to 1500 ° C. and calcined for about 1 to 5 hours to prepare nickel niobate.

Next, lead oxide (PbO), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and manganese dioxide (MnO ₂ ) are added to the nickel niobate prepared above to prepare a piezoelectric ceramic composition.

That is, after the calcined nickel niobate was wet-milled for about 15 to 40 hours, and quantitatively added to lead oxide, titanium oxide, zirconium oxide, and manganese dioxide having a purity of 99.5% or more, the nickel niobate was prepared during preparation. The components were mixed with nickel niobate for about 15 to 40 hours using a ball mill in the same solvent used in the present invention, dried under an atmospheric atmosphere and calcined for about 1 to 3 hours in an electric furnace at a temperature of about 500 to 1200 ° C. Single phase piezoelectric ceramic composition powder is prepared.

The amount of lead oxide, titanium oxide and zirconium oxide added is represented by the following Chemical Formula 1

[Formula 1]

aPb (Ni _1/3 Nb _2/3 ) O ₃ -bPbZrO ₃ -cPbTiO ₃ + xMnO ₂

Where a is a molar ratio of 0.2 ≦ a ≦ 0.4, b is a molar ratio of 0.25 ≦ b ≦ 0.45, c is a molar ratio of 0.25 ≦ c ≦ 0.45 and x is 0.1 ≦ x ≦ 0.5 in weight percent of the total composition. Preferably, when the molar ratio of each coefficient of Chemical Formula 1 is outside this range, the physical properties required by the present invention cannot be obtained.

Manganese dioxide used in the present invention is added to impart an excellent piezoelectric voltage constant to the piezoelectric ceramic composition by changing the sinterability, microstructure, etc. of the ceramic sintered body through substitution with a specific element or penetration into the lattice. The amount of the added manganese dioxide may vary depending on the composition of the sintered body, but in order to obtain the effect required by the present invention, it is preferable to add the manganese dioxide so that the content of the manganese dioxide is 0.1 to 0.5% by weight based on the total amount of the piezoelectric ceramic composition.

After preparing the piezoelectric ceramic composition of the present invention, a specimen of the composition is prepared to measure physical properties of the ceramic composition.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

(Example 1)

Nickel oxide and niobium oxide having a purity of 99.5% or more were weighed in a molar ratio of 1: 1, added to an ethanol solvent, and ammonia water as a dispersant was added, mixed with a ball mill for 24 hours, and dried by grinding. The dried mixture was calcined in an alumina crucible having a temperature of 1100 ° C. for 3 hours to prepare nickel niobate powder. The nickel niobate powder thus prepared was subjected to a wet ball mill for about 24 hours, and the lead oxide, titanium oxide, zirconium oxide, and manganese dioxide were added to the composition shown in Table 1 below with a purity of 99.5% or more, followed by mixing and mixing. The ball mill was mixed and dried for 24 hours in an ethanol solvent and calcined at a temperature of about 800 ° C. for 2 hours.

The calcined ceramic composition powder was identified as Perovskite single phase through X-ray analysis and wet milling was performed for 24 hours to obtain an average particle size of 0.8 to 1.0 μm. After drying the wet compacted composition powder, the pressure molding was performed using a hydraulic press to a molding mold having a diameter of 20 mm, and a physical property measurement was performed by applying a pressure of about 2 ton / cm ^{2 using} a cold isostatic press or the like. A composition specimen was prepared.

The prepared specimen was uniformly covered with a powder having the same composition, and then placed in a sealed alumina crucible and kept at a temperature of about 1150 ° C. under a lead oxide atmosphere for about 4 hours to sinter the specimen. After grinding the sintered specimen to a thickness of about 1 mm with a polishing machine, removing foreign matter with an ultrasonic cleaner, and drying, the silver electrode was applied to both sides of the specimen and heat-treated at a temperature of about 590 ° C. for about 15 minutes to perform both sides of the specimen. Electrodes were formed. The electrode formed specimen was immersed in silicon oil having excellent electrical insulation and high specific heat and negligible temperature variation, and a piezoelectric property was applied to the specimen by applying a direct current of about 3 kV / mm to the silicon oil at a temperature of about 120 ° C. for about 10 minutes. Given. The piezoelectric specimen was heat treated at a temperature of 200 ° C. for about 5 hours to remove the aging phenomenon of the polarized specimen, and the piezoelectric voltage constant and the Curie temperature were measured in a conventional manner using the specimen from which the aging phenomenon was removed. And the results are shown in Table 2 below. In addition, the piezoelectric voltage constant and Curie temperature of the PZT three-component ceramic composition were also measured to compare the physical properties with the conventional piezoelectric ceramic composition, and the results are shown in Table 2 below.

(Example 2)

A piezoelectric ceramic composition was prepared in the same manner as in Example 1, except that the content of the composition was changed as shown in Table 1, and a specimen was prepared in the same manner as in Example 1, and the temperature was about 5 at 200 ° C. After the heat treatment for a time, the piezoelectric voltage constant and Curie temperature of the prepared specimens were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

(Examples 3 and 4)

A piezoelectric ceramic composition was prepared in the same manner as in Example 1, except that the content of the composition was changed as shown in Table 1, and a specimen was prepared in the same manner as in Example 1, and the temperature was about 10 ° C. at about 10 ° C. After the heat treatment for a time, the piezoelectric voltage constant and Curie temperature of the prepared specimens were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

Example 1 Example 2 Example 3 Example 4 a 0.2 0.2 0.4 0.4 b 0.35 0.45 0.25 0.35 c 0.45 0.35 0.35 0.25 MnO ₂ ^* 0.1 0.1 0.5 0.5

(*: Wt% relative to the total amount of the ceramic composition)

Example Conventional example One 2 3 4 PZT-5H Piezoelectric Voltage Constant 600 620 720 735 590 Curie temperature (℃) 290 285 220 210 195

As shown in Table 2, in Examples 1 and 2, the Curie temperature was improved by about 50% compared to the conventional example, and in Examples 3 to 4, the piezoelectric voltage constant was improved by about 20% compared to the conventional case. Able to know. In particular, the piezoelectric ceramic compositions prepared in Examples 1 to 4 significantly improved the aging phenomenon compared to the PZT tricomponent system (PZT_5H), which is a conventional composition, and the piezoelectric voltage constant did not decrease even when left for about 1 year at room temperature.

The method for producing a piezoelectric ceramic composition of the present invention can produce a piezoelectric ceramic composition which can be practically used for a voltage type acceleration sensor in which a piezoelectric voltage constant and a Curie temperature are high and aging is significantly prevented.

Claims (3)

A piezoelectric ceramic composition of formula 1 comprising manganese dioxide: [Formula 1] aPb (Ni _1/3 Nb _2/3 ) O ₃ -bPbZrO ₃ -cPbTiO ₃ + xMnO ₂ Wherein a is 0.2 ≦ a ≦ 0.4 in molar ratio, b is 0.25 ≦ b ≦ 0.45 in molar ratio, c is 0.25 ≦ c ≦ 0.45 in molar ratio and x is 0.1 ≦ x ≦ 0.5 in weight percent of the total amount of the composition. a) reacting and calcining nickel oxide and niobium oxide in the presence of a solvent and a dispersant to produce nickel niobate; And b) adding and calcining lead oxide, titanium oxide, zirconium oxide and manganese dioxide to the nickel niobate prepared above in the presence of a solvent Method for producing a piezoelectric ceramic composition of the formula 1 comprising a manganese dioxide comprising: [Formula 1] aPb (Ni _1/3 Nb _2/3 ) O ₃ -bPbZrO ₃ -cPbTiO ₃ + xMnO ₂ Wherein a is 0.2 ≦ a ≦ 0.4 in molar ratio, b is 0.25 ≦ b ≦ 0.45 in molar ratio, c is 0.25 ≦ c ≦ 0.45 in molar ratio and x is 0.1 ≦ x ≦ 0.5 in weight percent of the total amount of the composition. The method for producing a piezoelectric ceramic composition according to claim 2, wherein the solvent is one selected from the group consisting of ethanol, methanol, acetone and water, and the dispersant is ammonia water.