JPH0541549A - Piezoelectric porcelain materials - Google Patents

Abstract

PURPOSE:To minimize the deterioration of piezoelectric properties and enhance an electric machine coupling factor even when thermal impact is applied by allowing a 100g of basic composition which satisfies a specific expression to contain Mn as a sub-component at a rate of 0.8 to 1.5g. CONSTITUTION:The piezoelectric magnetic materials which are used as a piezoelectric vibrator or films are generally given by the following expression where XPb (Sn0.5Sb0.5) O3-YPbTiO3-(I-X-Y)PbZrO3. The materials are given by (X +Y)<1 in the expression and satisfy 0.01<=X<=0.20 and 0.30<=Y$0.70. 100g of this basic composition is arranged to contain Mn as a sub-component at the rate of 0.8 to 10.5g. This construction makes it possible to minimize the deterioration of piezoelectric properties even when thermal impact is added, say, provide a piezoelectric resonator which has large piezoelectric properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric ceramic material, and more particularly to a piezoelectric ceramic material used for piezoelectric vibrators or filters.

[0002]

2. Description of the Related Art Lead zirconate titanate (Pb (Ti, Zr) O ₃ )
Is a porcelain composition which has been widely known as a piezoelectric ceramic material. The material used for the piezoelectric resonator is required to have large piezoelectric characteristics such as electromechanical coupling coefficient (kt) and mechanical quality coefficient (Q _mt ), and the operating temperature range of the resonator is expanded (-40 ° C). ˜80 ° C.), it is required that the deterioration of these piezoelectric characteristics is small with respect to the temperature change. Generally, as a piezoelectric ceramic material, PbTiO ₃ -PbZrO ₃ (P
It is known that ZT) -based porcelain exhibits excellent piezoelectric characteristics, and has been used as a material for piezoelectric buzzers, frequency filters, ignition elements and the like.

Conventionally, as a third component in a PZT system porcelain
The material containing Pb (Sn _0.5 Sb _0.5 ) O ₃ has a rate of change of electromechanical coupling coefficient (kt) of 5 even when forced to heat aging at 150 ° C.
%, Which is considerably small, and is known as a material having excellent temperature stability (Japanese Patent Publication No. 55-18059).

[0004]

By the way, a piezoelectric ceramic material having a small deviation in oscillation frequency and high reliability is required for a piezoelectric resonator. The most severe condition of the reliability test is a thermal shock test in which a thermal shock of −40 ° C. to 80 ° C. is given, and the piezoelectric characteristics are deteriorated by the thermal shock, and the oscillation frequency is largely deviated. Often becomes.

Among conventional materials, for example, Japanese Patent Publication No. 55-1
Pb (Sn _a Sb _1-a ) O ₃ -PbTiO ₃ -PbZr disclosed in Japanese Patent No. 8059
Even in the O ₃ system, there is a problem that the piezoelectric characteristics are deteriorated by thermal shock and the oscillation frequency shifts.

The present invention has been invented in view of the above problems, and a piezoelectric ceramic material having a small deterioration of piezoelectric characteristics even when a thermal shock is applied and a high electromechanical coupling coefficient, that is, a large piezoelectric characteristic is provided. It is intended to be provided.

[0007]

In order to achieve the above object, the piezoelectric ceramic material according to the present invention has a general formula of XPb (Sn _0.5 Sb
_{0.5) O 3 -YPbTiO 3 - (} 1-X-Y) PbZrO 3 ( proviso X +
Y <1), and 0.01 ≦ X ≦ O. 20, 0.30
With respect to 100 g of the basic composition satisfying ≦ Y ≦ 0.70,
It is characterized by containing Mn as an accessory component in a ratio of 0.8 to 1.5 g.

[0008]

The thermal shock test can be divided into a temperature raising process of raising the temperature from -40 ° C to 80 ° C and a temperature lowering process of lowering the temperature from 80 ° C to -40 ° C. As shown in FIG. 1, particularly in the temperature-decreasing process, as the spontaneous polarization of the piezoelectric body increases, charges accumulate near the surface of the piezoelectric body, and this charge is depolarized because a voltage is applied in the opposite direction to the polarization direction. cause. As a result, the piezoelectric characteristics deteriorate and the oscillation frequency shifts. In order to prevent deterioration, it is necessary to reduce the resistance of the piezoelectric body in order to quickly alleviate the accumulated charge.

As shown in FIG. 2, when the resistivity of Pb (Sn _0.5 Sb _0.5 ) O ₃ , PbTiO ₃ , and PbZrO ₃ systems, which are materials according to the present invention, was examined, it was found that Pb (Pb Sn _0.5 Sb _0.5 )
It was found that the resistivity decreases as the amount of O ₃ decreases.

Further, as shown in FIG. 3, due to the reduction of the resistivity, the deviation of the oscillation frequency after the thermal shock was reduced.

According to the above configuration, the general formula is XPb
(Sn _0.5 Sb _0.5 ) O ₃ —YPbTiO ₃ — (1-X—Y) PbZrO ₃ (where X + Y <1), and 0.01 ≦ X ≦ O. 20,
100 g of basic composition satisfying 0.30 ≦ Y ≦ 0.70
On the other hand, by containing Mn as a sub-component in a ratio of 0.8 to 1.5 g, the deterioration of piezoelectric characteristics is small even when a thermal shock is applied, and the electrical coupling coefficient (kt) is high. For example, a piezoelectric resonator having large piezoelectric characteristics can be obtained.

The reason why the substitution amount range of Pb (Sn _0.5 Sb _0.5 ) O ₃ is limited to 1 to 20 mol% is that if it exceeds 20 mol%, the resistivity becomes remarkably large and the reliability is poor. Conversely 1
If it is less than mol%, the evaporation of PbO 2 will be so intense that a dense sintered body cannot be obtained. If PbTiO ₃ is less than 30 mol% or more than 70 mol%, the electromechanical coupling number (kt) is 30% or less, and the piezoelectric characteristics are significantly deteriorated. Similarly M
The reason why the amount of n is limited to 0.8 to 1.5 g is that the piezoelectric characteristics are deteriorated even at 0.7 g or less and 1.6 g or more.

[0013]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of piezoelectric ceramic materials according to the present invention will be described below. Pb ₃ O ₄ , Sn as raw materials
Various oxides of O ₂ , Sb ₂ O ₃ , Nb ₂ O ₅ , ZrO ₂ , TiO ₂ , and MnCO ₃ were used. The raw materials are not limited to these, and other compounds can be used as long as they finally become the above oxides. These raw materials were weighed and blended so as to have the composition shown in Table 1, and wet mixed in a ball mill for 24 hours. The mixed raw materials were dried and then calcined in the temperature range of 700 to 950 ° C. Next, an appropriate amount of organic binder was added and dry-mixed, and the mixture was passed through a mesh container for sizing. The powder obtained in this way is 20 × 30 at a pressure of 1000-1500 kg / cm ^2.
It was molded into a plate shape of × 1 mm and was fired in the temperature range of 1200 to 1300 ° C to obtain a piezoelectric ceramic. This piezoelectric ceramic sintered body was processed into 3.5 x 6 x 0.2 mm, and the diameter of 1
After making the electrode of mm by vapor deposition of silver, it is polarized.
A thickness longitudinal vibration mode resonator was produced.

The characteristics of the resonator are measured by an impedance analyzer, and the relative permittivity (ε ₃₃ ^T / ε ₀ ), mechanical quality factor (Q _mt ), and electromechanical coupling factor (kt) are calculated by the following equations. did.

[0015]

[Equation 1]

[0016]

[Equation 2]

[0017]

[Equation 3]

Further, in order to evaluate the thermal shock resistance, the change of the oscillation frequency after repeating 100 cycles of thermal shock (-40 minutes at -40 ° C. → 5 minutes at room temperature → 30 minutes at 85 ° C. → 5 minutes at room temperature). The rate (Δf _osc ) was determined. Table 1 shows the piezoelectric characteristics thus obtained.

[0019]

[Table 1]

[0020]

[Table 1-2]

[0021]

[3 in Table 1]

[0022]

[Table 2]

[0023]

[Table 2-2]

[0024]

[3 in Table 2]

In Table 1, those marked with * are outside the scope of the present invention, and the others are within the scope of the present invention. As is clear from Table 1 and Table 2, those within the range of the present invention can obtain a high electromechanical coupling coefficient (kt) and have a change rate (Δf _osc ) of the oscillation frequency after 100 cycles of thermal shock. It can be seen that it is small and has excellent temperature stability.

On the other hand, in the comparative example, sample numbers 29 and 3
No. 0 did not oscillate, Sample Nos. 47 and 48 had difficulty in polarization, and Sample No. 1 had difficulty in sintering.

In another comparative example, the electromechanical coupling coefficient (kt) is 30% or less, which means that the piezoelectric characteristics are small.

As described above, in the piezoelectric ceramic material according to the above embodiment, a resonator having a large electromechanical coupling coefficient (kt), which is a piezoelectric characteristic, and having a small deterioration of the piezoelectric characteristic even when a thermal shock is applied, is manufactured. It can be used as an oscillating device having stable characteristics in a wide range of −40 ° C. to 80 ° C.

[0029]

As described in detail above, in the piezoelectric ceramic material according to the present invention, the general formula is XPb (Sn _0.5 Sb _0.5 ) O ₃ -YPb
TiO ₃ − (1-XY) PbZrO ₃ (where X + Y <1), and 0.01 ≦ X ≦ O. 20, 0.30 ≦ Y ≦ 0.7
By containing 0.8 to 1.5 g of Mn as an accessory component with respect to 100 g of the basic composition satisfying 0, deterioration of piezoelectric characteristics is small even when a thermal shock is applied, and the electric coupling coefficient is small. It is possible to manufacture a piezoelectric resonator having a high (kt), that is, a large piezoelectric characteristic.

[Brief description of drawings]

FIG. 1 is a diagram showing a piezoelectricity variation mechanism during thermal shock.

FIG. 2 is a graph showing a reduction in resistance by reducing the amount of Pb (Sn _0.5 Sb _0.5 ) O ₃ .

FIG. 3 is a graph showing improvement in thermal shock resistance due to lower resistance.

Claims (1)

[Claims] 1. The general formula is XPb (Sn _0.5 Sb _0.5 ) O ₃ —YPbTiO ₃
- represented by (1-X-Y) PbZrO 3 ( provided that X + Y <1), 0.01 ≦ X ≦ O. 20, 0.30 ≦ Y ≦ 0.70
To 100 g of the basic composition satisfying
A piezoelectric ceramic material containing n in a proportion of 0.8 to 1.5 g.