JPS6046834B2 - Piezoelectric porcelain composition - Google Patents

Description

[Detailed description of the invention] The present invention is Pb(MnlI3Me213)O.

-PbTi03-PbZr03 (Me is Nb, T
uranium oxide (U.O0) or magnesium oxide (Mg
The piezoelectric porcelain is characterized by containing O),
The objective is to provide a piezoelectric ceramic composition for a ceramic filter that has significantly improved stability of properties, particularly temperature changes in mechanical quality factor (Qm). The basic characteristics for practically evaluating the piezoelectricity of piezoelectric materials are the electromechanical coupling coefficient and the mechanical quality coefficient.

When a piezoelectric material is applied to a ceramic bandpass filter, it is necessary to have an electromechanical coupling coefficient corresponding to the width of the passband.

In other words, in order to widen the bandwidth, the electromechanical coupling coefficient must be increased. On the other hand, the mechanical quality factor is desired to be as large as possible in order to reduce insertion loss in the passband. By the way, when constructing a ceramic filter such as a ladder-type 455KH2 intermediate frequency filter, it is usually made by combining four or more ceramics of two or three types with different electrode structures, dimensions, and thicknesses.

In this case, if the ceramic is ideally manufactured, that is, if the piezoelectric and dielectric constants of the same type of ceramic are exactly the same without variations, then the higher Qm is, the steeper the rise characteristic of the passband will be. Yes, it is possible to construct very good filters. However, in general, the piezoelectric and dielectric constants of ceramics vary with temperature and manufacturing variations are unavoidable. In this case, when Qm is high, the passband characteristics are disturbed, which is a practical problem. Therefore, it has been found that by adjusting the temperature change of Qm and reducing the value of Qm to some extent, it is possible to keep the insertion loss within the standard without causing any disturbance in the passband characteristics. Therefore, the present invention has developed a three-component piezoelectric composition, Pb(Mnll3Me2l), which has excellent temperature and aging characteristics and a high Qm value.
3) of 03-PbTiO3-P.

(However, Me is Nb, Ta, Sb) based on uranium oxide (U)
3O8) or magnesium oxide (MgO), and according to the present invention, it is possible to reduce the temperature change in Qm and reduce Qm, and a material that is practical as a material for ceramic filters can be obtained. Next, a detailed explanation will be given with reference to examples. Examples Starting materials for obtaining the porcelain of the present invention are lead oxide (PlO), manganese carbonate (MnCO3), niobium oxide (Nh.O5), tantalum oxide (Ta2O5), antimony oxide (Sb2O3), titanium oxide (TiO2), Each powder of zircon oxide (ZrO2), uranium oxide (U3O8), and magnesium oxide (MgO) was used.

Here, MncO3 was converted into MnO to obtain the required amount.

A predetermined amount of each powder was weighed, mixed with pure water in a ball mill, and the mixed powder was prefired at 900° C. for 1 hour. After crushing, the 30y powder was crushed to a diameter of 2 with a pressure of 700k9/Clt.
- It was molded into a cylinder.

Next, it was fired at 1230°C to 1300°C for 1 hour. After cutting the obtained porcelain to 0.37T0f1, a silver electrode was baked onto it. Then 1000V to 1500 at 100℃
A DC voltage of V was applied for 60 minutes to piezoelectrically activate it.
Electromechanical coupling coefficient of radial vibration (Kr) after leaving between two dishes
and mechanical quality coefficient (Qm) were measured.

This measurement followed the method of the I,R,E standard circuit.

Representative examples of the results obtained are shown in Table 1.

The temperature change rate of Qm is -20℃ and + with 20℃ as the standard.
The values measured between 60°C and 60°C are shown in (%).
Kr and Qm are average values of 1-loss sample.

As is clear from Table 1, if an appropriate amount of uranium oxide (U3O8) or magnesium oxide (MgO) is included as a subcomponent, Qm can be reduced, and the material has been improved to be practical for ceramic filters. There is.

That is, the present invention provides Pb(Mnll3Me2l3)0
3 [Me represents Nb, Ta, Sb] -PbT
Pb(Mnl/3r!4e213)JlyZr2O3
[However, when expressed as x+y+z=1.00], X, y
, z are within a limited composition range, and uranium oxide (U3O8) is contained as a subcomponent from 0.1 wt% to 0.
．． 5 Wt%, or 0.5 Wt% of magnesium oxide (MgO).
It is characterized by containing 5 wt%.

In addition, if Kr is low outside the basic composition range, is it impractical?Q
The value of m is low and is not a target of the present invention.

Claims (1)

[Claims] 1 Pb(Mn1/3Me2/3)O_3 [However, Me
represents Nb, Ta, Sb]-PbTiO_3-Pb
A three-component piezoelectric ceramic composition consisting of ZrO_3 was
n1/3Me2/3)_xTi_yZr_zO_3 [however, x+y+z=1.00], x, y, z
are within the limited composition ranges of 0.03≦x≦0.20, 0.30≦y≦0.60, 0.20≦z≦0.67, respectively, and uranium oxide (U_3O_8) is contained as a subcomponent at 0.0. 1wt% to 0.5wt%
A piezoelectric porcelain composition characterized by containing. 2 Pb(Mn1/3Me2/3)O_3 [However, Me
represents Nb, Ta, Sb]-PbTiO_3-Pb
A three-component piezoelectric ceramic composition consisting of ZrO_3 was
n1/3Me2/3)_xTi_yZr_zO_3 [however, x+y+z=1.00], x, y, z
are within the limited composition range of 0.03≦x≦0.20, 0.30≦y≦0.60, and 0.20≦z≦0.67, respectively, and magnesium oxide (MgO) is contained as a subcomponent at 0.0. 5wt% to 1.5wt%
A piezoelectric porcelain composition characterized by containing.