JPH07157315A - Production of piezoelectric ceramic composition - Google Patents

Abstract

PURPOSE:To form a homogeneous perovskite phase and obtain a compsn. having a high electromechanical coupling factor by previously mixing and burning components except Pb and Me when a piezoelectric ceramic comspn. represented by the general formula (Pb1-xMex)-(TiyZrzB1-y-z)O3 is produced. CONSTITUTION:Components except Pb and Me, that is, B-site components are previously mixed and burnt at 800-1,200 deg.C and the burnt components are mixed with PbO and Me and burnt. In the formula, Me is one or more among Sr, Ca and Ba, B is one or more among (Mg1/3Nb2/3), (Ni1/3Mb2/3), (Sn1/3Nb2/3), (Zn1/3Nb2/3), (Co1/3Nb2/3), (Mn1/3Nb2/3) and (Fe1/2Nb1/2) and 0<=x<=0.2. By this method, a selective reaction of Pb with Nb as a B-site component in a burning process can be prevented and a homogeneous perovskite phase is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a piezoelectric filter, an oscillator,
The present invention relates to a method for producing a piezoelectric ceramic composition used for an actuator or the like.

[0002]

2. Description of the Related Art In recent years, as the amount of communication information such as video signals and audio signals has increased, the propagation frequency has become wider. In this way, due to the widening of the propagation frequency, the piezoelectric filter element is required to have a high electromechanical coupling coefficient.

As a piezoelectric ceramic composition, Pb has been conventionally used.
Ti _x Zr _y (Mg _1/3 Nb _2/3 ) z O ₃ ternary system, P
bTi _A Zr _B (Zn _1/3 Nb _2/3 ) _C (Sn _1/3 Nb
_2/3 ) There are piezoelectric ceramic compositions composed of _D O ₃ quaternary composition. In these conventional piezoelectric ceramic compositions, raw materials of all components are simultaneously mixed, then calcined and pulverized to produce powder of the piezoelectric ceramic composition.

[0004]

However, in the conventional manufacturing method, since all the components are mixed and calcined at the same time, the sintering reaction of the starting materials does not occur at the same time in the calcining process, and PbO and Nb ₂ O ₅ are not simultaneously generated. Only the selective reaction occurs. Therefore, a pyrochlore phase is generated as a crystal phase other than the perovskite phase, which can be expressed as ABO _3, and remains after firing. Therefore, although some characteristics can be obtained, there is a problem that it is difficult to sufficiently increase the electromechanical coupling coefficient (kr) which is a piezoelectric characteristic.

In view of the above problems of the prior art, the present invention provides an excellent piezoelectric ceramic composition capable of producing a homogeneous perovskite phase and having a sufficiently high electromechanical coupling coefficient (kr). An object is to provide a method for manufacturing a product.

[0006]

The first invention of the present application is represented by the general formula (Pb _1-x Me _x ) (Ti _y Zr _z B _1-yz ) O ₃ , where B is (Mg _1/3 Nb _2/3 ), (Ni _1/3 Nb
_2/3 ), (Sn _1/3 Nb _2/3 ), (Zn _1/3 N
b _2/3 ), (Co _1/3 Nb _2/3 ), (Mn _1/3 N
b _2/3 ) and (Fe _1/2 Nb _1/2 ), Me is at least one element selected from Sr, Ca and Ba, and x is 0 ≦ x ≦ 0.
A method for producing a perovskite-type piezoelectric ceramic composition as described in 2, wherein only components other than Pb and Me (hereinafter simply referred to as B-site components) are mixed in advance, and 800 to 12
The method is characterized by including a step of calcination at 00 ° C., a step of mixing B site component preliminarily mixed and calcined, a step of mixing PbO and Me component, and calcination.

The second invention of the present application is (Pb _1-x Me _x )
(Ti _y Zr _z ) O ₃ (where Me is at least one element selected from Sr, Ca and Ba, and x
Is 0 ≦ x ≦ 0.2) as a main component and Nb as a sub-component.
A method for producing a perovskite type piezoelectric ceramic composition containing 1 mol% or more of atoms, which comprises premixing only a B site component and calcining at 800 to 1200 ° C, and premixing,
It is characterized by including a step of mixing and calcining the calcined B-site component and the PbO and Me components.

Preferably, the auxiliary component is 0.1 to 5.0.
A weight percentage of at least one selected from MnO ₂ , Cr ₂ O ₃ and CoO is mixed with the PbO and Me components.

[0009]

According to the present invention, only the B-site component is premixed and calcined at 800 to 1200 ° C., and then PbO and M are added.
Since the e component and the B site component are mixed and calcined, it is possible to prevent Pb from selectively reacting with Nb of the B site component in the calcining step, and a homogeneous perovskite phase is generated, and therefore, the electric perovskite phase is generated. It is possible to produce a piezoelectric ceramic composition having a stable mechanical coupling coefficient (kr) and the like.

[0010]

EXAMPLE An example of the present invention will be described in detail below.

As a starting material, P which is chemically high in purity is used.
bO, SrCO ₃ , BaCO ₃ , TiO ₂ , ZrO ₂ ,
ZnO, SnO ₂ , MgO, NiO, CoO, Nb ₂ O
₅ , MnO ₂ and Cr ₂ O ₃ were prepared.

First, in the first step, B site components of TiO ₂ , ZrO ₂ , ZnO, SnO ₂ , MgO,
After correcting the purity of NiO, CoO, and Nb ₂ O ₅ , they were weighed so as to have the composition of each sample shown in Table 1, Table 2, and Table 3. These weighed materials were placed in a polyethylene ball mill, 5 mmφ stabilized zirconia balls and pure water were added, and mixed for 16 hours. The slurry obtained by mixing is dried, put in an alumina crucible,
It was calcined at 0 ° C. for 2 hours to obtain a calcined powder of B site component.

Next, as a second step, PbO, SrC
After correcting the purity of O ₃ and BaCO _3, the calcined powder of B site component and MnO ₂ and C of additives were corrected.
r ₂ O ₃ and CoO were weighed so as to have the composition of each sample shown in Table 1, Table 2 and Table 3. These weighed materials were mixed for 16 hours by the above-mentioned ball mill. The slurry obtained by mixing is dried and put in an alumina crucible.
It was calcined at 0 ° C for 2 hours. The calcined powder was pulverized by the ball mill for 16 hours and dried to obtain a calcined powder of the piezoelectric ceramic composition.

A piezoelectric ceramic was produced using the calcined powder produced as described above.

For the production of the piezoelectric ceramic, 7% by weight of a 5% aqueous solution of polyvinyl alcohol as a binder was added to the calcined powder of the piezoelectric ceramic composition described above and mixed, and then granulated through a 32 mesh sieve and at 100 MPa. Diameter 13mm,
It was press-formed into a disk shape having a thickness of about 0.7 mm. After the molded body is heated at 600 ° C for 2 hours to incinerate the binder, the molded body is put in a magnesia porcelain container and the lid is closed.
It was held at ° C for 2 hours and baked.

As a comparative example, a sample in which the PbO and Me components, the B site component, and the additives were simultaneously mixed and calcined without precalcining the B site component was also prepared.

Au vapor-deposited electrodes were applied to both sides of the fired body, and 16
A polarization treatment was performed by applying a DC electric field of 3 to 4 kV / mm between both electrodes in insulating oil at 0 ° C. for 30 minutes. Various characteristics were measured using this sample.

The electromechanical coupling coefficient (kr) was obtained by the resonance-antiresonance method using an impedance analyzer. The results are shown in Table 1, Table 2 and Table 3.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

As can be seen from Table 1, Table 2 and Table 3,
According to the method of manufacturing the piezoelectric ceramic composition of this example, the electromechanical coupling coefficient (kr) can be sufficiently increased.

[0023]

As described above, according to the method for producing a piezoelectric ceramic composition of the present invention, the steps of premixing and calcining only the B site component and the premixed and calcined B site component and Pb are carried out.
Since a step of mixing O and Me components and calcining is included, a homogeneous perovskite phase is generated, and a piezoelectric ceramic composition having an excellent electromechanical coupling coefficient (kr) and the like can be manufactured.

Claims (3)

[Claims] 1. The general formula (Pb _1-x Me _x ) (Ti _y Zr
_z B _1-yz ) O ₃ and B is (Mg _1/3 N
b _2/3 ), (Ni _1/3 Nb _2/3 ), (Sn _1/3 N
b _2/3 ), (Zn _1/3 Nb _2/3 ), (Co _1/3 Nb _2/3 ), (Mn
_1/3 Nb _2/3 ), and (Fe _1/2 Nb _1/2 ), Me is at least one element selected from Sr, Ca and Ba, and x is 0 A method for producing a perovskite-type piezoelectric ceramic composition such that ≦ x ≦ 0.2, in which only components other than Pb and Me are mixed in advance,
The process of calcination at 1200 ° C and P mixed and calcined in advance
A method for producing a piezoelectric ceramic composition, comprising a step of mixing components other than b and Me and PbO and Me components and calcining. 2. (Pb _1-x Me _x ) (Ti _y Zr _z ) O
₃ (However, Me is at least one element selected from Sr, Ca and Ba, and x is 0 ≦ x ≦ 0.2)
A method for producing a perovskite-type piezoelectric ceramic composition containing, as a main component, Nb atoms in an amount of 1 mol% or more as a sub-component, wherein only components other than Pb and Me are mixed in advance,
The process of calcination at 1200 ° C and P mixed and calcined in advance
A method for producing a piezoelectric ceramic composition, comprising a step of mixing components other than b and Me and PbO and Me components and calcining. 3. As a minor component, at least one selected from 0.1 to 5.0% by weight of MnO ₂ , Cr ₂ O ₃ and CoO is mixed together with PbO and Me components. Item 3. A method for producing the piezoelectric ceramic composition according to Item 1 or 2.