JPH0558729A - Piezoelectric ceramic composition - Google Patents

Abstract

PURPOSE:To obtain a large piezoelectric constant and to improve Curie temp. and temp. stability by incorporating a specified metal oxide into lead titanate- lead zirconate-nickel lead niobate-zinc lead niobate compsn. CONSTITUTION:One or more kinds of metal oxides selected from NiO, CuO, Bi2O3, WO3, SnO2, and CoO are added by 0.01-3mol% to the piezoelectric compsn. comprising PbTiO3, PbZrO3, Pb(Ni1/2Nb3/2)O3 and Pb(Zn1/3Nb2/3)O3. When this compsn. is expressed by aPbTiO3-bPbZrO3-cPb[(Ni1-xZnx)1/3Nb3/2]O3 ((a), (b), (c) are molar ratios satisfying (a+b+c)=1), the compsn. is in the area defined by three points A, B, C in the ternary composition diagram of figure 1 for 0.15<=x<=0.50, and defined by four points D-G in the composition diagram of figure 2 for 0.50<x<=0.85. Then the compsn. with addition of metal oxides is calcined at 600-900 deg.C for 1-6 hours, pulvelized, granulated and molded and then sintered at 1000-1400 deg.C for 1-10 hours.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a piezoelectric ceramic, and more particularly to a piezoelectric ceramic composition suitable as an actuator material.

[0002]

2. Description of the Related Art In recent years, piezoelectric actuators utilizing the piezoelectric effect of piezoelectric ceramics have been put to practical use in various fields such as precision positioning, relays and fans. The magnitude of mechanical displacement due to the piezoelectric effect of the piezoelectric actuator depends on the magnitude of the piezoelectric constant d of the piezoelectric ceramic, and the larger the value of d, the greater the amount of displacement.

As a piezoelectric ceramic composition having a large d, PbT
iO ₃ -PbZrO ₃ -Pb (Ni _1/3 Nb _2/3 )
O ₃ -Pb (Zn _1/3 Nb _2/3 ) O ₃ composition is used (for example, Japanese Patent Publication No. 49-4280), and has been improved according to various uses. Further, JP-A-2-258662 discloses a piezoelectric ceramic composition having a relatively high Curie temperature and a large d by studying the composition.

[0004]

When a piezoelectric ceramic is used as an actuator, it is required that the piezoelectric constant d be large in order to increase the displacement amount. At the same time, the stability of the displacement amount against temperature changes is important. Generally, piezoelectric constants such as piezoelectric constants and relative permittivities of piezoelectric ceramics increase with increasing temperature, and show maximum values at the Curie temperature. Therefore, it is important to raise the Curie temperature of the piezoelectric ceramic in order to make the temperature characteristics flat near room temperature for use as a piezoelectric actuator. Therefore,
As a piezoelectric actuator material, a piezoelectric ceramic composition having a larger d constant and a higher Curie temperature is desired.

[0005]

The present inventors have found that PbTiO 3
_{3 -PbZrO 3 -Pb (Ni 1/3 Nb} 2/3) O 3
-Pb (Zn _1/3 Nb _2/3 ) O ₃ As a result of various studies on additives to be added to the piezoelectric ceramic, the composition,
It has been found that the above problems can be solved by the kind and the amount of the additive.

That is, the present invention relates to lead titanate [PbTiO 3
₃ ], lead zirconate [PbZrO ₃ ], nickel lead niobate [Pb (Ni _1/3 Nb _2/3 ) O ₃ ], and zinc lead niobate [Pb (Zn _1/3 Nb _2/3 ).
O ₃ ], a composition of aPbTiO ₃ -bPbZr
_{O 3 -cPb [(Ni 1-} X Zn X) 1/3 N
b _2/3 ] O ₃ (where a, b, and c are mole fractions,
a + b + c = 1), the composition is (i) 0.13 ≦ X ≦ 0.50 in the three-component composition diagram. It is surrounded by the line connecting the following points and these three points. Within the range, A (a = 0.275, b = 0.275, c = 0.450) B (a = 0.416, b = 0.384, c = 0.200) C (a = 0.374) , B = 0.176, c = 0.450) (ii) When 0.50 <X ≦ 0.85 On the line connecting the following points and within the range surrounded by these four points, D (a = 0 .275, b = 0.275, c = 0.450) E (a = 0.416, b = 0.384, c = 0.200) F (a = 0.374, b = 0.176, c = 0.450) G (a = 0.286 , b = 0.134, the composition in the c = 0.580), NiO, CuO , Bi 2 O 3, W
A piezoelectric ceramic composition containing 0.01-3 mol% of one or more kinds of metal oxides selected from the group consisting of O ₃ , SnO ₂ , and CoO.

The present invention will be described in detail below.

The additives in the present invention include NiO and C.
_uO, a Bi ₂ O _3, WO _3, a metal oxide comprising SnO 2, CoO, the composition thereof is as described above,
0.01-3 mol% is added. Addition amount is 0.01m
If it is less than ol%, the effect of improving the properties is not remarkable, and if it exceeds 3 mol%, further improvement of the properties is not observed and the Curie point is lowered to lose the usefulness. These additives may be added alone or in combination of two or more.

As the raw material powder used for producing the piezoelectric ceramic composition of the present invention, a compound containing each metal element constituting the obtained composition, such as an oxide or a carbonate, may be used. These compounds are prepared so as to have a desired composition, mixed with, for example, a ball mill, and the mixture is heat treated. The heat treatment at this time can be performed at a relatively high temperature without performing calcination, but it is preferable to perform the calcination at a higher temperature after calcination in order to obtain a composition having higher properties. Is desirable. The calcination performed here is, for example, at 600 to 900 ° C. for about 1 to 6 hours, and the obtained calcinated product is pulverized and sized to obtain powder. The powder thus obtained is formed into a desired shape by a die press, a rubber press, or the like and sintered to obtain a piezoelectric ceramic. The sintering at this time is, for example, 1 to 1000 to 1400 ° C.
It may be held for about 10 hours. The atmosphere at this time is not particularly limited, but the atmosphere can be performed.

The additives in the piezoelectric ceramic composition of the present invention may be added from the beginning as described above, or may be calcined, pulverized and sized to obtain lead titanate-lead zirconate-nickel. -Lead niobate-zinc-lead niobate composition powder may be mixed and added.

[0011]

The piezoelectric ceramic composition of the present invention has a piezoelectric constant d.
Since it has a large Curie temperature and a high Curie temperature, it is extremely useful as a material for an actuator that requires a large amount of displacement and temperature stability.

[0012]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1-14, Comparative Example 1-2 As starting materials, PbO, TiO ₂ , ZrO ₂ , NiO,
ZnO, Nb ₂ O ₅ and additives were weighed so as to have the composition shown in Table 1, wet-mixed with a ball mill, dried, and calcined in the air at 900 ° C. for 2 hours. The obtained calcined product was again wet-milled with a ball mill to obtain a target composition powder. This powder is molded into pellets and
Time sintering was performed.

The obtained sintered body has a diameter of 20 mm and a thickness of 1
mm disk shape, length 12 mm, width 3 mm, thickness 1 mm
Was cut into strips, and silver electrodes were baked on both sides in the thickness direction. A polarization voltage was applied to the measurement sample by applying a DC voltage of 2 kv / mm for 5 minutes in silicon oil at 120 ° C. After being left in the air at 80 ° C. for 24 hours, the piezoelectric constant d ₃₁ , the electromechanical coupling coefficient Kp, and the relative dielectric constant ε ^T ₃₃ / KHz at 1 KHz were measured using a vector impedance meter.
ε ₀ and Curie temperature Tc were measured. The results are shown in Table 2.

As is apparent from Table 2, d _{31 of the} example
The absolute value of each is larger than that of the comparative example,
Further, it can be seen that the value of Tc is almost the same as that of the comparative example and shows a good value.

[0016]

[Table 1]

[0017]

[Table 2]

[Brief description of drawings]

FIG. 1 aPbTiO which is one component of the composition of the present invention
_{3 -bPbZrO 3 -cPb [(Ni 1} -X Zn X)
_{In 1/3} Nb _2/3 ] O ₃ , X is 0.15 ≦ X ≦
It is a figure which shows the composition range in case of 0.50.

FIG. 2 aPbTiO, a component of the composition of the present invention
_{3 -bPbZrO 3 -cPb [(Ni 1} -X Zn X)
_{In 1/3} Nb _2/3 ] O ₃ , X is 0.50 <X ≦
It is a figure which shows the composition range in case of 0.85.

Claims (1)

[Claims] 1. Lead titanate [PbTiO ₃ ], lead zirconate [PbZrO ₃ ], nickel lead niobate [Pb
(Ni _1/3 Nb _2/3 ) O ₃ ], and lead zinc niobate [Pb (Zn _1/3 Nb _2/3 ) O ₃ ], aPbTiO ₃ -bPbZrO ₃ -cPb
When expressed as [(Ni _1-X Zn _X ) _⅓ Nb _2/3 ] O ₃ (where a, b, and c are molar fractions, and a + b + c = 1), the three-component system composition In the figure, when the composition is (i) 0.15 ≦ X ≦ 0.50, on the line connecting the following points and within the range surrounded by these three points, A (a = 0.275, b = 0.275) , C = 0.450) B (a = 0.416, b = 0.384, c = 0.200) C (a = 0.374, b = 0.176, c = 0.450) (ii) When 0.50 <X ≦ 0.85 On the line connecting the following points and within the range surrounded by these four points, D (a = 0.275, b = 0.275, c = 0.450) E (A = 0.416, b = 0.384, c = 0.200) F (a = 0.374, b = 0.176, c = 0.450) G (a = 0.28 , B = 0.134, the composition in the c = 0.580), NiO, CuO , Bi 2 O 3, W
A piezoelectric ceramic composition containing 0.01-3 mol% of one or more kinds of metal oxides selected from the group consisting of O ₃ , SnO ₂ , and CoO.