JPH02303172A - Piezoelectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric porcelain composition with good electrical temperature characteristics and with small deformation due to baking by using a land titanate zirconate containing a solid solution of Pb(MnalphaSb1-alpha)O3 as a third component. CONSTITUTION:This composition is composed of a three-component-system solid solution having a composition which is represented by a formula of X.Pb(MnalphaSb1-alpha)O2-Y.PbZrO3-Z.PbTiO3 (in this formula, X, Y, Z and alpha are mole ratios of individual components and satisfy X+Y+Z=1.00 and 0.4/3<=alpha<1.5/3. However, alpha=1/3 is excluded) and which is included within a range surrounded by a polygon ABCDE whose apexes are points A, B, C, D and E. At least one kind selected from a group composed of CoO, NiO, Fe2O3 and SnO2 is added as an additive at 0.05 to 0.9wt.%.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to piezoelectric ceramic compositions, specifically materials for piezoelectric ceramic elements such as powerful ultrasonic vibrators, filters, oscillators, and ultrasonic probes. The present invention relates to a piezoelectric ceramic composition useful as a piezoelectric ceramic composition.

(Prior Art) Various improvements have been made to lead zirconate titanate porcelain, which has heretofore been known as a typical piezoelectric material, and piezoelectric porcelain compositions having characteristics depending on the purpose of use have been proposed. For example, a part of pb of Pb(Zr,Ti)Os is B a, S
rs Substituted with a divalent element such as Ca, or Pb(Ti, Zr)○, with Pb(Mn) as a third component.
+z+5btz3)○5, Pb(Mr++/zSb+z
t) 0, or P b(NbαS bt 3a M
n*a I) Solid solution of 03 (Special Publication No. 46-1)
Japanese Patent Publication No. 5979, Japanese Patent Publication No. 47-43513, Japanese Patent Publication No. 11798-1982) have been developed and put into practical use.

(Problems to be Solved by the Invention) These piezoelectric ceramic compositions have excellent properties in either the electromechanical coupling coefficient (Kp) or the mechanical quality coefficient (Qm), which is used to evaluate the quality of the piezoelectric properties. However, there was a problem in that the deformation caused by firing was large. This problem is particularly severe when attempting to produce a product that satisfies both Kp and Qm properties at the same time, and it has been virtually impossible to obtain a fired product that satisfies both properties. For example, pb(Mn,/sS btz3)03-P bZ r
In the conventional composition consisting of o 3-P bT i○3, its properties become better near the phase boundary (MPB), but K
When trying to obtain the characteristics of p=50% and Qm=2000, the warpage and waviness caused by firing are extremely large, making it extremely difficult to put it into practical use, and furthermore, there are problems such as extremely poor temperature characteristics.

Therefore, the main object of the present invention is to obtain a piezoelectric ceramic composition that has excellent electrical properties and temperature properties and is less deformed by firing.

Another object of the present invention is to obtain a piezoelectric porcelain composition having both a large electromechanical coupling coefficient and a large mechanical quality coefficient.

Another object of the present invention is to obtain a piezoelectric ceramic composition that generates little heat even when driven at high voltage and high power and has excellent durability.

(Means for Solving the Problems) The present invention provides lead zirconate titanate with pb (MnaSb,
-α)O:+(0,4/3<a<1.5/3゜However, α
-1/3 excluded. ) is dissolved in solid solution at a predetermined ratio.

That is, the piezoelectric ceramic composition according to the present invention has X-Pb
(MnαSb+-α)O; YPbZrO3Z・Pb
TiOs (where X, Y, Z and α are the mole fractions of each component, x+y+z=t, oo, respectively.

0.4/3≦α≦1.5/3 is satisfied. However, α-1
/3 is excluded. ) and whose vertices are points A, B, C, D, and E of the following composition in Figure 1:
It is characterized by consisting of a ternary solid solution having a composition within the range surrounded by E.

X Y Z A O,010,200,79 B O,010,970,02 CO,030,970,00 D O,200,800,00 E O,200,200,60 The present invention also provides piezoelectric properties In order to further improve the performance, Pb (MncrSb
, -α)03(0,4/3<α<1.5/3゜However, α
-1/3 excluded. ) at a predetermined ratio, and at the same time, CooSNip as an additive.

At least one selected from the group consisting of Fe, 03 and SnO is contained in an amount of 0.05 to 0.9% by weight.

(Function) The reason why the composition range of the piezoelectric ceramic composition according to the present invention is limited to the above range and the effects of these components are as follows.

Pb(MnaS)g-a)03 is added mainly to improve piezoelectric properties and at the same time to suppress deformation during firing, but when its molar fraction X is 0.01,
Complete firing is difficult, and the piezoelectricity is hardly improved, or even if it is improved, it is not to the extent that it can be put to practical use.
Moreover, if it exceeds 0.20, it becomes extremely difficult to completely fire the ceramic, and the piezoelectricity of the resulting porcelain will not be of a practical level, so it was set in the above range.

In addition, if α is outside the above range, the piezoelectricity will deteriorate extremely and it will not be suitable for practical use, so the value of α should be 0.4/3 to 1.5/3 (
However, α-1/3 is excluded. ).

If the molar fraction of PbZrO3, that is, Y exceeds 0.20 or less or 0.97, the piezoelectricity deteriorates significantly, so the above range was set.

If the molar fraction of PbTiOa, Z, is greater than the above value, it will be difficult to perform complete firing and the polarization process will not be completed, making it impossible to obtain a practical piezoelectric porcelain. It was set to 79 or less.

In addition, Cod, Nip, Fe2O* and SnO2 are
At least one element is added to improve piezoelectricity, but
If the total amount added is less than 0.05% by weight, little effect will be obtained, and if it exceeds 0.9% by weight, it will be extremely difficult to fire completely, and the resulting porcelain will not be practical. The above range was set because it did not exhibit the desired piezoelectricity.

(Example 1) Pb0 (or Pb5O4), Zr○, as raw materials
Using T i O, MnCO3 and 5bto3, these were weighed so that the product had the composition shown in Table 1,
After mixing in a wet mill for about 20 hours and drying, about 80
Calcined powder was obtained by calcining at 0°C for 2 hours. After adding an appropriate amount of binder to this calcined powder and grinding for 5 to 10 hours,
Granulate through an 80 mesh sieve, and pass through a sieve of 75 mesh.
Diameter 30III at pressure from 0 to 1000 kg/cm'
11. Thickness 1. On+n+ disk and diameter 1011111
1. After molding into a disk with a thickness of 1.01 mm, it was fired at the temperature shown in Table 1 to obtain a porcelain disk.

Silver electrodes were baked on both sides of each small-diameter porcelain disk, and a DC voltage of 34 to 4.0 KV/mm was applied in insulating oil at an appropriate temperature to polarize the sample.The electromechanical coupling coefficient ( Kp), mechanical quality factor (Qm), dielectric constant (ε
r) and the temperature coefficient (TC) of the resonance frequency were measured.

The piezoelectric properties were measured using an IRE standard circuit, and the dielectric constant was measured using a capacitance bridge. These results are shown in Table 1 along with the degree of deformation due to firing. The * mark in the table indicates a composition outside the scope of the present invention. The amount of deformation of the ceramic was determined by placing a large-diameter disk on a surface plate as shown in FIG. 2 before and after firing, and measuring the distance between the surface plate and the contact piece.

(Margins below) As is clear from the results in Table 1, the piezoelectric porcelain composition according to the present invention has a deformation amount of about 10% less than that of the conventional composition due to firing.
By not only reducing the amount to 1/2, but also appropriately setting the composition within the above range, the Qm far exceeds the conventional 2000 and reaches nearly 4000, and the Kp
can be selected from any value in the range of 20-60%, and it is also possible to obtain a temperature coefficient of resonant frequency of 30 ppm/'C or less. Furthermore, a material with a large K t/K p, that is, a material with large piezoelectric anisotropy can also be obtained.

In particular, as is clear from the results for sample number 24.25.30, the piezoelectric ceramic composition of the present invention has significantly thicker Kp and Qmp (and also has very good temperature characteristics of resonance frequency). The amount of deformation due to firing is also extremely small.

Furthermore, from the results for sample numbers 36 to 44, even if the composition ratios of the three components were the same, the third component, Pb (Mn
αsb, -α)03 composition ratio, specifically, by setting α to a value within the above range, the temperature characteristics of the resonant frequency are improved, but outside the above range, the piezoelectricity and dielectricity are extremely poor. It turns out that it is low and not suitable for practical use.

Other samples within the scope of the present invention exhibit very good frequency stability and are suitable for use in filters and oscillators.

(Example 2) Along with the raw materials used in Example 1, Coo, NiO, Fe,
○ and Snow, piezoelectric porcelain samples made of the compositions shown in Table 2 were similarly obtained, and their electromechanical coupling coefficient (Kp), mechanical quality coefficient (Qm), and relative permittivity (εr ) was measured. The results are shown in Table 2.

(Margin below) Table 2 No. Main ingredient Additive Kp
Qmp εxyz α (weight%) (%)
45*0.06 0.44 0.50 0.9/3
- 45.0 2410 130046/ノ”〃〃
CooO,0552,02490129047//
/l // l/ // Q, 10
54.0 2760 130048 //
// // /I N O, 1554,
72430145049〃〃” ” NiOO
,0553,62580132050//”
// // // // 0.1G 55.
0 2700 145051//IIノII//10.
1554.32450147052tt//ノ'”Fe
tusO,0553,22950128053〃〃//
# // 0.10 54.2 259
0 138054 〃// N //
” 0.15 54.0 2370 141055
” ” ” ” 5nOz0.
05 51.0 2890 129056 〃”
//〃〃0.10 5G, 5 2400
132057 〃N 〃〃NO,1550
,52380135058” // //
” IO, 3056, 42200145059
// // 〃” 〃0.60 58.5
2100 141060 N N 〃〃”
0.90 59.3 1910 1360 As is clear from the results in Table 2, Cod, NiO, Fe, 03
Or by adding SnO, Kp and Q
+++ both improve, Kp is 50% or more and Qm is 200
0 or more can be obtained.

(Effects of the Invention) As is clear from the above description, according to the present invention, piezoelectric porcelain that undergoes significantly less deformation during firing and has good electrical and temperature characteristics can be obtained, and a large amount of power can be input. Piezoelectric porcelain with high Qm, whose piezoelectricity does not easily deteriorate even when
It is possible to obtain a material with arbitrary characteristics depending on the application, such as a material with a high Kp, a material with excellent temperature characteristics of resonance frequency, or a material with large piezoelectric anisotropy.

In particular, by appropriately selecting its composition, it has a high Qm and a high electromechanical coupling coefficient suitable for powerful ultrasonic vibrators such as ultrasonic cleaners, ultrasonic humidifiers, and ultrasonic motors, and can be used under large amplitude conditions. ceramic elements with extremely low heat generation, ceramic elements with high Qm and good temperature characteristics suitable for filters and oscillators, and ceramic elements with large piezoelectric anisotropy suitable for ultrasonic probes, underwater sonar, etc. Excellent effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the change in surface temperature of a four-component ceramic composition due to applied voltage, and FIG. 2 is a diagram showing a method for measuring the amount of deformation of the porcelain. 1 - surface plate, 2... ceramic element, 3 - contact piece.

Claims (2)

[Claims] (1) General formula: X・Pb(MnαSb_1_-α)O_3-Y・PbZ
rO_3-Z・PbTiO_3 (where X, Y, Z and α are the mole fractions of each component, respectively, X+Y+Z=1
．． 00) Satisfies 0.4/3≦α≦1.5/3. However, α=1/3 is excluded. ) and whose vertices are points A, B, C, D, and E of the following composition in Figure 1.
A piezoelectric ceramic composition comprising a ternary solid solution having a composition within the range defined by DE. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (2) The piezoelectric ceramic composition according to claim 1, which contains 0.05 to 0.9% by weight of at least one selected from the group consisting of CoO, NiO, Fe_2O_3, and SnO_2 as an additive.