JPH06305830A - Piezoelectric material and ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric composition having excellent breaking toughness and electromechanical coupling coefficient k3,3' by specifying the composition of a ceramic composition of the formula Pb(Sc1/2Nb12)O3-PbTiO3-PbZrO3-Pb(Me1/3Nb2/3)O3 (Me is Mg, Zr or Ni). CONSTITUTION:This piezoelectric composition is expressed by the formula xPb(Sc1/2Nb1/2)O3-yPbTiO3-zPbZrO3-wPb(Me1/3Nb2/3)O3 (x+y+z+w=1.00). When the composition is described as a point in a regular trigonal pyramid coordinate having the Pb(Sc1/2Nb1/2)O3, PbTiO3, PbZrO3 and Pb(Me1/3Nb2/3)O3 as four apices P1 to P4, the values (x), (y), (z) and (w) are defined get a composition falling in the region formed by connecting the points a (x=0.72, y=0.28, z=0.00, w=0.00), b (x=0.02, y=0.98, z=0.00, w=0.00), c (x=0.02, y=O.28, z=0.70, w=0.00) and d (x=0.02, y=0.20, z=0.00, w=0.78) with straight lines (excluding the composition falling on the line ab).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric material and an ultrasonic probe useful for a medical diagnostic apparatus, etc., which is provided with a piezoelectric body made of the piezoelectric material.

[0002]

2. Description of the Related Art An ultrasonic probe has an ultrasonic transmitting / receiving element having a piezoelectric element. The ultrasonic probe is
It is used to image the internal state of the object by irradiating the object with ultrasonic waves and receiving reflected echoes from interfaces of the object having different acoustic impedances. An ultrasonic imaging apparatus incorporating such an ultrasonic probe is applied to, for example, a medical diagnostic apparatus for inspecting the inside of a human body and an inspection apparatus for detecting flaws inside a metal weld.

In recent years, as one of the medical diagnostic devices,
In addition to the tomographic image of the human body (B-mode image), the blood velocity can be displayed in two dimensions in color using the Doppler shift due to the blood flow of ultrasonic waves for the heart, liver, carotid artery, etc. A device employing the "flow mapping (CFM) method" has been developed, and the diagnostic capability of the medical diagnostic device has been dramatically improved. The medical diagnostic device adopting the CFM method is used for all organs of the human body such as the uterus, liver, and spleen store,
It is used for the diagnosis of organs, and in the future, research is being conducted aiming at a device capable of diagnosing coronary thrombosis.

In the case of the former B-mode image, it is required that a high-resolution image can be obtained with high sensitivity so that a small lesion or void due to a physical change can be clearly seen deep. In the case of the Doppler mode capable of obtaining the latter CFM image, since the reflection echo from a minute blood cell having a diameter of about several μm is used, the signal level obtained becomes smaller than that in the case of the B mode, and Higher sensitivity is required.

By the way, conventionally, the ultrasonic transmitting / receiving element constituting the ultrasonic probe has the following structure in view of its performance. (1) The attenuation of ultrasonic waves when ultrasonic waves are applied to a living body by an ultrasonic probe is 0.5 to 1 dB / MHz except for bones.
Since it is about cm, it is preferable to lower the frequency of the ultrasonic wave emitted from the ultrasonic transmitting / receiving element in order to obtain a highly sensitive signal from the living body. However, if the frequency is lowered too much, the wavelength of the ultrasonic wave may become long and the resolution may be deteriorated. Therefore, the ultrasonic wave having a frequency of 2 to 10 MHz is normally emitted.

(2) The piezoelectric body of the ultrasonic transmission / reception element may be formed of a material having a large electromechanical coupling coefficient and a large permittivity that is easy to match with a transmission / reception circuit with little loss due to cables or device stray capacitances. is necessary.
Therefore, the piezoelectric body is mainly formed of lead zirconate titanate (PZT) ceramic.

(3) An array type ultrasonic probe in which several tens to 200 ultrasonic transmitting / receiving elements having strip-shaped piezoelectric bodies are arranged has a high resolution. However, the above-mentioned conventional ultrasonic probe has the following problems.

That is, in the array type ultrasonic probe, there is a tendency that the number of piezoelectric bodies used increases as the resolution increases. When such an ultrasonic probe is brought into contact with a living body, it is necessary to reduce the width of the piezoelectric body because the diameter of the ultrasonic wave emitting surface cannot be increased. Width 10 from block-shaped PZT ceramic
A dicer used for cutting a semiconductor silicon wafer or the like is used to process a strip-shaped piezoelectric body of 0 micron or less. However, since a piezoelectric body is likely to be cracked during processing by the dicer, a piezoelectric material having more excellent fracture toughness is required.

In addition, in the above-mentioned ultrasonic probe, when the number of piezoelectric bodies increases, the impedance per piezoelectric body becomes high, and it becomes difficult to obtain impedance matching with the drive circuit. Become. It is possible to avoid such matching by using PZT having a large dielectric constant. However, since the PZT-based ceramic has a property that the electromechanical coupling coefficient becomes small when the relative dielectric constant exceeds 3000, a new problem arises that the sensitivity is lowered.

As described above, in the ultrasonic probe using PZT as the piezoelectric body, the width of the piezoelectric body is set to 100 in the manufacturing process.
If it is narrowed down to about μm or less, cracking tends to occur. Also,
The narrow rectangular piezoelectric body tends to have a reduced electromechanical coupling coefficient k ₃₃ ′ in the thickness direction.

On the other hand, V. J. Tennery et al.
AM. CERAM. SOC, VOL. 51, NO. 1
2, pp 671-673 (1968), said PZ
Pb (Sc _1/2 Nb _1/2 ) 0 as a piezoelectric material replacing T
It has reported a ₃ -PbTiO _3-based ceramic composition. However, the porcelain composition has a firing temperature of 1320 to 138.
Since the temperature is extremely high at 5 ° C, there is much evaporation of lead oxide during firing,
The sintering density is as low as 93% or less of the theoretical density. Therefore, the porcelain composition is not sufficiently satisfactory in terms of fracture toughness. As a result, when a piezoelectric body having a width of 100 μm or less is cut out from the block of the porcelain composition for application to an ultrasonic probe, there is a problem that cracks occur. In addition, the electromechanical coupling coefficient k _{p of the} piezoelectric body is as small as about 46% at maximum, which is a value less attractive than that of PZT (k _p ; 60% or more). It could not be put to practical use as a material.

[0012]

An object of the present invention is to provide a piezoelectric composition having excellent fracture toughness and a large electromechanical coupling coefficient (k ₃₃ ′). Another object of the present invention is to provide an ultrasonic probe which has a piezoelectric body having a narrow width and a large electromechanical coupling coefficient (k ₃₃ ′), which can be easily matched with a transmission / reception circuit, and which can further improve sensitivity. Is what you are trying to do.

[0013]

The piezoelectric material according to the present invention has the formula xPb (Sc _1/2 Nb _1/2 ) 0 _3-.
yPbTiO ₃ -zPbZrO ₃ -wPb (Me _1/3 N
b _2/3 ) O ₃ (wherein Me is at least one metal selected from the group consisting of Mg, Zn and Ni, x + y + z + w =
1.00)), and x, y, z and w are defined as the values (excluding on the line segment ab) of the regions where the points a, b, c and d below are linearly connected, respectively. Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ , P containing the composition
An equilateral triangular pyramid having bZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ is drawn, and the vertices P ₁ , P ₂ , P ₃ and P ₄ are drawn. The coordinates of (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0, 0,
0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0, 0),
(X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0), (X
₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points a, b, c, d are located on the surface of the regular triangular pyramid, and the coordinates X, Y, It is characterized by being represented by Z and W.

X Y Z W a 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 An ultrasonic probe according to the present invention is formed on a piezoelectric body having an ultrasonic wave transmitting / receiving surface, an ultrasonic wave transmitting / receiving surface of the piezoelectric body, and a surface opposite to the transmitting / receiving surface. And a pair of electrodes, wherein the piezoelectric body has the formula xPb (Sc _1/2 Nb
_1/2 ) 0 ₃ -yPbTiO ₃ -zPbZrO ₃ -wPb
(Me _1/3 Nb _2/3 ) O ₃ (However, Me is Mg, Z
at least one metal selected from the group of n and Ni, x +
y + z + w = 1.00), and x, y, z and w are defined as values (excluding line segment ab) of a region in which points a, b, c and d below are linearly connected, respectively. Containing Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbT
iO ₃ , PbZrO ₃ and Pb (Me _1/3 Nb _2/3 )
An equilateral triangular pyramid having O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ is drawn, and the coordinates of the vertices P ₁ , P ₂ , P ₃ and P ₄ are (X ₁ , Y ₁ , Z ₁ , W ₁ =
1,0,0,0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0,
1,0,0), (X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0,
1,0), (X ₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0,
When described in 1), the points a, b, c, and d are located on the surface of the regular triangular pyramid, and are made of a piezoelectric material represented by coordinates X, Y, Z, and W.

X Y Z W a 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 Hereinafter, the piezoelectric material according to the present invention will be described in detail with reference to FIGS.

The piezoelectric material of the present invention has the formula xPb (Sc
_{1/2 Nb 1/2) 0 3 -yPbTiO 3} -zPbZrO 3
-WPb (Me _1/3 Nb _2/3 ) O ₃ (where Me is M
g, Zn, at least one metal selected from the group consisting of Ni and x + y + z + w = 1.00), wherein x, y, z and w are linear points at points a, b, c and d below. The composition is defined as the value of the area bounded by (except on line ab).

That is, as shown in FIG. 1, the regular triangular pyramid 1 has Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ , PbZ.
rO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ are drawn as vertices P ₁ , P ₂ , P ₃ and P ₄ , respectively, and the vertices P ₁ , P ₂ , P ₃ and The coordinates of P ₄ are (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0, 0,
0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0, 0),
(X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0), (X
₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1). For example, from the apex P ₁ to the P ₂ , P ₃ and P
_The regular triangular pyramid 1 vertically lowered on the plane of the regular triangle connecting ₄
The midpoint of the height of is the coordinate (X = 0.5, Y = 0.5 /
3, Z = 0.5 / 3, W = 0.5 / 3). Further, in the regular triangular pyramid 1, the surface of the regular triangle that is parallel to the surface of the regular triangle and crosses the midpoint of the height is coordinate (X =
0.5, Y + Z + W = 0.5).

The points a, b, c and d which define the area are located on the surface of the regular triangular pyramid 1 and of the vertices P ₁ , P ₂ , P ₃ and P ₄ of the regular triangular pyramid 1. Coordinates X, Y,
It is expressed as follows using Z and W.

X Y Z W a 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 In other words, x, y, z and w are a (X = 0.72, Y = 0.28, Z = 0.00, W = 0.00 on the surface of the regular triangular pyramid 1 shown in FIG. ),
b (X = 0.02, Y = 0.98, Z = 0.00, W = 0.00), c (X = 0.0
2, Y = 0.28, Z = 0.70, W = 0.00) and d (X = 0.02, Y =
0.20, Z = 0.00, W = 0.78) is defined as the value (excluding on the line segment ab) of the area drawn by the triangular pyramid 2 that linearly connects the points.

The piezoelectric material according to the present invention may be a sintered body or a single crystal. The reason for defining the values of x, y, z and w of the composition contained in the piezoelectric material according to the present invention will be described below.

When x, y, z and w are values outside the line segment ac in the region drawn by the triangular pyramid 2 in FIG. 1, the block made of the piezoelectric material containing the composition is 100 μm wide.
The electromechanical coupling coefficient k ₃₃ ′ in the thickness direction is reduced to 50% or less when processed into the following rectangular piezoelectric body. Further, the piezoelectric material containing the composition has a large amount of lead oxide vaporized during firing, and thus it is difficult to achieve a sufficient density.

When x, y, z, and w are values outside the line segment ad in the region drawn by the triangular pyramid 2 in FIG. 1, a block made of a piezoelectric material containing the above composition has a width of 100 μm.
The electromechanical coupling coefficient k ₃₃ ′ in the thickness direction is reduced to 50% or less when processed into the following rectangular piezoelectric body. Further, the piezoelectric material having the composition has a Curie temperature of 150 ° C. or lower, which indicates the upper limit temperature of use of the piezoelectric body.

When x, y, z, and w are values outside the line segment bc in the region drawn by the triangular pyramid 2 in FIG. 1, even if an oxide such as La ₂ O ₃ described later is added, excellent fracture is achieved. Toughness cannot be obtained. Further, when a piezoelectric material (for example, a sintered body) containing the composition is processed into a rectangular piezoelectric body having a width of 100 μm or less, the electromechanical coupling coefficient k ₃₃ ′ in the thickness direction decreases.

When x, y, z and w are values outside the line segment bd in the region drawn by the triangular pyramid 2 in FIG. 1, a low dielectric constant pyrochlore phase is likely to occur in the composition.
Therefore, a piezoelectric material (for example, a piezoelectric material) containing a composition in which x, y, z, and w are values within a region drawn by a triangular pyramid 2 which linearly connects points a, b, c, and d in FIG. Union)
Has excellent fracture toughness, can suppress the occurrence of cracks during processing, and has a large electromechanical coupling coefficient (k ₃₃ ′).

The composition contained in the piezoelectric material according to the present invention has the values of x, y, z and w within the region drawn by the triangular pyramid 2 in FIG. 1, and Pb (Sc _1/2 Nb _{1 / 2} ) 0
₃ , PbTiO ₃ , zPbZrO ₃ and Pb (Me
It is preferred to include all _1/3 Nb _2/3 ) O ₃ .

The composition contained in the piezoelectric material according to the present invention has the above formula xPb (Sc _1/2 Nb _1/2 ) 0 ₃ -yPb.
TiO ₃ -zPbZrO ₃ -wPb (Me _1/3 Nb
_2/3 ) x, y, z, w of O ₃ are the following e, f, g, h, i
It is preferable to have a value (excluding on the line segment ef) of a region in which the points of and j are linearly connected. That is, as shown in FIG. 2, Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ ,
A regular triangular pyramid 1 having PbZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ is drawn, and the vertices P ₁ , P ₂ , P ₃ and P are drawn. _Four
The coordinates of (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0,
0,0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0,
0), (X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0),
When expressed by (X ₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points e, f, g, h, i and j are located on the surface of the regular triangular pyramid 1. And are represented by coordinates X, Y, Z and W.

X Y Z W e 0.65 0.35 0.00 0.00 f 0.55 0.45 0.00 0.00 g 0.02 0.40 0.58 0.00 h 0.02 0.50 0.48 0.00 i 0.02 0.28 0.00 0.70 j 0.02 0.38 0.00 0.60 In other words, x, y, z and w are shown in FIG. E on the surface of the regular triangular pyramid 1 (X = 0.65, Y = 0.35, Z = 0.00, W = 0.00),
f (X = 0.55, Y = 0.45, Z = 0.00, W = 0.00), g (X = 0.0
2, Y = 0.40, Z = 0.58, W = 0.00), h (X = 0.02, Y = 0.50,
Z = 0.48, W = 0.00), i (X = 0.02, Y = 0.28, Z = 0.00, W
= 0.70) and j (X = 0.02, Y = 0.38, Z = 0.00, W = 0.60
) Is defined as a value (excluding on the line segment ef) of a region drawn by the triangular prism 3 in which the points are linearly connected.

The value of a region (line segment ef) drawn by a triangular prism 3 which linearly connects the points e, f, g, h, i, and j shown in FIG. Piezoelectric materials containing the above mentioned compositions have a much higher electromechanical coupling coefficient (k ₃₃ ′).

The composition contained in the piezoelectric material according to the present invention has the above formula xPb (Sc _1/2 Nb _1/2 ) 0 ₃ -yPb.
TiO ₃ -zPbZrO ₃ -wPb (Me _1/3 Nb
_2/3 ) x, y, z, w of O ₃ are the following g, h, i, j,
It is more preferable to have the value of the area | region which connected the point of k, l, m, and n linearly. That is, as shown in FIG. 3, (Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ , Pb
An equilateral triangular pyramid 1 having bZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ , respectively, is drawn, and the vertices P ₁ , P ₂ , P ₃ and P are drawn. _{The four} coordinates are (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0,
0,0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0,
0), (X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0),
When expressed by (X ₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points g, h, i, j, k, l, m and n are the same as those of the regular triangular pyramid 1. It is located on the plane and is represented by the coordinates X, Y, Z and W.

X Y Z W g 0.02 0.40 0.58 0.00 h 0.02 0.50 0.48 0.00 i 0.02 0.28 0.00 0.70 j 0.02 0.38 0.00 0.60 k 0.64 0.35 0.01 0.00 l 0.54 0.45 0.01 0.00 m 0.64 0.35 0.00 0.01 n 0 .54 0.45 0.00 0.01 In other words, x, y, z, and w are g (X = 0.02, Y = 0.40, Z = 0.58, W on the surface of the regular triangular pyramid 1 shown in FIG. = 0.00),
h (X = 0.02, Y = 0.50, Z = 0.48, W = 0.00), i (X = 0.0
2, Y = 0.28, Z = 0.00, W = 0.70), j (X = 0.02, Y = 0.38,
Z = 0.00, W = 0.60), k (X = 0.64, Y = 0.35, Z = 0.01, W
= 0.00), l (X = 0.54, Y = 0.45, Z = 0.01, W = 0.00),
m (X = 0.64, Y = 0.35, Z = 0.00, W = 0.01) and n (X
= 0.54, Y = 0.45, Z = 0.00, W = 0.01) is defined as the value of the area drawn by the substantially triangular prism 4 which connects the points linearly. The region is present in a narrower range than the region in which the points e, f, g, h, i and j shown in FIG. 2 are linearly connected.

A piezoelectric material containing a composition in which x, y, z and w have values in the region drawn by the substantially triangular prism 4 shown in FIG. 3 has a much higher electromechanical coupling coefficient (k _33). ′) And the sintering temperature is further reduced, so that reproducibility can be improved. In addition, since the amount of scandium oxide, which is the most expensive in the composition, can be reduced, cost reduction can be realized. In addition, in the composition where x, y, z and w are values in the region drawn by the substantially triangular prism 4 in FIG. 3, x, y
The dielectric constant of the piezoelectric material including the composition of the composition of w and w is further improved, so that the impedance matching between the ultrasonic probe provided with the piezoelectric material of the piezoelectric material and the drive circuit can be facilitated. .

The above Pb (Sc _1/2 Nb _1/2 ) 0 ₃ -Pb
_{TiO 3 -PbZrO 3 -Pb (Me 1/3} Nb 2/3) O
_The composition of ₃ (however, Me is at least one selected from Mg, Zn and Ni) may be slightly deviated from the stoichiometric ratio. The Me may be not only one kind but also a combination of two or more kinds.

The piezoelectric material according to the present invention is represented by the above formula, and x, y, w, and w have values (including on the line segment ab) within the region drawn by the triangular pyramid 2 in FIG. In the composition, a part of Pb is allowed to be replaced with at least one element selected from the group of Ba, Sr and Ca. The piezoelectric material containing the composition obtained by substituting Pb with such a metal has a high dielectric constant. However, if the amount of substitution of the metal is too large, the Curie temperature tends to decrease, so the amount of substitution is 25 mol%.
The following is preferable. A more preferable substitution amount of the metal is 10 mol% or less.

The composition in which a part of Pb is replaced with the above-mentioned element has x, y, z and w having values in the region drawn by the triangular pyramid 2 in FIG. 1 and Pb (Sc _1/2 Nb
_1/2 ) 0 ₃ , PbTiO ₃ , zPbZrO ₃ and Pb
It is preferable to contain at least one component selected from (Me _1/3 Nb _2/3 ) O ₃ .

The piezoelectric material according to the present invention is represented by the above formula, and x, y, w, and w have values (including on the line segment ab) within the region drawn by the triangular pyramid 2 in FIG. composition 0.001 mol% of _{La 2 0 3, Nb 2 O} 5, Ta
It is allowed to further contain at least one oxide selected from the group of ₂ O ₅ , WO ₃ , MnO and CoO. By containing such an oxide, the fracture toughness of the piezoelectric material can be improved. Further, by processing the block made of the piezoelectric material into a rectangular shape, a piezoelectric body having a large electromechanical coupling coefficient k ₃₃ ′ in the thickness direction exceeding 50% can be obtained.

The content of the oxide is defined for the following reason. When the content of the oxide is 0.
If it is less than 001 mol%, it becomes difficult to improve the fracture toughness and the electromechanical coupling coefficient. On the other hand, when the content of the oxide exceeds 3 mol%, the firing temperature becomes high and it becomes difficult to obtain a piezoelectric body having a high density. Further, the electromechanical coupling coefficient is rather lowered. The more preferable content of the oxide is in the range of 0.1 to 2 mol%.

The composition to which the oxide is added is
x, y, z and w have values in the region depicted by the triangular pyramid 2 in FIG. 1, and Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ and zPbZrO ₃ and Pb (Me _{1 / 3} N
It preferably contains at least one component selected from b _2/3 ) O ₃ .

The piezoelectric material according to the present invention is permitted to contain additives, substitutes, impurities, etc. other than the above oxides within a range that does not impair the effects of the present invention. Specifically, Nd
Lanthanide elements such as ₂ O ₃ , Sm ₂ O ₃ , MoO ₆ , V
Additives such as ₂ O ₅ and Pb (B1, B2) O ₃ (where B
1 is Mg, Zn, Ni, Fe, B2 is Ta, W)
You may contain several mol% of composite perovskite compounds, such as. The additives may be in the form of other compounds such as Pb.
Nb ₂ O ₆ , PbTa ₂ O ₆ , Pb (Mn _1/3 Nb
_2/3 ) O ₃ or the like. By using such an additive, the firing temperature of the piezoelectric material can be lowered. In addition, Bi ₂ O ₃ , K ₂ O, Sb ₂
Impurities such as O ₃ , Cr ₂ O ₃ and HfO ₂ are 0.1 mol%
The following may be contained.

Next, a method of manufacturing the piezoelectric material of the present invention will be described. First, oxides of Sc, Nb or carbonates, oxalates, hydroxides, organic compounds, etc. which become oxides upon firing are weighed in approximately equimolar amounts, sufficiently mixed and pulverized to form 1100-110.
Calcination at 1300 ° C. Subsequently, the obtained calcined product was crushed, and the calcined powder and Pb, Ti, Zr, Mg, Ni,
Zn, La, Nb, Ta, W, Ba, Sr, Ca, M
An oxide of n, Co or the like, or a predetermined amount of a carbonate, an oxalate, a hydroxide, an organic compound or the like which becomes an oxide upon firing is sufficiently mixed and pulverized, and then calcined at 700 to 900 ° C. At this time, PbNb ₂ O ₆ , PbTa ₂ O ₆ , Pb (Mn
An oxide such as _1/3 Nb _2/3 ) O ₃ may be mixed. By adding such an oxide, it becomes possible to perform the firing step described later at a low temperature.

The production of the calcined product is performed by using Sc, Nb, Pb,
Ti, Zr, Mg, Zn, Ni, La, Ta, W, B
a, Sr, Ca, Mn, Co and other oxides, or carbonates, oxalates, hydroxides, organic compounds, etc., which are converted into oxides by firing, are mixed in a predetermined amount at a time, pulverized, and then calcined. Good.

Then, the obtained calcined product is pulverized, mixed with an appropriate binder and solvent, granulated, molded into a predetermined shape to remove the binder, and then fired to obtain the piezoelectric material (sintered) of the present invention. Body) is manufactured.

In the above method, the temperature is 1200 to 13
A dense fired body having a theoretical density of 95% or more can be obtained under the firing conditions of 00 ° C. Furthermore, the density of the sintered body obtained by adopting hot pressing or HIP is improved. Such a sintered body is processed into a desired shape, an electrode is formed on the obtained piezoelectric body, and the piezoelectric body is formed at a temperature of 20 to 200 ° C. for 1 to 3 times.
A piezoelectric vibrator can be manufactured by applying an electric field of kV / mm to perform polarization.

In the above-mentioned method for manufacturing a piezoelectric material,
Although the usual solid phase method was adopted, a chemical synthesis method such as a sol-gel method, a coprecipitation method, a hydrothermal synthesis method, an alkoxide method or a sputtering apparatus, and a thin film method using a CVD apparatus was used for the preparation of the powder. May be.

A method for producing the single crystallized piezoelectric material according to the present invention will be described below. First, a calcined powder is produced by the same method as the above-mentioned porcelain (sintered body). Next, lead oxide (Pb
O) and boron oxide (B ₂ O ₃ ) are mixed in a desired ratio and then filled in a platinum crucible. Subsequently, the mixture in the platinum crucible is heated to 1000 to 1300 ° C., held for several hours, and then cooled to 850 ° C. at 1 to 10 ° C./hour. Then, the molten mixture in the crucible is cooled to room temperature and boiled with an aqueous nitric acid solution to take out a single crystal (piezoelectric material).

In the case of the above-mentioned sintered body, the single crystal obtained by such a method is processed into a desired shape with the orientation determined by using a Laue X-ray device, and electrodes are formed on the obtained piezoelectric body. Polarize in the same manner as above to produce a vibrator.

As the method for producing the single crystal, other than the flux method, the Kyroplas method, the Czochralski method, the Bridgman method, the hydrothermal growth method, the thin film method and the like can be adopted.
Hereinafter, the ultrasonic probe according to the present invention will be described in detail with reference to FIG.

A plurality of piezoelectric bodies 11 made of a piezoelectric material are separated from each other and adhered to the backing material 12. Each of the piezoelectric bodies 11 vibrates in the direction of arrow A in the figure. First
The electrodes 13 are formed from the ultrasonic wave transmitting / receiving surface of each piezoelectric body 11 to the side surface thereof and a part of the surface opposite to the transmitting / receiving surface. The second electrode 14 is
The piezoelectric body 11 is formed on a surface of the piezoelectric body 11 opposite to the transmitting / receiving surface with a desired distance from the first electrode 13. The piezoelectric body 11 and the first and second electrodes 13 and 14 as described above constitute an ultrasonic transmitting / receiving element. The acoustic matching layer 15 is formed on the ultrasonic wave transmitting / receiving surface of each piezoelectric body 1 including each of the first electrodes 3. The acoustic lens 16 is formed over the entire acoustic matching layer 15. The flexible printed wiring board 18 is connected to each of the first electrodes 13. The ground electrode plate 17 is connected to each of the second electrodes 4 by, for example, soldering. A plurality of conductors (cables) not shown are connected to the flexible printed wiring board 18 and the ground electrode board 17, respectively.

The ultrasonic probe having the structure shown in FIG. 4 is manufactured by the following method, for example. First,
A conductive film is vapor-deposited on a piezoelectric material, for example, a flat plate-shaped sintered body by a sputtering method, and a conductive film is left on the ultrasonic wave transmitting / receiving surface and the surface opposite to the transmitting / receiving surface by a selective etching technique. Subsequently, an acoustic matching layer is formed on the surface of the single crystal piece that serves as the ultrasonic wave transmitting / receiving surface, and these are bonded onto the backing material 12. Continuing, first and second electrodes 13 are formed on the backing material 12 by cutting a plurality of times from the acoustic matching layer to the single crystal piece using a blade.
A plurality of piezoelectric bodies 11 having 14 are separated from each other, and a plurality of acoustic matching layers 15 arranged on the respective piezoelectric bodies 11 are formed. Next, after forming the acoustic lens 16 on the acoustic matching layer 15, the flexible printed wiring board 18 is connected to the first electrode 3 respectively, and the ground electrode plate 17 is connected to the second electrode 14 by, for example, soldering, Furthermore, multiple conductors (cables) not shown
Is connected to the flexible printed wiring board 18 and the ground electrode board 17 to produce an ultrasonic probe.

The piezoelectric body 11 has the formula xPb (Sc _{1/2
Nb 1/2) 0 3 -yPbTiO 3 -zPbZrO} 3 -w
Pb (Me _1/3 Nb _2/3 ) O ₃ (where Me is Mg,
At least one metal selected from the group of Zn and Ni, x
+ Y + z + w = 1.00), and x,
y, z, and w are defined as the values (excluding on the line segment ab) of the area drawn by the above-mentioned triangular pyramid 2 shown in FIG. 1 in which the points a, b, c, and d below are linearly connected. It consists of a piezoelectric material containing a composition. That is, as shown in FIG. 1 described above, Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ ,
A regular triangular pyramid 1 having PbZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ is drawn, and the vertices P ₁ , P ₂ , P ₃ and P are drawn. _Four
The coordinates of (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0,
0,0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0,
0), (X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0),
When expressed by (X ₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points a, b, c and d are located on the surface of the regular triangular pyramid 1 and have coordinates X. , Y, Z and W.

X Y Z W a 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 The composition contained in the piezoelectric material according to the present invention is x, y,
z and w have values within the region depicted by the triangular pyramid 2 in FIG. 1, and Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTi
O ₃ , zPbZrO ₃ and Pb (Me _1/3 Nb _2/3 )
It is preferable to include all O ₃ .

The piezoelectric body 11 is represented by the above formula, and x,
y, z and w are e (X = 0.65, Y = 0.35, z = 0.00, W = 0.00) on the surface of the regular triangular pyramid 1 shown in FIG. 2, respectively,
f (X = 0.55, Y = 0.45, Z = 0.00, W = 0.00), g (X = 0.0
2, Y = 0.40, Z = 0.58, W = 0.00), h (X = 0.02, Y = 0.50,
Z = 0.48, W = 0.00), i (X = 0.02, Y = 0.28, Z = 0.00, W
= 0.70) and j (X = 0.02, Y = 0.38, Z = 0.00, W = 0.60
More preferably, it is formed of a piezoelectric material containing a composition defined as a value (excluding a line segment ef) within a region drawn by a triangular prism 3 in which points (3) are linearly connected.

The piezoelectric body 11 is represented by the above formula, and x,
y, z, and w are g (X = 0.02, Y = 0.40, Z = 0.58, W = 0.00) and h on the surface of the regular triangular pyramid 1 shown in FIG. 3, respectively.
(X = 0.02, Y = 0.50, Z = 0.48, W = 0.00), i (X = 0.02,
Y = 0.28, Z = 0.00, W = 0.70), j (X = 0.02, Y = 0.38, Z
= 0.00, W = 0.60), k (X = 0.64, Y = 0.35, Z = 0.01, W =
0.00), l (X = 0.54, Y = 0.45, Z = 0.01, W = 0.00),
m (X = 0.64, Y = 0.35, Z = 0.00, W = 0.01) and n (X
= 0.54, Y = 0.45, z = 0.00, w = 0.01) is further formed from a piezoelectric material containing a composition defined as a value within a region drawn by a substantially triangular prism 4 in which points are linearly connected. preferable.

In the piezoelectric body 11, part of Pb in the above formula is replaced with at least one element selected from the group consisting of Ba, Sr, and Ca, and x, y, w, and w thereof are as described above. Allowed to be formed from a piezoelectric material that includes a composition having a value. The substitution amount of the element is preferably 25 mol% or less for the same reason as described for the piezoelectric material.

The composition in which a part of Pb is replaced by the element has x, y, z and w having the values within the region depicted by the triangular pyramid 2 in FIG. 1, and Pb (Sc _1/2 Nb
_1/2 ) 0 ₃ , PbTiO ₃ , zPbZrO ₃ and Pb
It is preferable to contain at least one component selected from (Me _1/3 Nb _2/3 ) O ₃ .

The piezoelectric body 11 is composed of the composition (provided that
(Including line segment ab in FIG. 1) 0.001 to 3 mol% L
_{a 2 0 3, Nb 2 O} 5, Ta 2 O 5, WO 3, allows at least one oxide is formed from a further piezoelectric material contained selected from the group consisting of MnO and CoO. The content of the oxide is defined for the same reason as described for the piezoelectric material.

The composition to which the oxide is added is
x, y, z and w have values in the region depicted by the triangular pyramid 2 in FIG. 1, and Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ and zPbZrO ₃ and Pb (Me _{1 / 3} N
It preferably contains at least one component selected from b _2/3 ) O ₃ .

The width of the piezoelectric body 11 is preferably 100 μm or less. The first and second electrodes 13, 14
Is formed of, for example, a bilayer metal film of Ti / Au, Ni / Au or Cr / Au.

According to the ultrasonic probe of the present invention,
Formula _{xPb (Sc 1/2 Nb 1/2) 0} 3 -yPbTiO 3
_{-ZPbZrO 3 -wPb (Me 1/3 Nb 2/3} ) O 3
(However, Me represents at least one kind of metal selected from the group of Mg, Zn, and Ni, x + y + z + w = 1.00), and each of x, y, z, and w is represented by the above-mentioned positive and negative values shown in FIG. The value of the area drawn by the triangular pyramid 2 that linearly connects the points a, b, c, and d on the surface of the pyramid 1 (the line segment a
a piezoelectric body made of a piezoelectric material containing a composition defined as (excluding b)). The piezoelectric material having such a composition is excellent in fracture toughness and has a large electromechanical coupling coefficient (k ₃₃ ′). Therefore, since the ultrasonic probe provided with the piezoelectric body made of the piezoelectric material can prevent the generation of cracks even during long-term use, it is possible to achieve a long life.

Further, it is possible to suppress the occurrence of cracks when the piezoelectric material (for example, a sintered body) is cut into strips by a dicer, and it is possible to form a piezoelectric body having a fine width of 100 μm or less. Therefore, even if a plurality of the piezoelectric bodies are arranged in an array and incorporated, an ultrasonic probe having a small ultrasonic emission surface can be realized. Such an ultrasonic probe can radiate ultrasonic waves to a minute portion of a living body and can diagnose that portion of the living body with high resolution.

Further, since the piezoelectric body has excellent toughness, a high voltage can be applied to the piezoelectric body without causing cracks or the like. As a result, it is possible to realize an ultrasonic probe that emits an ultrasonic wave having an extremely strong impact due to the interaction with the large electromechanical coupling coefficient (k ₃₃ ′) of the piezoelectric body. Such an ultrasonic probe can be effectively used for calculus breaking equipment.

[0061]

The preferred embodiments of the present invention will be described in detail below. Examples 1 to 47 First, a diameter of 5
Using a zirconia ball of mm and pure water, the purity is 99.
Equimolar crushed more than 9% of the Sc ₂ 0 ₃ and Nb ₂ O _5, were mixed, dried, and 4 hours and calcined at further 1200 ° C.. The obtained calcined product was ground again in the pot to prepare submicron ScNbO ₄ powder.

Similarly, MgO, Z having a purity of 99.9% or more
nO, NiO and Nb ₂ O ₅ are weighed equimolar and 0.7
The mixture was placed in a liter polyethylene pot, pulverized with zirconia balls having a diameter of 5 mm and pure water, mixed, dried, and calcined at 1150 ° C. for 4 hours. The obtained calcined product was pulverized again in the pot to obtain submicron MgNb.
Powders of ₂ O ₆ , NiNb ₂ O ₆ and ZnNb ₂ O ₆ were prepared.

Then, the ScNbO ₄ powder and MgNb are added.
₂ O ₆ , NiNb ₂ O ₆ and ZnNb ₂ O ₆ powder and PbO, TiO ₂ , ZrO ₂ having a purity of 99.5% or more,
BaCO ₃ , SrCO ₃ , CaCO ₃ and the additives shown in Table 1, Table 3, Table 5, Table 7 and Table 9 below have the compositions shown in Table 1, Table 3, Table 5, Table 7 and Table 9, respectively. Were weighed in this manner, pulverized in a pot mill using zirconia balls having a diameter of 5 mm and pure water, mixed, and dried to 800
It was calcined at ℃ for 2 hours. Subsequently, each of the obtained calcined products was ground again in a pot to prepare a submicron powder.
7% by weight of an aqueous polyvinyl alcohol solution having a concentration of 5% by weight was added to each of the powders and mixed in a mortar, and then granulated using a # 32 sieve.

Next, each of the granulated powders was molded into a shape having a diameter of 19 mm and a thickness of 2 mm at a pressure of 1 ton / cm ² , and 50
After debindering at 0 ° C., it was fired in the sheath of high-density magnesia under the conditions shown in Table 1, Table 3, Table 5, Table 7, and Table 9 below to obtain 47 kinds of piezoelectric materials, such as disc-shaped materials. A sintered body was manufactured.

The apparent specific gravity of each of the obtained disc-shaped fired bodies was measured. Further, the lattice constant of each of the sintered bodies was measured by an X-ray diffraction method. The apparent specific gravity of each sintered body was converted as the density ratio of the fired body from the ratio of the lattice constant to the theoretical density lattice constant. The density ratio of each sintered body was 95% or more of the theoretical density in each sintered body.

From each of the disc-shaped fired bodies, a diameter of 16
A disc sample having a thickness of 1 mm and a thickness of 1 mm and a square rod having a size of 1 mm and a thickness of 4 mm were prepared. A silver electrode was baked on the facing surface of these samples at 700 ° C.
While applying an electric field of 20 ° C. × 25 kV / mm, cooling to 25 ° C. and polarization were performed, and after 24 hours at room temperature,
For these samples, the dielectric constant, the electromechanical coupling coefficient kp in the circumferential spreading direction and the electromechanical coupling coefficient k _{33 in the} thickness direction.
Was measured respectively. Further, each of the disc-shaped fired bodies was processed into a shape having a diameter of 16 mm and a thickness of 400 μm, silver electrodes were baked on both sides thereof, and after polarization was performed in the same manner, a dicing saw having a diamond cutter with a thickness of 20 μm was used. Using a rectangular sample having a width of 200 μm, a thickness of 400 μm and a length of 10 mm and a width of 100 μm, a thickness of 4
A rectangular sample having a length of 00 μm and a length of 10 mm was cut out and the electromechanical coupling coefficient k ₃₃ ′ in the thickness direction was measured.
The electromechanical coupling coefficients kp, k ₃₃ and k ₃₃ ′ were obtained from the equations shown below using the resonance-antiresonance method. The results are shown in Table 2, Table 4, Table 6, Table 8 and Table 10 below.

[0067]

[Equation 1]

Further, the array type ultrasonic probe shown in FIG. 4 was manufactured by using each of the disc-shaped sintered bodies.
That is, the disk-shaped sintered body is processed to have a width of 10 mm,
A square plate having a length of 10 mm and a thickness of 400 μm was produced. A Ti / Au conductor film was vapor-deposited on the upper and lower surfaces and side surfaces of the obtained square plate by a sputtering method, and the conductive film portion located on one side surface of the square plate and a surface to be an ultrasonic wave transmitting / receiving surface were formed by a selective etching technique. A part of the conductive film located on the opposite surface was removed. Subsequently, after forming an acoustic matching layer on the surface of the square plate that serves as the ultrasonic wave transmitting / receiving surface, the flexible printed wiring board 18 was connected to the conductive film portion serving as the first electrode by soldering. In addition, the earth electrode 17
These were connected to the conductive film portion provided for the electrodes by soldering, and these were adhered onto the backing material 12. The flexible printed wiring board 18 and the ground electrode 17 may be connected to the conductor film using a conductive paste. Subsequently, a diamond blade was used to cut from the acoustic matching layer to the square plate, and cut into strips with a width of 100 μm. By this cutting, the backing material 12 having the first and second electrodes 13 and 14 separated from each other by a width of 100 μm, a length of 10 mm and a thickness of 400 μm 1
00 piezoelectric bodies 1 and a plurality of acoustic matching layers 15 arranged on the respective piezoelectric bodies 1 were formed. Next, after forming the acoustic lens 16 on the acoustic matching layer 15, the flexible printed wiring board 18 is formed on each of the first and second acoustic matching layers 15.
The electrodes 3 are connected to each other by soldering, the ground electrode plate 17 is connected to each of the second electrodes 14 by soldering, and a plurality of conductors (cables) (not shown) having 110 pF / m and a length of 2 m are connected to the flexible printed wiring board 18. An array type ultrasonic probe was manufactured by connecting it to the ground electrode plate 17 and the ground electrode plate 17, respectively.

For each of the obtained array-type ultrasonic probes, a voltage was applied to the piezoelectric body between the first and second electrodes of the array-type ultrasonic probe to measure the capacitance, and the capacitance of the vibrator without breakage of the piezoelectric body was used as a reference. Then, the number of 100 vibrators in which the capacity was reduced was determined. The results are shown in Table 2, Table 4, Table 6, Table 8 and Table 10 below.
Shown in. However, the capacitance measurement was performed on a probe to which the cable was not connected.

With respect to each piezoelectric body taken out by disassembling each ultrasonic probe after the capacitance measurement, the upper surface and the side surface thereof were observed with a microscope to check the number of cracks in 100 piezoelectric bodies. The results are shown in Table 2, Table 4, Table 6, Table 8 and Table 10 below.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

[0074]

[Table 4]

[0075]

[Table 5]

[0076]

[Table 6]

[0077]

[Table 7]

[0078]

[Table 8]

[0079]

[Table 9]

[0080]

[Table 10]

Examples 48 to 50 First, ScNbO ₄ powder and MgNb ₂ O ₆ and ZnNb ₂ O ₆ powders were produced by the same method as in Example 1. Continued. These powders, PbO and TiO ₂ having a purity of 99.9% or more, and the additives shown in Table 11 below were weighed so that the compositions shown in Table 11 were obtained, and zirconia balls having a diameter of 5 mm were placed in a pot mill. After crushing and mixing with pure water, it was dried and calcined at 800 ° C. for 2 hours. Each of the obtained calcined products was pulverized again in a pot to produce submicron powder.

Next, each of the calcined powders and lead oxide were mixed with each other at a ratio of 1:
Mix at a ratio of 3 and 200 ml of 1 kg of these mixtures
Each was placed in a platinum crucible of and sealed with a platinum lid.
Subsequently, each of the crucibles was set in an electric furnace and heated to 1250 ° C. at 100 ° C./hour. After holding for 6 hours, oxygen was introduced into the lower portion of each crucible, and the oxygen flow rate was adjusted so that the bottom portion was lower than the upper surface by 20 ° C. or more. Subsequently, it was cooled to 850 ° C at 1 ° C / hour. After that, cool to room temperature and add 24% with 20% nitric acid aqueous solution.
After boiling for 3 hours, three types of single crystals, which are piezoelectric materials, were taken out. Each single crystal obtained was in the shape of a square plate having a 10 mm square.

The orientation of each of the above single crystals is set to [100],
These were processed and the square plate sample of 8 mm x 8 mm x 0.4 mm was produced, respectively. A silver electrode was baked at 700 ° C on the facing surface of these samples, and 120 ° C in silicone oil.
The sample was cooled to 25 ° C. while applying an electric field of × 15 kV / mm for polarization, and after 24 hours at room temperature, the dielectric constants of these samples were measured. Further, a rectangular sample having a width of 200 μm, a thickness of 400 μm and a length of 6 mm and a rectangular sample having a width of 100 μm, a thickness of 400 μm and a length of 6 mm were prepared from each of the single crystals by using a dicing saw having a blade having a thickness of 20 μm. Were cut out, and the electromechanical coupling coefficient k ₃₃ ′ in the thickness direction was measured using the resonance-anti-resonance method similar to that in Example 1. The results are shown in Table 12 below.

Further, the array type ultrasonic probe shown in FIG. 4 described above was manufactured by the same method as in Example 1 using each of the above single crystals. In addition, the square plate is obtained by [10]
[0], the orientation was determined, and the one polished to a thickness of 400 μm was used. Further, using a dicing saw having a blade with a thickness of 20 μm, the acoustic matching layer was cut across the square plate to form 30 strip-shaped piezoelectric bodies having a width of 100 μm.

With respect to each of the obtained array type ultrasonic probes, a voltage was applied to the piezoelectric body between the first and second electrodes of the array type ultrasonic probe to measure the capacitance, and the capacitance of the vibrator without breakage of the piezoelectric body was used as a reference. Then, the number of 100 vibrators in which the capacity was reduced was determined. However, the capacitance measurement was performed on a probe to which the cable was not connected. As a result, the number of oscillators whose capacity was reduced was zero.

With respect to each piezoelectric body taken out by disassembling each ultrasonic probe after the capacitance measurement, the upper surface and the side surface thereof were observed with a microscope to check the number of cracks in 100 piezoelectric bodies. The results are shown in Table 2, Table 4, Table 6, Table 8 and Table 10 below.

[0087]

[Table 11]

[0088]

[Table 12]

Comparative Examples 1 to 11 ScNbO ₄ powder produced by the same method as in Example 1 and PbO, TiO ₂ and ZrO having a purity of 99.5% or more.
₂ , SrCO ₃ and the additives shown in 13 below were weighed so as to have the compositions shown in Table 13, pulverized in a pot mill with zirconia balls having a diameter of 5 mm and pure water, mixed, and then dried. It was calcined at 800 ° C. for 2 hours. Subsequently, each of the obtained calcined products was ground again in a pot to prepare a submicron powder. Pluck, 5 for each powder
7% by weight of a polyvinyl alcohol aqueous solution having a concentration of 5% by weight was added and mixed in a mortar, and then granulated using a # 32 sieve.

Next, each of the granulated powders was molded into a shape having a diameter of 19 mm and a thickness of 2 mm at a pressure of 1 ton / cm ² , and 50
After the binder was removed at 0 ° C., it was fired in a sheath of high-density magnesia under the conditions shown in Table 13 below to produce a disc-shaped sintered body that was 11 kinds of piezoelectric materials.

The apparent specific gravity of each of the obtained disc-shaped fired bodies was measured. Further, the lattice constant of each of the sintered bodies was measured by an X-ray diffraction method. The apparent specific gravity of each sintered body was converted as the density ratio of the fired body from the ratio of the lattice constant to the theoretical density lattice constant. The density ratio of firing is Comparative Examples 1 and 1.
All sintered bodies except 1 were 90% or more of the theoretical density.

Further, each of the disc-shaped fired bodies (Comparative Example 1,
(Except 11), a disc sample having a diameter of 16 mm and a thickness of 1 mm and a square rod sample having a 1 mm square and a length of 4 mm were prepared. A silver electrode was baked at 700 ° C. on the facing surface of each of these samples, and was cooled to 25 ° C. while applying an electric field of 120 ° C. × 25 kV / mm in silicone oil for polarization.
After 24 hours at room temperature, the dielectric constant, the electromechanical coupling coefficient kp in the circumferential direction and the electromechanical coupling coefficient k ₃₃ in the longitudinal direction of these samples were measured in the same resonance as in Example 1.
Each measurement was performed using the anti-resonance method. Further, each of the disc-shaped fired bodies (excluding Comparative Examples 1 and 11) was processed into a shape having a diameter of 16 mm and a thickness of 400 μm, and silver electrodes were baked on both sides thereof, and polarization was performed in the same manner. Two
Width of 2 using a dicing saw with a blade of 0 μm
00 μm, thickness 400 μm, length 10 mm rectangular sample and width 100 μm, thickness 400 μm, length 10 mm
Each of the rectangular samples was cut out, and the electromechanical coupling coefficient k ₃₃ ′ in the thickness direction was measured using the resonance-antiresonance method similar to that in Example 1. The results are shown in Table 14 below.

Further, the array type ultrasonic probe shown in FIG. 4 described above was manufactured by the same method as in Example 1 using each of the sintered bodies. With respect to each of the obtained array-type ultrasonic probes, a voltage is applied to the piezoelectric body between the first and second electrodes of the array-type ultrasonic probe to measure the capacitance, and the capacitance is reduced based on the capacitance of the oscillator without breakage of the piezoelectric body. The number of the 100 vibrators in which the occurrence of the above was found was determined. The results are shown in Table 14 below. However, the capacitance measurement was performed on a probe to which the cable was not connected.

With respect to each piezoelectric body taken out by disassembling each ultrasonic probe after the capacitance measurement, the upper surface and the side surface thereof were observed with a microscope to check the number of cracks in 100 piezoelectric bodies. The results are shown in Table 14 below.

[0095]

[Table 13]

[0096]

[Table 14]

As is clear from Tables 1 to 12, the formula xPb (Sc _1/2 Nb _1/2 ) 0 ₃ -yPbTiO _3-
zPbZrO ₃ -wPb (Me _1/3 Nb _2/3 ) O ₃ (wherein Me is at least one metal selected from the group of Mg, Zn, and Ni, x + y + z + w = 1.00), and x is , Y, z and w are a (x = 0.72, y
= 0.28, z = 0.00, w = 0.00), b (x = 0.02, y = 0.98, z =
0.00, w = 0.00), c (x = 0.02, y = 0.28, z = 0.70, w = 0.
00), d (x = 0.02, y = 0.20, z = 0.00, w = 0.78) containing a composition defined as a value within a region where points are linearly connected (except on the line segment ab) The sintered bodies (piezoelectric materials) of Examples 1 to 47 and the single crystals (piezoelectric materials) of Examples 48 to 50 have an electromechanical coupling coefficient k ₃₃ ′ in the thickness direction when processed into a rectangular shape having a width of 200 μm. 50% or more (8 for single crystal
It can be seen that the electromechanical coupling coefficient k ₃₃ ′ is hardly reduced even when the width is as large as 0% or more) and the width is narrowed to 100 μm.

The sintered bodies (piezoelectric materials) of Examples 1 to 47 and the single crystals (piezoelectric materials) of Examples 48 to 50 were
It has excellent fracture toughness with no cracking during the cutting process for incorporating it into the ultrasonic probe as a piezoelectric body. Therefore, the productivity can be improved, and the ultrasonic probe having a long life can be realized due to the excellent toughness of the piezoelectric body.

On the other hand, as shown in Tables 13 and 14, x, y, z, and w are a, b, and a shown in FIG.
Piezoelectric materials of Comparative Examples 1 to 11 having compositions deviating from the region drawn by the triangular pyramid 2 connecting the points of c and d have a width of 1
Electromechanical coupling coefficient k ₃₃ when processed into a rectangular shape of 00 μm
It can be seen that ′ is significantly reduced as compared with the case where it is processed into a rectangular shape having a width of 200 μm. Further, by comparing Table 2, Table 4, Table 6, Table 8, and Table 10 and Table 14, Comparative Examples 1 to 1 during the cutting step for incorporation into the ultrasonic probe.
It can be seen that the sintered body (piezoelectric material) of No. 1 is more easily cracked than in Examples 1 to 47.

[0100]

As described above, according to the present invention, it is possible to provide a piezoelectric material which is excellent in fracture toughness and has a large electromechanical coupling coefficient k ₃₃ ′ in the thickness direction when processed into a rectangular shape.

Further, since a piezoelectric body having a width of 100 μm or less and a large electromechanical coupling coefficient k ₃₃ ′ in the thickness direction can be formed without causing cracks or the like from the piezoelectric material, the piezoelectric body is provided with high resolution and high sensitivity. It is possible to realize a long-life ultrasonic probe.

[Brief description of drawings]

FIG. 1 is a quaternary diagram showing a composition range of a composition contained in a piezoelectric material according to the present invention.

FIG. 2 is a quaternary diagram showing a narrower composition range of the composition contained in the piezoelectric material according to the present invention.

FIG. 3 is a quaternary diagram showing a narrower composition range of the composition contained in the piezoelectric material according to the present invention.

FIG. 4 is a perspective view showing an ultrasonic probe according to the present invention.

[Explanation of symbols]

1 ... Regular pyramid, 2 ... Triangular pyramid, 3 ... Triangular prism, 4 ... Approximate triangular prism, 11 ... Piezoelectric material, 12 ... Backing material, 13,14 ...
Electrodes, 15 ... Acoustic matching layer, 16 ... Acoustic lens, 1
7 ... Ground electrode, 18 ... Flexible printed wiring board.

Claims (6)

[Claims] 1. The formula xPb (Sc _1/2 Nb _1/2 ) 0 ₃ −
yPbTiO ₃ -zPbZrO ₃ -wPb (Me _1/3 N
b _2/3 ) O ₃ (wherein Me is at least one metal selected from the group consisting of Mg, Zn and Ni, x + y + z + w =
1.00)), and x, y, z and w are defined as the values (excluding on the line segment ab) of the regions where the points a, b, c and d below are linearly connected, respectively. Containing the composition: Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ , PbZ
An equilateral triangular pyramid having rO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ , respectively, is drawn, and the vertices P ₁ , P ₂ , P ₃ and P ₄ are drawn. The coordinates of (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0, 0,
0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0, 0),
(X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0), (X
₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points a, b, c, d are located on the surface of the regular triangular pyramid, and the coordinates X, Y, A piezoelectric material characterized by being represented by Z and W. X Y Z Wa 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 2. 0.001 to ₃ mol% of La ₂ O ₃ , N
At least one oxide selected from the group consisting of b ₂ O ₅ , Ta ₂ O ₅ , WO ₃ , MnO and CoO is further added to the composition (including on the line ab). Item 1. The piezoelectric material according to item 1. 3. The composition to which the oxide is added comprises
x, y, z and w have values within the region,
Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ and zPb
The piezoelectric material according to claim 2, comprising at least one component selected from ZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ . 4. A piezoelectric body having an ultrasonic wave transmitting / receiving surface, and a pair of electrodes respectively formed on the ultrasonic wave transmitting / receiving surface of the piezoelectric body and a surface opposite to the transmitting / receiving surface, the piezoelectric body comprising: Formula xPb (Sc _1/2 Nb _1/2 ) 0 ₃ −
yPbTiO ₃ -zPbZrO ₃ -wPb (Me _1/3 N
b _2/3 ) O ₃ (wherein Me is at least one metal selected from the group consisting of Mg, Zn and Ni, x + y + z + w =
1.00)), and x, y, z and w are defined as the values (excluding on the line segment ab) of the regions where the points a, b, c and d below are linearly connected, respectively. Containing the composition: Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ , PbZ
An equilateral triangular pyramid having rO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ as vertices P ₁ , P ₂ , P ₃ and P ₄ , respectively, is drawn, and the vertices P ₁ , P ₂ , P ₃ and P ₄ are drawn. The coordinates of (X ₁ , Y ₁ , Z ₁ , W ₁ = 1, 0, 0,
0), (X ₂ , Y ₂ , Z ₂ , W ₂ = 0, 1, 0, 0),
(X ₃ , Y ₃ , Z ₃ , W ₃ = 0, 0, 1, 0), (X
₄ , Y ₄ , Z ₄ , W ₄ = 0, 0, 0, 1), the points a, b, c, d are located on the surface of the regular triangular pyramid, and the coordinates X, Y, An ultrasonic probe comprising a piezoelectric material represented by Z and W. X Y Z Wa 0.72 0.28 0.00 0.00 b 0.02 0.98 0.00 0.00 c 0.02 0.28 0.70 0.00 d 0.02 0.20 0.00 0.78 5. The piezoelectric material is the composition (line segment ab
La ₂ of 0.001 mol% to including on) 0 _3, Nb
_The ultrasonic probe according to claim 4, further comprising at least one oxide selected from the group consisting of ₂ O ₅ , Ta ₂ O ₅ , WO ₃ , MnO and CoO. 6. The composition to which the oxide is added comprises
x, y, z and w have values within the region,
Pb (Sc _1/2 Nb _1/2 ) 0 ₃ , PbTiO ₃ and zPb
The ultrasonic probe according to claim 5, which contains at least one component selected from ZrO ₃ and Pb (Me _1/3 Nb _2/3 ) O ₃ .