JP3075033B2 - Polarization method for piezoelectric ceramics - Google Patents
Polarization method for piezoelectric ceramicsInfo
- Publication number
- JP3075033B2 JP3075033B2 JP21752593A JP21752593A JP3075033B2 JP 3075033 B2 JP3075033 B2 JP 3075033B2 JP 21752593 A JP21752593 A JP 21752593A JP 21752593 A JP21752593 A JP 21752593A JP 3075033 B2 JP3075033 B2 JP 3075033B2
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- Japan
- Prior art keywords
- temperature
- polarization
- piezoelectric
- piezoelectric ceramic
- cooling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Compositions Of Oxide Ceramics (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、圧電セラミックスの分
極方法に関する。さらに詳しく述べるならば、本発明
は、圧電セラミックスを一旦分極させた後、急激に冷却
し、再び分極させる工程を含む圧電セラミックスの分極
方法に関するものであり、この方法により駆動耐久性の
高い圧電素子が得られる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polarizing piezoelectric ceramics. More specifically, the present invention relates to a method for polarizing a piezoelectric ceramic, which includes a step of once cooling a piezoelectric ceramic, rapidly cooling the same, and then repolarizing the piezoelectric ceramic. Is obtained.
【０００２】[0002]
【従来の技術】圧電体は強誘電体であり、その圧電性を
利用するためには分極しなければならない。分極処理を
行った圧電体は、時間と共にあるいは駆動後に分極量が
減少し、特性の低下を引起し、これはセンサー等に使用
する場合には大きな問題となる。2. Description of the Related Art Piezoelectric materials are ferroelectric materials and must be polarized in order to utilize their piezoelectricity. The amount of polarization of the piezoelectric body subjected to the polarization treatment decreases with time or after driving, causing deterioration in characteristics. This causes a serious problem when used in a sensor or the like.
【０００３】従来の一般的な分極処理方法は、80〜120
℃のシリコンオイル中で２〜５kV/mm の電界を加えて行
われる。ここで、温度が高い方が低い電界で分極するこ
とができる。しかし、温度が高すぎると抵抗率が低下し
て電流が流れ、絶縁破壊に至ってしまう。従って、分極
電解の大きさは温度との兼ね合いによってきまる。[0003] The conventional general polarization processing method is 80-120.
It is carried out by applying an electric field of 2 to 5 kV / mm in silicone oil at ℃. Here, the higher the temperature, the more the polarization can be performed with a lower electric field. However, if the temperature is too high, the resistivity decreases and a current flows, resulting in dielectric breakdown. Therefore, the magnitude of the polarization electrolysis is determined by the balance with the temperature.
【０００４】従来効果的であるとされた分極方法は、一
旦キューリー温度以上に加熱した後、電圧を印加した状
態で室温まで徐々に冷却させる方法である。しかし、こ
の方法では得られる圧電体の初期特性は高いものの、圧
電体を駆動させると、図１に示すように、分極処理によ
って一定方向にそろえられた分極が一部他の方向に向い
てしまい、その経時劣化を十分防止することができな
い。The polarization method considered to be effective in the past is a method of heating once to a Curie temperature or higher, and then gradually cooling to room temperature while applying a voltage. However, although the initial characteristics of the obtained piezoelectric body are high in this method, when the piezoelectric body is driven, the polarization aligned in a certain direction by the polarization processing is partially directed to another direction as shown in FIG. However, the deterioration with time cannot be sufficiently prevented.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、圧電セラミ
ックスの従来の分極方法の有する前記の如き欠点を解消
し、得られる圧電体において分極量の低下を防ぎ、駆動
時の耐久性を向上させる分極方法を提供しようとするも
のである。SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional polarization method for piezoelectric ceramics, prevents a decrease in the amount of polarization in the obtained piezoelectric material, and improves the durability during driving. It is intended to provide a polarization method.
【０００６】[0006]
【課題を解決するための手段】本発明者は、圧電セラミ
ックスの従来の分極方法の有する上記の問題点を解消す
べく鋭意研究を重ねた結果、圧電セラミックスを分極処
理した後、これを急激に冷却し、その後再び分極処理を
行うことにより、得られる圧電体の分極量の低下が抑制
されることを見出し、本発明を完成した。Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems of the conventional polarization method of piezoelectric ceramics. By cooling and then performing the polarization treatment again, it has been found that a decrease in the polarization amount of the obtained piezoelectric body is suppressed, and the present invention has been completed.
【０００７】すなわち、本発明の圧電セラミックスの分
極方法は、高電圧を印加した状態において(1) 圧電セラ
ミックスを、そのキューリー点の１／２の温度〜キュー
リー点以下の温度の範囲まで加熱し、この温度において
前記圧電セラミックスが分極飽和するに十分な時間保持
すること、(2) これを０℃以下の温度まで油冷により急
激に冷却し、この冷却状態において前記圧電セラミック
ス内に内部電荷が発生するに十分な時間保持すること、
そして(3) 前記圧電セラミックスをそのキューリー点の
１／２の温度〜キューリー点以下の温度の範囲まで加熱
し、この温度において前記圧電セラミックスが分極飽和
するに十分な時間保持すること、の工程からなることを
特徴とするものである。More specifically, the method for polarizing a piezoelectric ceramic according to the present invention comprises the steps of: (1) heating a piezoelectric ceramic to a temperature in a range of a temperature that is half the Curie point to a temperature that is equal to or lower than the Curie point in a state where a high voltage is applied; At this temperature, the piezoelectric ceramic is held for a time sufficient for polarization saturation. (2) This is rapidly cooled by oil cooling to a temperature of 0 ° C. or less, and internal charges are generated in the piezoelectric ceramic in this cooled state. Hold enough time to
And (3) heating the piezoelectric ceramic to a temperature in a range from a temperature at half the Curie point to a temperature equal to or lower than the Curie point, and maintaining the piezoelectric ceramic at this temperature for a time sufficient for polarization saturation of the piezoelectric ceramic. It is characterized by becoming.
【０００８】[0008]
【作用】図１に本発明の原理を示す。圧電体は分極処理
を行う前は、その自発分極の向きはランダムな方向を向
いており、この状態では圧電性を示さない。そこで本発
明の具体的な方法において、まず圧電セラミックスを、
高電圧を印加した状態においてそのキューリー点の１／
２の温度〜キューリー点以下の温度の範囲まで加熱し、
この圧電セラミックスを一定方向に分極させる。上記温
度範囲以外では自発分極が存在しなくなる。この温度に
圧電セラミックスを所定時間保持し、分極の向きをすべ
て一定方向にする。この時間は通常１〜５分で十分であ
る。FIG. 1 shows the principle of the present invention. Before the polarization process, the spontaneous polarization of the piezoelectric body is oriented in a random direction, and does not exhibit piezoelectricity in this state. Therefore, in the specific method of the present invention, first, the piezoelectric ceramic is
When a high voltage is applied, 1 /
Heating to the temperature range from the temperature of 2 to the temperature below the Curie point,
This piezoelectric ceramic is polarized in a certain direction. Outside the above temperature range, spontaneous polarization no longer exists. The piezoelectric ceramic is held at this temperature for a predetermined time, and the directions of polarization are all fixed. Usually, 1 to 5 minutes is sufficient.
【０００９】次いでこの分極させた圧電セラミックスを
０℃以下に急激に冷却し、この状態に所定時間保つ。す
ると、分極処理によって一定方向に向いた自発分極が再
びもとのランダムな方向に向く。このように内部電界が
急激に反転すると、それを抑えようとするように、圧電
セラミックス内に静電誘導により、自発分極とは逆の向
きに内部電荷が発生する。この冷却は通常シリコンオイ
ル中での油冷により行われる。冷却を保つ時間は、内部
電荷が発生するに十分な時間であり、通常１〜５分であ
る。Next, the polarized piezoelectric ceramic is rapidly cooled to 0 ° C. or lower, and is kept in this state for a predetermined time. Then, the spontaneous polarization oriented in a certain direction by the polarization processing is again oriented in the original random direction. When the internal electric field is suddenly inverted in this way, internal charges are generated in the piezoelectric ceramics in a direction opposite to the spontaneous polarization by electrostatic induction in the piezoelectric ceramics so as to suppress the inversion. This cooling is usually performed by oil cooling in silicone oil. The time for maintaining the cooling is a time sufficient for generating the internal charge, and is usually 1 to 5 minutes.
【００１０】その後、再び上記の加熱操作を行い、自発
分極の方向をそろえる。この際、上記冷却操作により生
じた内部電荷はすぐには消失せず内部に残っている。従
って、この加熱分極処理により方向がそろえられた自発
分極は内部電荷によりピンニングされ、劣化が防がれ
る。Thereafter, the above-mentioned heating operation is performed again to align the directions of spontaneous polarization. At this time, the internal charge generated by the cooling operation does not disappear immediately but remains inside. Therefore, the spontaneous polarization aligned in the direction by the heating polarization processing is pinned by the internal charge, thereby preventing deterioration.
【００１１】また、上記の加熱、冷却の工程を繰り返す
ことにより、より多くの内部電荷が圧電セラミックス内
に発生する。従って、この工程を繰り返すことにより、
108のレベルで駆動させるアクチュエータ等に適した、
より耐久性の高い圧電体が得られる。Further, by repeating the above heating and cooling steps, more internal charges are generated in the piezoelectric ceramic. Therefore, by repeating this process,
Suitable for actuators driven at 10 8 levels, etc.
A more durable piezoelectric body can be obtained.
【００１２】[0012]
【実施例】本発明を以下の実施例により更に詳細に説明
するが、本発明はこれらに制限されるものではない。The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
【００１３】圧電体の製造 まず、従来の方法によりＰＺＴ圧電体を製造した。すな
わち、ＰｂＯ、ＴｉＯ 2 及びＺｒＯ2 と微量元素を所定
量秤量し、湿式混合、仮焼、造粒、成形、焼成、加工、
及び電極形成の工程を行い、直径15mm、厚さ１mmのＰＺ
Ｔ圧電体を製造した。[0013]Manufacturing of piezoelectric body First, a PZT piezoelectric body was manufactured by a conventional method. sand
That is, PbO, TiO TwoAnd ZrOTwoAnd trace elements
Weighing, wet mixing, calcination, granulation, molding, firing, processing,
And electrode forming process, PZ of 15mm in diameter and 1mm in thickness
A T piezoelectric body was manufactured.
【００１４】分極処理 サンプル１ こうして得たＰＺＴ圧電体を、まず従来の方法により分
極処理した。すなわちＰＺＴ圧電体に１kv/mm の電圧を
加え、100 ℃のシリコンオイル中に入れ５分間保持し
た。これをサンプル１と呼ぶ。 Polarized Sample 1 The PZT piezoelectric material thus obtained was first polarized by a conventional method. That is, a voltage of 1 kv / mm was applied to the PZT piezoelectric body, and the PZT piezoelectric body was immersed in 100 ° C. silicone oil and held for 5 minutes. This is called Sample 1.
【００１５】サンプル２〜６ また上記のＰＺＴ圧電体を同様にして 200℃まで加熱
し、５分間保持し、次いでそれぞれを90℃、60℃、30
℃、０℃及び−20℃の温度のシリコンオイル中に入れ、
急激に冷却し、この温度に５分間保持し、次いで再び 2
00℃まで高め30秒間保持した。こうして得たサンプルを
それぞれサンプル２〜６と呼ぶ。 Samples 2 to 6 and the above PZT piezoelectric material were similarly heated to 200 ° C. and held for 5 minutes.
C, 0 ° C and -20 ° C in silicone oil,
Cool rapidly, hold at this temperature for 5 minutes, then again
The temperature was raised to 00 ° C. and held for 30 seconds. The samples thus obtained are referred to as samples 2 to 6, respectively.
【００１６】こうして製造したサンプルについて、その
変位を経時的にレーザ変位計により測定し、その変位特
性を求めた。変位特性は、初期変位（分極処理直後の変
位）に対する経時変化後の変位の割合である。この結果
を図２に示す。The displacement of the sample thus manufactured was measured over time by a laser displacement meter, and its displacement characteristics were determined. The displacement characteristic is a ratio of a displacement after a temporal change to an initial displacement (a displacement immediately after the polarization process). The result is shown in FIG.
【００１７】図２より明らかなように、従来の方法で分
極処理を行った圧電体（サンプル１）は時間と共にその
変位特性が著しく低下した。また、加熱後、90℃、60℃
及び30℃まで冷却した圧電体（それぞれサンプル２、３
及び４）は、この冷却により変位特性の低下が抑えられ
ているが、十分ではない。一方、０℃及び−20℃まで冷
却した圧電体（サンプル５及び６）は、ほとんどその変
位特性は低下しなかった。As is apparent from FIG. 2, the displacement characteristics of the piezoelectric body (sample 1) which has been subjected to the polarization treatment by the conventional method have significantly decreased with time. After heating, 90 ℃, 60 ℃
And a piezoelectric material cooled to 30 ° C (samples 2, 3 respectively)
In (4) and (4), although the deterioration of the displacement characteristics is suppressed by this cooling, it is not sufficient. On the other hand, the displacement characteristics of the piezoelectric bodies (samples 5 and 6) cooled to 0 ° C. and −20 ° C. hardly decreased.
【００１８】繰り返し分極処理 次に、ＰＺＴ圧電体を加熱し、次いで冷却する工程を複
数回繰り返すことにより、その効果を調べた。ＰＺＴ圧
電体を上記のようにして製造し、上記と同様にして加熱
し、次いで０℃まで冷却し、この加熱−冷却工程を１〜
５回繰り返し、最後に加熱し分極処理を行った。次いで
得られたサンプルを50枚積層し、0.5mmの積層体を形成
し、これに０〜800Vの電圧を加え、35MPa の初期圧力を
かけ駆動させ、変位量を測定しその耐久性を求めた。こ
の結果を図３に示す。The repeated poling then heated PZT piezoelectric, followed by repeating several times the step of cooling to examine the effects. A PZT piezoelectric body was manufactured as described above, heated in the same manner as above, and then cooled to 0 ° C.
The process was repeated five times, and finally, the substrate was heated and polarized. Next, 50 obtained samples were laminated to form a 0.5 mm laminated body, a voltage of 0 to 800 V was applied to the laminated body, an initial pressure of 35 MPa was applied to drive, the displacement was measured, and the durability was determined. . The result is shown in FIG.
【００１９】図３より明らかなように、繰り返し回数０
のサンプル、すなわち従来の圧電体は駆動後の変位特性
の低下が大きく、耐久性が十分ではない。一方、加熱−
冷却工程を行うことにより耐久性は向上し、これは繰り
返し回数が多いほど顕著である。As is apparent from FIG.
The sample (i.e., the conventional piezoelectric body) has a large decrease in displacement characteristics after driving, and thus has insufficient durability. On the other hand, heating
The durability is improved by performing the cooling step, and this is more remarkable as the number of repetitions increases.
【００２０】[0020]
【発明の効果】圧電体の分極処理時に、温度を０℃以下
の低温まで急激に低下させる本発明の方法により、圧電
体内に内部電荷を生じさせ、この内部電荷によって自発
分極をピンニングし、これによって分極量の低下を抑
え、圧電体の特性低下を抑制することができる。また、
圧電体の加熱−冷却工程を繰り返すことにより内部電荷
量を増加させ、それによりアクチュエータに適した駆動
耐久性の高い圧電体が得られる。According to the method of the present invention in which the temperature is rapidly lowered to a low temperature of 0 ° C. or less during the polarization treatment of the piezoelectric body, an internal charge is generated in the piezoelectric body, and the spontaneous polarization is pinned by the internal charge. Thereby, a decrease in the amount of polarization can be suppressed, and a decrease in the characteristics of the piezoelectric body can be suppressed. Also,
The amount of internal charge is increased by repeating the heating / cooling process of the piezoelectric body, whereby a piezoelectric body with high driving durability suitable for an actuator can be obtained.
【図１】従来の分極方法及び本発明の分極方法の原理を
示す図である。FIG. 1 is a diagram illustrating the principle of a conventional polarization method and the polarization method of the present invention.
【図２】各方法により分極処理した圧電体の変位特性の
経時変化を示すグラフである。FIG. 2 is a graph showing a change with time of a displacement characteristic of a piezoelectric body subjected to polarization processing by each method.
【図３】圧電体の耐久性に対する加熱−冷却工程の繰り
返しの効果を示すグラフである。FIG. 3 is a graph showing the effect of repeating a heating-cooling step on the durability of a piezoelectric body.
Claims (2)
高電圧を印加した状態において以下の工程： (1) 圧電セラミックスを、そのキューリー点の１／２の
温度〜キューリー点以下の温度の範囲まで加熱し、この
温度において前記圧電セラミックスが分極飽和するに十
分な時間保持すること、 (2) これを０℃以下の温度まで急激に冷却し、この冷却
状態において前記圧電セラミックス内に内部電荷が発生
するに十分な時間保持すること、そして (3) 前記圧電セラミックスをそのキューリー点の１／２
の温度〜キューリー点以下の温度の範囲まで加熱し、こ
の温度において前記圧電セラミックスが分極飽和するに
十分な時間保持すること からなることを特徴とする、圧電セラミックスの分極方
法。1. A method for polarizing a piezoelectric ceramic, comprising:
The following steps are performed in a state in which a high voltage is applied: (1) The piezoelectric ceramic is heated to a temperature in a range from a half temperature of its Curie point to a temperature equal to or lower than the Curie point. (2) Cooling this rapidly to a temperature of 0 ° C. or less, and in this cooling state, holding for a sufficient time to generate internal charges in the piezoelectric ceramics; and (3) Piezoelectric ceramics are の of Curie point
A method for polarizing a piezoelectric ceramic, comprising: heating the piezoelectric ceramic to a temperature in a range from the above temperature to a temperature equal to or lower than the Curie point, and holding the piezoelectric ceramic at this temperature for a time sufficient for polarization saturation of the piezoelectric ceramic.
及び(2) を複数回繰り返すことを特徴とする、圧電セラ
ミックスの分極方法。2. The method according to claim 1, wherein step (1) is performed.
And (2) are repeated a plurality of times.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21752593A JP3075033B2 (en) | 1993-09-01 | 1993-09-01 | Polarization method for piezoelectric ceramics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21752593A JP3075033B2 (en) | 1993-09-01 | 1993-09-01 | Polarization method for piezoelectric ceramics |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0774408A JPH0774408A (en) | 1995-03-17 |
| JP3075033B2 true JP3075033B2 (en) | 2000-08-07 |
Family
ID=16705615
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21752593A Expired - Fee Related JP3075033B2 (en) | 1993-09-01 | 1993-09-01 | Polarization method for piezoelectric ceramics |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3075033B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020130360A1 (en) * | 2018-12-21 | 2020-06-25 | 주식회사 메타바이오메드 | Method for polarizing piezoelectric element |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3724370B2 (en) * | 2000-12-26 | 2005-12-07 | 株式会社村田製作所 | Piezoelectric polarization method |
| RU2626304C1 (en) * | 2016-02-09 | 2017-07-25 | федеральное государственное автономное образовательное учреждение высшего образования "Южный федеральный университет" | Method of piezoelectric ceramic elements polarisation and device for its implementation |
-
1993
- 1993-09-01 JP JP21752593A patent/JP3075033B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2020130360A1 (en) * | 2018-12-21 | 2020-06-25 | 주식회사 메타바이오메드 | Method for polarizing piezoelectric element |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0774408A (en) | 1995-03-17 |
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