JPH0774408A - Polarization of piezoelectric ceramic - Google Patents
Polarization of piezoelectric ceramicInfo
- Publication number
- JPH0774408A JPH0774408A JP21752593A JP21752593A JPH0774408A JP H0774408 A JPH0774408 A JP H0774408A JP 21752593 A JP21752593 A JP 21752593A JP 21752593 A JP21752593 A JP 21752593A JP H0774408 A JPH0774408 A JP H0774408A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- polarization
- piezoelectric
- piezoelectric ceramics
- curie point
- 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)
Abstract
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。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 the steps of once polarizing the piezoelectric ceramic, rapidly cooling it, and then re-polarizing the piezoelectric ceramic. By this method, a piezoelectric element having high driving durability is provided. 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 A piezoelectric substance is a ferroelectric substance and must be polarized in order to utilize its piezoelectricity. The piezoelectric substance that has been subjected to the polarization treatment has a decreased polarization amount with time or after driving, and causes deterioration of characteristics, which is a serious problem when it is used for 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。The conventional general polarization treatment method is 80 to 120
It is performed by applying an electric field of 2 to 5 kV / mm in silicon oil at ℃. Here, the higher the temperature is, the lower the electric field can be polarized. However, if the temperature is too high, the resistivity decreases and a current flows, resulting in dielectric breakdown. Therefore, the magnitude of polarization electrolysis depends on the balance with 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。A polarization method which has been considered effective in the past is a method in which the material is once heated to a Curie temperature or higher and then gradually cooled to room temperature while a voltage is applied. However, although the piezoelectric element obtained by this method has a high initial characteristic, when the piezoelectric element is driven, as shown in FIG. 1, some of the polarizations aligned in a certain direction by the polarization process are oriented in other directions. However, the deterioration over 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。DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional polarization method for piezoelectric ceramics, prevents a decrease in polarization amount in the obtained piezoelectric body, and improves 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。The present inventor has conducted earnest research to solve the above-mentioned problems of the conventional polarization method for piezoelectric ceramics, and as a result, after the piezoelectric ceramics were polarized, the The present invention has been completed by finding that the decrease in the polarization amount of the obtained piezoelectric material can be suppressed by cooling and then performing the polarization treatment again.
【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。That is, the method of polarizing the piezoelectric ceramics of the present invention is as follows: (1) heating the piezoelectric ceramics in a state of applying a high voltage to a temperature range of a half of the Curie point to a temperature below the Curie point; Hold at this temperature for a sufficient time for polarization saturation of the piezoelectric ceramics, (2) cool it rapidly to a temperature of 0 ° C. or less by oil cooling, and generate internal charges in the piezoelectric ceramics in this cooling state. Hold for a sufficient time to
And (3) heating the piezoelectric ceramics to a temperature within a range from a temperature of 1/2 of the Curie point to a temperature equal to or lower than the Curie point, and holding at this temperature for a sufficient time for polarization saturation of the piezoelectric ceramics, 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。The principle of the present invention is shown in FIG. Prior to the polarization treatment, the piezoelectric body has a spontaneous polarization in a random direction, and does not exhibit piezoelectricity in this state. Therefore, in the concrete method of the present invention, first, the piezoelectric ceramic is
1 / of the Curie point under the condition that high voltage is applied
Heat to the temperature range from 2 to below Curie point,
This piezoelectric ceramic is polarized in a certain direction. The spontaneous polarization does not exist outside the above temperature range. The piezoelectric ceramics are kept at this temperature for a predetermined time so that all polarization directions are fixed. This time is usually 1 to 5 minutes.
【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 kept in this state for a predetermined time. Then, the polarization process causes the spontaneous polarization, which is oriented in a certain direction, to be oriented in the original random direction again. When the internal electric field is suddenly reversed in this way, an internal charge is generated in the piezoelectric ceramic in a direction opposite to the spontaneous polarization due to electrostatic induction so as to suppress it. This cooling is usually done by oil cooling in silicone oil. The time for keeping the cooling is a time sufficient to generate 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 heating operation is performed again to align the directions of spontaneous polarization. At this time, the internal charge generated by the cooling operation is not immediately lost but remains inside. Therefore, the spontaneous polarization whose direction is aligned by this heating polarization process is pinned by the internal charge, and deterioration is prevented.
【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。By repeating the heating and cooling steps described above, more internal charges are generated in the piezoelectric ceramics. Therefore, by repeating this process,
Suitable for actuators driven at 10 8 levels,
A piezoelectric body with higher durability 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。EXAMPLES The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention 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]Piezoelectric manufacturing First, a PZT piezoelectric body was manufactured by a conventional method. sand
Wachi, PbO, TiO 2And ZrO2And prescribed trace elements
Weighing, wet mixing, calcination, granulation, molding, firing, processing,
And the electrode formation process, PZ with diameter of 15mm and thickness of 1mm
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 placed in silicone oil at 100 ° C. and kept 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 The above PZT piezoelectric bodies were similarly heated to 200 ° C. and held for 5 minutes, and then they were heated to 90 ° C., 60 ° C. and 30 ° C., respectively.
Put in silicone oil at temperatures of ℃, 0 ℃ and -20 ℃,
Cool rapidly, hold at this temperature for 5 minutes, then re-apply 2
The temperature was raised to 00 ° C and held for 30 seconds. The samples thus obtained are called 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。With respect to the sample thus manufactured, its displacement was measured with time by a laser displacement meter, and its displacement characteristic was obtained. The displacement characteristic is the ratio of the displacement after the change over time to the initial displacement (the 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 characteristic of the piezoelectric body (Sample 1) which was polarized by the conventional method was significantly deteriorated with time. Also, after heating, 90 ℃, 60 ℃
And a piezoelectric body cooled to 30 ° C (samples 2, 3 respectively)
In 4 and 4), this cooling suppresses the deterioration of the displacement characteristics, but it is not sufficient. On the other hand, the piezoelectric bodies (Samples 5 and 6) cooled to 0 ° C. and −20 ° C. showed almost no deterioration in their displacement characteristics.
【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。 Repeated polarization treatment Next, the effect of the PZT piezoelectric material was investigated by repeating the steps of heating and then cooling the PZT piezoelectric material a plurality of times. The PZT piezoelectric body was manufactured as described above, heated in the same manner as described above, and then cooled to 0 ° C.
Repeated 5 times, and finally heated for polarization treatment. Then, 50 sheets of the obtained sample were laminated to form a 0.5 mm laminated body, a voltage of 0 to 800 V was applied to the laminated body, and an initial pressure of 35 MPa was applied to drive the laminated body, and the displacement amount was measured to determine its durability. . 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 clear from FIG. 3, the number of repetitions is 0.
The sample, that is, the conventional piezoelectric body, has a large decrease in displacement characteristics after driving, and its durability is not sufficient. On the other hand, heating-
By performing the cooling step, the durability is improved, and this becomes 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. As a result, it is possible to suppress a decrease in the amount of polarization and a decrease in the characteristics of the piezoelectric body. Also,
By repeating the heating-cooling process of the piezoelectric body, the amount of internal charge is increased, whereby a piezoelectric body having 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 showing a principle of a conventional polarization method and a 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 changes with time of displacement characteristics of a piezoelectric body polarized 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 the heating-cooling process on the durability of the 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 of polarizing piezoelectric ceramics, comprising:
The following steps are performed in the state where a high voltage is applied: (1) The piezoelectric ceramics are heated to a temperature range of a half of the Curie point to a temperature of the Curie point or lower, and the piezoelectric ceramics are polarized and saturated at this temperature. Holding for a sufficient time, (2) rapidly cooling this to a temperature of 0 ° C. or less, and holding for a sufficient time to generate an internal charge in the piezoelectric ceramic in this cooling state, and (3) above Piezoelectric ceramics with 1/2 of its Curie point
To a temperature below the Curie point, and holding at this temperature for a time sufficient to saturate the polarization of the piezoelectric ceramics.
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 the step (1)
A method for polarizing piezoelectric ceramics, characterized in that (2) and (2) are repeated multiple 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 true JPH0774408A (en) | 1995-03-17 |
| JP3075033B2 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 (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100418606B1 (en) * | 2000-12-26 | 2004-02-14 | 가부시키가이샤 무라타 세이사쿠쇼 | Piezoelectric element 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 |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102007526B1 (en) * | 2018-12-21 | 2019-08-06 | 주식회사 메타바이오메드 | Method for Polarizing Piezoelectric Element |
-
1993
- 1993-09-01 JP JP21752593A patent/JP3075033B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100418606B1 (en) * | 2000-12-26 | 2004-02-14 | 가부시키가이샤 무라타 세이사쿠쇼 | Piezoelectric element 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 |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3075033B2 (en) | 2000-08-07 |
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