JPH1045470A - Piezoelectric ceramics - Google Patents
Piezoelectric ceramicsInfo
- Publication number
- JPH1045470A JPH1045470A JP19927296A JP19927296A JPH1045470A JP H1045470 A JPH1045470 A JP H1045470A JP 19927296 A JP19927296 A JP 19927296A JP 19927296 A JP19927296 A JP 19927296A JP H1045470 A JPH1045470 A JP H1045470A
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric
- polarization
- domain wall
- angle
- polarization direction
- 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.)
- Pending
Links
- 239000000919 ceramic Substances 0.000 title claims abstract description 40
- 230000010287 polarization Effects 0.000 claims abstract description 54
- 239000013078 crystal Substances 0.000 claims description 9
- 230000005684 electric field Effects 0.000 abstract description 18
- 230000035939 shock Effects 0.000 abstract description 8
- 230000006866 deterioration Effects 0.000 abstract description 5
- 229910052573 porcelain Inorganic materials 0.000 abstract description 4
- 229910052688 Gadolinium Inorganic materials 0.000 abstract description 2
- 229910052779 Neodymium Inorganic materials 0.000 abstract description 2
- 229910052777 Praseodymium Inorganic materials 0.000 abstract description 2
- 229910052772 Samarium Inorganic materials 0.000 abstract description 2
- 229910052746 lanthanum Inorganic materials 0.000 abstract description 2
- 230000032683 aging Effects 0.000 description 20
- 238000000034 method Methods 0.000 description 13
- 238000005476 soldering Methods 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 230000002269 spontaneous effect Effects 0.000 description 5
- 238000004891 communication Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000004627 transmission electron microscopy Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000000992 sputter etching Methods 0.000 description 2
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- -1 MnO 2 Chemical class 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
- Transducers For Ultrasonic Waves (AREA)
- Apparatuses For Generation Of Mechanical Vibrations (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、例えばセラミック
フィルタ,セラミックレゾネータ,超音波応用振動子,
圧電ブザー,圧電点火ユニット,超音波モータ,圧電フ
ァン,圧電アクチュエータおよび加速度センサ,ノッキ
ングセンサ,AEセンサ等の圧電センサ等に適する圧電
セラミックスに関し、特にセルラー用のセラミックフィ
ルタとして最適な圧電セラミックスに関するものであ
る。The present invention relates to a ceramic filter, a ceramic resonator, an ultrasonic transducer,
Related to piezoelectric ceramics suitable for piezoelectric buzzers, piezoelectric ignition units, ultrasonic motors, piezoelectric fans, piezoelectric actuators and piezoelectric sensors such as acceleration sensors, knocking sensors, AE sensors, etc., and in particular to piezoelectric ceramics optimal as ceramic filters for cellular use. is there.
【0002】[0002]
【従来技術】従来から、セラミックフィルタ,セラミッ
クレゾネータ等の素子としては、PZT系の圧電磁器、
即ち、PbZrO3 −PbTiO3 を主成分とした磁器
が利用されており、これにNb2 O5 やMnO2 等の金
属酸化物、Pb( Nb2/3 Mg1/3 )O3 やPb( Nb
2/3 Mn1/3 )O3 等の複合ペロブスカイト酸化物を添
加したり置換することにより圧電特性の向上が図られて
いる。2. Description of the Related Art Conventionally, as elements such as ceramic filters and ceramic resonators, PZT-based piezoelectric ceramics,
That, PbZrO 3 -PbTiO 3 and ceramics as a main component is utilized, this Nb 2 O 5 or metal oxides such as MnO 2, Pb (Nb 2/3 Mg 1/3) O 3 and Pb ( Nb
By adding or replacing a composite perovskite oxide such as 2/3 Mn 1/3 ) O 3, the piezoelectric characteristics are improved.
【0003】ところで、PZT系の圧電セラミックスは
強誘電体に属しており、常温においては、結晶格子中の
電荷の重心がずれているために自発分極を有する。PZ
T系の圧電セラミックスは、このような結晶からなる焼
結粒子の集合体であって、固相反応によって作製された
場合、個々の焼結粒子も自発分極が一定方向をもった複
数のドメインから構成される。一つのドメイン内では、
自発分極が一定の方向に揃っているが、磁器全体として
は、自発分極の方向が等方的であるので圧電特性を示さ
ない。したがって、圧電特性を得るためには、圧電セラ
ミックスに外部から電場を印加して、個々のドメインの
自発分極の方向を揃える処理、すなわち、分極処理を施
す必要がある。一般に、分極処理を行った直後の圧電セ
ラミックスは圧電特性の劣化が起こりやすく、実際の使
用に耐えないので、予め、外部から熱などを加えること
により強制的に圧電特性を劣化させる処理を施す。この
エージング処理によって圧電セラミックスの特性を安定
化させている。Incidentally, PZT-based piezoelectric ceramics belong to ferroelectrics, and have spontaneous polarization at room temperature due to a shift in the center of gravity of charges in a crystal lattice. PZ
T-based piezoelectric ceramics are aggregates of sintered particles composed of such crystals. When produced by a solid-phase reaction, individual sintered particles are also formed from a plurality of domains in which spontaneous polarization has a certain direction. Be composed. Within one domain,
Although spontaneous polarization is aligned in a certain direction, the porcelain as a whole does not show piezoelectric characteristics because the direction of spontaneous polarization is isotropic. Therefore, in order to obtain piezoelectric characteristics, it is necessary to apply an electric field to the piezoelectric ceramics from the outside to perform a process of aligning the direction of spontaneous polarization of each domain, that is, a polarization process. In general, the piezoelectric ceramics immediately after the polarization processing are likely to deteriorate in the piezoelectric characteristics and cannot withstand actual use. Therefore, a process for forcibly deteriorating the piezoelectric characteristics by applying heat or the like from the outside is performed in advance. This aging process stabilizes the characteristics of the piezoelectric ceramic.
【0004】近年、通信機器を含めた電子装置の小型化
に伴い部品の表面実装化が急激に進んでいる。この表面
実装においては、リード線を有しない部品を基盤に仮り
実装し、この基盤をリフロー炉により加熱し半田付けす
るので、基盤に取り付けられる部品は、半田付けリフロ
ー処理によって、230℃前後の高い温度にさらされる
ことになる。これによる加熱が原因で、半田付けリフロ
ー処理の前後において、例えば、圧電素子については、
共振周波数が初期の周波数から外れるなどの問題が起こ
ることが多い。[0004] In recent years, surface mounting of components has been rapidly progressing along with miniaturization of electronic devices including communication devices. In this surface mounting, a component having no lead wire is temporarily mounted on a base, and the base is heated and soldered by a reflow furnace. You will be exposed to temperature. Due to the heating due to this, before and after the soldering reflow process, for example, for the piezoelectric element,
Problems such as the resonance frequency deviating from the initial frequency often occur.
【0005】したがって、高い信頼性と安定性が要求さ
れる通信機用の圧電フィルタなどに使用される圧電素子
に関しては、外部から熱衝撃を加えた場合でも、安定性
が高く、圧電特性の変化が非常に小さくなければならな
い。Therefore, a piezoelectric element used for a piezoelectric filter or the like for a communication device, which requires high reliability and stability, has high stability even when a thermal shock is applied from the outside, and changes in piezoelectric characteristics. Must be very small.
【0006】[0006]
【発明が解決しようとする課題】しかしながら、従来の
圧電セラミックスでは外部からの熱衝撃に弱く、リフロ
ー半田付け前後の圧電特性や共振周波数の変化が大き
く、実用上の問題となっていた。また、例えば、環境変
化の激しい車両搭載用通信装置などのフィルター等に用
いた場合、素子の特性変化によって安定した送受信がで
きなくなるという問題があった。However, conventional piezoelectric ceramics are susceptible to external thermal shock, and have large changes in piezoelectric characteristics and resonance frequency before and after reflow soldering, which poses a practical problem. Further, for example, when the filter is used for a filter of a vehicle-mounted communication device or the like in which the environment changes drastically, there has been a problem that stable transmission and reception cannot be performed due to a change in element characteristics.
【0007】[0007]
【課題を解決するための手段】本発明者等は、上記問題
について鋭意検討した結果、分極方向とドメイン壁との
なす角度の分布を0〜180°の範囲で求めたとき、4
0〜140°の範囲内で分布する割合が77%以上とな
るように、分極状態を制御することにより、高い安定性
を有するドメイン構造とすることができ、外部からの熱
衝撃に対しても特性劣化を抑制できることを見出し、本
発明に至った。The present inventors have conducted intensive studies on the above problem and found that when the distribution of the angle between the polarization direction and the domain wall was obtained in the range of 0 to 180 °, the distribution was 4 ° C.
By controlling the polarization state so that the proportion distributed in the range of 0 to 140 ° becomes 77% or more, a domain structure having high stability can be obtained, and even a thermal shock from the outside can be obtained. The present inventors have found that characteristic deterioration can be suppressed, and have reached the present invention.
【0008】即ち、本発明の圧電セラミックスは、分極
方向に対して0〜180°の角度で個々のドメイン壁を
有する結晶粒子の多結晶体であって、前記分極方向と前
記ドメイン壁とのなす角度が40〜140°である結晶
粒子の割合が77%以上のものである。That is, the piezoelectric ceramic of the present invention is a polycrystal of crystal grains having individual domain walls at an angle of 0 to 180 ° with respect to the polarization direction. The ratio of crystal grains having an angle of 40 to 140 ° is 77% or more.
【0009】[0009]
【作用】本発明の圧電セラミックスでは、リフロー半田
付け処理のように、圧電セラミックスに外部から熱衝撃
が加えられた場合でも、特性劣化が小さく、圧電特性が
初期特性から大きく変動することがない。According to the piezoelectric ceramics of the present invention, even when a thermal shock is applied to the piezoelectric ceramics from the outside as in the reflow soldering process, the characteristic deterioration is small and the piezoelectric characteristics do not largely change from the initial characteristics.
【0010】[0010]
【発明の実施の形態】本発明の圧電セラミックスは、分
極方向に対して0〜180°の角度で個々のドメイン壁
を有する結晶粒子の多結晶体で、前記分極方向と前記ド
メイン壁とのなす角度が40〜140°である結晶粒子
の割合が77%以上のものである。BEST MODE FOR CARRYING OUT THE INVENTION The piezoelectric ceramic of the present invention is a polycrystal of crystal grains having individual domain walls at an angle of 0 to 180 ° with respect to the polarization direction. The ratio of crystal grains having an angle of 40 to 140 ° is 77% or more.
【0011】このように、分極方向とドメイン壁とのな
す角度が40〜140°の範囲内のものを全体の77%
以上としたのは、77%よりも少ない場合には熱衝撃に
弱く、リフロー半田付け前後の圧電特性や共振周波数の
変化が大きく、また、環境変化の激しい車両搭載用通信
装置などのフィルター等に用いた場合、素子の特性劣化
が大きくなるからである。分極方向とドメイン壁とのな
す角度が40〜140°の範囲内のものは、全体の82
%以上であることが望ましい。As described above, the angle between the polarization direction and the domain wall within the range of 40 to 140 ° is 77% of the whole.
The reason for the above is that when less than 77%, the filter is susceptible to thermal shock, has large changes in the piezoelectric characteristics and resonance frequency before and after reflow soldering, and is used for filters of communication devices mounted on vehicles, which are subject to drastic environmental changes. This is because when used, the characteristics of the element are greatly deteriorated. When the angle between the polarization direction and the domain wall is in the range of 40 to 140 °, 82
% Is desirable.
【0012】ここで、圧電セラミックスの焼結粒子内の
ドメインの構造の観察は、焼結体の試料片を数十ミクロ
ンまで削って、イオンエッチングを行った後、試料薄片
のTEM(透過型電子顕微鏡)写真を撮影して行う。試
料薄片を作製する場合には、これによって試料のドメイ
ン構造が変化を受けないよう外部からの加熱を極力小さ
くする必要がある。Here, the structure of the domain in the sintered particles of the piezoelectric ceramic is observed by cutting a sample of the sintered body to several tens of microns, performing ion etching, and then performing TEM (transmission electron microscopy) of the sample thin. (Microscope) Take a picture. When preparing a sample slice, it is necessary to minimize external heating so that the domain structure of the sample is not changed by this.
【0013】分極軸の方向に対して平行である面を有す
る試料薄片のTEM写真を撮影すると、個々の焼結粒子
の内部には、ドメイン構造に起因する明瞭な筋状構造が
観察される。図1にこのドメイン構造の模式図を示す。
図1において、筋状構造の境界をドメイン壁1と呼ぶ
が、分極方向Aとドメイン壁1がなす角度θの分布を調
べた場合、分極処理前の試料ではドメイン壁がランダム
に存在するので、その角度分布は等方的となる。一方、
分極処理後の磁器に関しては、電界強度に応じてドメイ
ン壁が移動して配向性が高くなり、分極処理前の試料の
場合と比較すると、40〜140°の範囲に分布する割
合が高くなる。When a TEM photograph of a sample slice having a plane parallel to the direction of the polarization axis is taken, a clear streak structure due to a domain structure is observed inside each sintered particle. FIG. 1 shows a schematic diagram of this domain structure.
In FIG. 1, the boundary of the streak structure is referred to as the domain wall 1. When the distribution of the angle θ formed between the polarization direction A and the domain wall 1 is examined, the domain wall is randomly present in the sample before the polarization treatment. The angular distribution is isotropic. on the other hand,
With respect to the porcelain after the polarization treatment, the domain wall moves according to the electric field strength, and the orientation becomes higher. As compared with the case of the sample before the polarization treatment, the proportion distributed in the range of 40 to 140 ° becomes higher.
【0014】分極処理及びエージング処理を行った圧電
セラミックスに関して、分極軸方向とドメイン壁がなす
角度の分布を調べた場合、40〜140°の範囲が77
%以上になるようにドメイン壁の配向を制御すると、半
田付けリフロー処理などにより、高い温度にさらされた
場合でも、圧電特性が初期の特性から大きく変動せず、
安定性の高い圧電セラミックスを提供できる。When the distribution of the angle between the direction of the polarization axis and the domain wall of the piezoelectric ceramic subjected to the polarization treatment and the aging treatment is examined, the range of 40 to 140 ° is 77 °.
%, The piezoelectric characteristics do not fluctuate significantly from the initial characteristics even when exposed to high temperatures due to soldering reflow processing, etc.
A highly stable piezoelectric ceramic can be provided.
【0015】本発明の圧電セラミックスは、例えば、先
ず、組成式を(Pb1-x-y Ax By)a [{( Nb1/2
Yb1/2 )b (Nb1/2 Cr1/2 )c (Nb2/3 Co
1/3 )1-b-c }1-d Nbd ]e (Tif Zr1-f )1-e
O3 と表わした時、前記x,y,a,b,c,d,
e,fの値が、0<x、0<y、0<x+y≦0.1
2、0.970≦a≦1.030、0.100≦b≦
0.700、0.100≦c≦0.700、0≦d≦
0.170、0.030≦e≦0.200、0.480
≦f≦0.60を満足する圧電磁器を作製する。尚、こ
こで、AはCa,SrおよびBaのうちの少なくとも一
種、BはNd,Gd,La,PrおよびSmのうちの少
なくとも一種である。本発明は、上記組成の圧電磁器に
限定されるものではなく、PZT系の圧電磁器であれば
良い。[0015] The piezoelectric ceramic of the present invention, for example, first, the composition formula (Pb 1-xy A x B y) a [{(Nb 1/2
Yb 1/2 ) b (Nb 1/2 Cr 1/2 ) c (Nb 2/3 Co
1/3) 1-bc} 1- d Nb d] e (Ti f Zr 1-f) 1-e
When expressed as O 3 , the x, y, a, b, c, d,
When the values of e and f are 0 <x, 0 <y, 0 <x + y ≦ 0.1
2, 0.970 ≦ a ≦ 1.030, 0.100 ≦ b ≦
0.700, 0.100 ≦ c ≦ 0.700, 0 ≦ d ≦
0.170, 0.030 ≦ e ≦ 0.200, 0.480
A piezoelectric ceramic satisfying ≦ f ≦ 0.60 is manufactured. Here, A is at least one of Ca, Sr and Ba, and B is at least one of Nd, Gd, La, Pr and Sm. The present invention is not limited to the piezoelectric ceramic having the above composition, but may be any PZT piezoelectric ceramic.
【0016】そして、この圧電磁器について分極処理お
よびエージング処理を行う。分極処理は、磁器の分極が
飽和する時の電界(飽和電界)に対して75%以上の直
流電界、特には飽和電界を0.2〜1.0時間印加する
ことにより、PZT系圧電磁器の分極方向とドメイン壁
とのなす角度が40〜140°の範囲内で分布する割合
が高くなる。上記した組成式の圧電磁器では飽和電界は
80℃の条件下において1.5〜3kV/mmである。Then, a polarization process and an aging process are performed on the piezoelectric ceramic. The polarization treatment is performed by applying a DC electric field of 75% or more to the electric field (saturation electric field) when the polarization of the porcelain is saturated, in particular, by applying a saturation electric field for 0.2 to 1.0 hour, thereby obtaining a PZT piezoelectric ceramic. The ratio at which the angle between the polarization direction and the domain wall is distributed within the range of 40 to 140 ° increases. In the piezoelectric ceramic of the above composition formula, the saturation electric field is 1.5 to 3 kV / mm under the condition of 80 ° C.
【0017】この後、特性の安定化のためのエージング
処理を行う。このエージング処理は、キュリー温度の8
0〜97%、特には、87〜97%の温度で、0.5〜
3.0時間保持することにより、PZT系圧電磁器の分
極軸方向とドメイン壁とのなす角度の分布を0〜180
°の範囲で求めたとき、40〜140°の範囲内で分布
する割合を高くすることができる。上記した組成式の圧
電磁器ではキュリー温度は280〜330℃であるた
め、エージング温度は、220℃〜320℃、特には2
40〜320℃である。尚、分極処理を行った後のエー
ジング処理方法としては、熱によるエージング以外にも
圧力や電界印加によってエージング処理を行っても圧電
セラミックスのドメイン壁の配向を制御することが可能
であるが、熱によるエージングが最も望ましい。Thereafter, an aging process for stabilizing characteristics is performed. This aging treatment is performed at a Curie temperature of 8
At a temperature of 0-97%, especially 87-97%,
By holding for 3.0 hours, the distribution of the angle between the polarization axis direction of the PZT-based piezoelectric ceramic and the domain wall is reduced to 0 to 180.
When determined in the range of °, the distribution ratio in the range of 40 to 140 ° can be increased. In the piezoelectric ceramic of the above composition formula, the Curie temperature is 280 to 330 ° C., and the aging temperature is 220 ° C. to 320 ° C., particularly 2 ° C.
40-320 ° C. In addition, as an aging treatment method after performing the polarization treatment, it is possible to control the orientation of the domain walls of the piezoelectric ceramics by performing aging treatment by applying pressure or an electric field in addition to aging by heat. Aging is most desirable.
【0018】分極方向とドメイン壁とのなす角度の分布
を0〜180°の範囲で求めたとき、40〜140°の
範囲内で分布する割合が77%以上である本発明の圧電
セラミックスは、上記した条件における分極処理および
エージング処理により得られる。When the distribution of the angle between the polarization direction and the domain wall is determined in the range of 0 to 180 °, the ratio of the distribution in the range of 40 to 140 ° is 77% or more. It is obtained by the polarization treatment and the aging treatment under the above conditions.
【0019】[0019]
【実施例】出発原料として、PbO、ZrO2 、TiO
2 、Nb2 O5 、Yb2 O3 ,Cr2 O3 ,CoO,S
rCO3 ,La2 O3 の原料を用いて、組成式が(Pb
0. 96Sr0.03La0.01)1.00[{( Nb1/2 Yb1/2 )
0.263 (Nb1/2 Cr1/2)0.263 (Nb2/3 C
o1/3 )0.474 }0.88Nb0.12]0.06(Ti0.495 Zr
0. 505 )0.94 O3 となるように秤量し、該混合物をZ
rO2 ポールを用いたボールミルで12時間湿式混合し
た。EXAMPLES As starting materials, PbO, ZrO 2 , TiO
2, Nb 2 O 5, Yb 2 O 3, Cr 2 O 3, CoO, S
Using a raw material of rCO 3 and La 2 O 3 , the composition formula is (Pb
0. 96 Sr 0.03 La 0.01) 1.00 [{(Nb 1/2 Yb 1/2)
0.263 (Nb 1/2 Cr 1/2 ) 0.263 (Nb 2/3 C
o 1/3 ) 0.474 } 0.88 Nb 0.12 ] 0.06 (Ti 0.495 Zr
0.505) were weighed so that 0.94 O 3, the mixture Z
The mixture was wet-mixed in a ball mill using an rO 2 pole for 12 hours.
【0020】次いで、この混合物を脱水、乾燥した後、
大気中で1000℃で3時間仮焼し、この仮焼物を再び
ボールミルにより粉砕した。その後、この粉砕物に有機
バインダー(PVA)を混合して造粒した。得られた粉
末を1.5t/cm2 の圧力で直径23mm、厚さ2m
mの寸法からなる円板にプレス成形した。Next, after dehydrating and drying the mixture,
The calcined product was calcined at 1000 ° C. for 3 hours in the air, and the calcined product was pulverized again by a ball mill. Thereafter, an organic binder (PVA) was mixed with the pulverized product to granulate. The obtained powder was compressed under a pressure of 1.5 t / cm 2 to a diameter of 23 mm and a thickness of 2 m.
It was press-formed into a disk having a size of m.
【0021】さらに、これらの成形体をMgOなどから
なる容器内に密閉し、大気中1300℃で2時間の条件
で焼成し、試料A〜Eを得た。Further, these compacts were sealed in a container made of MgO or the like and fired at 1300 ° C. in the atmosphere for 2 hours to obtain samples A to E.
【0022】得られた圧電セラミックスに銀電極を焼き
付け、80℃のシリコンオイル中で、試料Aが1.4k
V/mm(飽和電界の70%)、試料Bは1.5kV/
mm(飽和電界の75%)、試料Cは1.7kV/mm
(飽和電界の85%)、試料Dは1.9kV/mm(飽
和電界の95%)、試料Eは2.0kV/mm(飽和電
界の100%)の直流電界を30分間印加して分極処理
した。尚、飽和電界は2.0kV/mmであった。A silver electrode was baked on the obtained piezoelectric ceramics, and a sample A was 1.4k in silicon oil at 80 ° C.
V / mm (70% of the saturation electric field), sample B was 1.5 kV /
mm (75% of the saturation electric field), sample C is 1.7 kV / mm
(85% of the saturation electric field), 1.9 kV / mm (95% of the saturation electric field) for sample D, and 2.0 kV / mm (100% of the saturation electric field) DC electric field for sample E for 30 minutes to perform polarization treatment. did. The saturation electric field was 2.0 kV / mm.
【0023】この分極処理した圧電セラミックスに対し
て、250〜295℃(キュリー温度310℃)の温度
で、1時間保持してエージング処理を施し、分極度が等
しい試料A〜Eを得た。試料Aは250℃(キュリー温
度の80%)、試料Bは270℃(キュリー温度の87
%)、試料Cは280℃(キュリー温度の90%)、試
料Dは292℃(キュリー温度の94%)、試料Eは2
95℃(キュリー温度の95%)でエージングした。試
料A〜Eの分極度は何れも等しく、Kp=45%であ
る。そして、試料A〜Eを数十ミクロンまで削って、イ
オンエッチングを行った後、試料薄片のTEM(透過型
電子顕微鏡)写真を撮影し、各試料のドメインの構造の
観察を20μm×20μmの面積で行った。この場合、
分極軸に対して一定角度(例えば40〜50°)のドメ
イン壁を有する領域の面積を求め、その全体面積に対す
る割合を求め、40〜140℃の範囲内のドメイン壁を
有する割合を求めた。尚、一結晶粒子内に異なる角度の
ドメイン壁を有する場合があるが、この場合はそれぞれ
の領域に分けて測定した。また、写真上にドメイン壁が
写らない場合もあるが、これについては全体面積に含め
なかった。The polarized piezoelectric ceramics were aged at a temperature of 250 to 295 ° C. (Curie temperature of 310 ° C.) for 1 hour to obtain samples A to E having the same degree of polarization. Sample A was 250 ° C. (80% of the Curie temperature), and Sample B was 270 ° C. (87% of the Curie temperature).
%), Sample C was 280 ° C. (90% of the Curie temperature), sample D was 292 ° C. (94% of the Curie temperature), and sample E was 2%.
Aged at 95 ° C. (95% of Curie temperature). Samples A to E have the same degree of polarization, and Kp = 45%. Then, the samples A to E are shaved to several tens of microns, and ion etching is performed. Then, a TEM (transmission electron microscope) photograph of the sample slice is taken, and the structure of the domain of each sample is observed in an area of 20 μm × 20 μm. I went in. in this case,
The area of a region having a domain wall at a fixed angle (for example, 40 to 50 °) with respect to the polarization axis was determined, the ratio to the entire area was determined, and the ratio having a domain wall in the range of 40 to 140 ° C. was determined. In some cases, domain walls having different angles are present in one crystal grain. In this case, the measurement was performed separately for each region. In some cases, the domain wall is not shown in the photograph, but this was not included in the total area.
【0024】次に、エージング処理の温度と、ドメイン
壁が分極方向に対して、40〜140°の範囲に分布す
る割合との関係について、図2に示した。また、半田付
けリフロー処理用の炉を使用した耐熱試験を行った。耐
熱試験は、プラスチックケースに入れた試料A〜Eを基
板に乗せ、ピーク温度240℃のリフロー炉を3回通過
させて行い、エージング温度と、半田付けリフロー処理
前後の機械的結合係数Kpの変化率との関係について、
図3に示した。Next, FIG. 2 shows the relationship between the temperature of the aging treatment and the ratio of the domain wall distributed in the range of 40 to 140 ° with respect to the polarization direction. In addition, a heat resistance test was performed using a soldering reflow furnace. The heat resistance test is performed by placing the samples A to E in a plastic case on a substrate and passing the sample three times through a reflow furnace having a peak temperature of 240 ° C., and changing the aging temperature and the mechanical coupling coefficient Kp before and after the solder reflow process. About the relationship with the rate,
As shown in FIG.
【0025】図2により、エージング温度が270℃以
上の場合には、分極軸方向とドメイン壁とのなす角度が
40〜140°の範囲内で分布する割合が77%以上で
あり、しかも、エージング温度が280℃以上の場合に
は82%以上となることが判る。そして、図3より、分
極方向とドメイン壁とのなす角度が40〜140°の範
囲内で分布する割合が77%以上の場合には機械的結合
係数Kpの低下率が2%以下であり、分極方向とドメイ
ン壁とのなす角度が40〜140°の範囲内で分布する
割合が82%以上の場合には機械的結合係数Kpの低下
率が1%以下であり、耐熱性に優れ、特性の変化が小さ
いことが判る。According to FIG. 2, when the aging temperature is 270 ° C. or more, the ratio of the angle formed between the polarization axis direction and the domain wall within the range of 40 ° to 140 ° is 77% or more, and the aging temperature is higher. It can be seen that when the temperature is 280 ° C. or more, it becomes 82% or more. From FIG. 3, when the ratio between the polarization direction and the domain wall distributed within the range of 40 to 140 ° is 77% or more, the reduction rate of the mechanical coupling coefficient Kp is 2% or less, When the angle formed between the polarization direction and the domain wall in the range of 40 to 140 ° is 82% or more, the reduction rate of the mechanical coupling coefficient Kp is 1% or less, and the heat resistance is excellent and the characteristics are excellent. Changes are small.
【0026】これと比較して、分極方向に対するドメイ
ン壁の40〜140°の角度範囲に分布する割合が72
%である試料Aでは、機械的結合係数Kpの低下率が
4.5%であり、半田付けリフロー処理前後の機械的結
合係数Kpの変化が大きいことが判る。In comparison with this, the ratio of the domain wall distributed in the angle range of 40 to 140 ° with respect to the polarization direction is 72%.
%, The rate of reduction of the mechanical coupling coefficient Kp is 4.5%, which indicates that the change in the mechanical coupling coefficient Kp before and after the reflow soldering process is large.
【0027】試料Aと試料Dついて、図4および図5に
ドメイン壁の角度分布を示した。エージング処理前の分
極度が高い試料Dの場合は、試料Aと比較して、40〜
140°の範囲に分布する割合が高くなり、全体のドメ
イン壁の86%がこの角度範囲に分布することが判る。FIG. 4 and FIG. 5 show the angular distribution of the domain wall for the samples A and D. In the case of the sample D having a high degree of polarization before the aging treatment, compared with the sample A, 40 to
It can be seen that the ratio of distribution in the range of 140 ° increases, and that 86% of the entire domain wall is distributed in this angle range.
【0028】したがって、飽和電界の70%で分極処理
し、エージング処理の温度を270℃以上に設定して、
分極方向に対するドメイン壁の40〜140°の角度範
囲に分布する割合を77%以上になるよう分極状態を制
御することにより、半田付けリフロー処理において、高
い温度にさらされても、特性の劣化が小さく、圧電特性
が初期の特性から大きく変動しない。一方、分極方向に
対するドメイン壁の40〜140°の角度範囲に分布す
る割合が77%より小さくすると、特性の劣化が2%よ
り大きくなり、実用的でない。Therefore, the polarization treatment is performed at 70% of the saturation electric field, and the aging treatment temperature is set to 270 ° C. or more.
By controlling the polarization state so that the ratio of the domain wall distributed in the angle range of 40 to 140 ° with respect to the polarization direction is 77% or more, the characteristics are not deteriorated even when exposed to a high temperature in the reflow soldering process. It is small, and the piezoelectric characteristics do not greatly change from the initial characteristics. On the other hand, if the proportion of the domain wall distributed in the angle range of 40 to 140 ° with respect to the polarization direction is smaller than 77%, the deterioration of the characteristics becomes larger than 2%, which is not practical.
【0029】[0029]
【発明の効果】本発明の圧電セラミックスによれば、半
田付けリフロー処理などのように外部から熱衝撃を加え
た場合でも、その前後において圧電特性が初期の特性か
ら大きく変動せず、高い信頼性と安定性を備えた圧電セ
ラミックスを提供できる。According to the piezoelectric ceramics of the present invention, even when a thermal shock is applied from the outside such as a reflow soldering process, the piezoelectric characteristics do not largely fluctuate from the initial characteristics before and after the thermal shock, and the reliability is high. And stable piezoelectric ceramics can be provided.
【図1】分極方向とドメイン壁のなす角度を説明するた
めの模式図である。FIG. 1 is a schematic diagram for explaining an angle between a polarization direction and a domain wall.
【図2】分極方向とドメイン壁のなす角度が、40〜1
40°の範囲に分布する割合をエージング処理の温度に
対して示した図である。FIG. 2 shows that the angle between the polarization direction and the domain wall is 40 to 1
It is the figure which showed the ratio distributed in the range of 40 degrees with respect to the temperature of an aging process.
【図3】ドメイン壁の配向を制御した圧電セラミックス
のリフロー試験前後における特性劣化を表わす図であ
る。FIG. 3 is a diagram showing characteristic deterioration of a piezoelectric ceramic in which the orientation of domain walls is controlled before and after a reflow test.
【図4】分極処理及びエージング処理を施した試料Aの
分極方向とドメイン壁のなす角度の分布を表わす図であ
る。FIG. 4 is a diagram showing a distribution of an angle between a polarization direction and a domain wall of a sample A subjected to a polarization process and an aging process.
【図5】分極処理及びエージング処理を施した試料Dの
分極方向とドメイン壁のなす角度の分布を表わす図であ
る。FIG. 5 is a diagram showing a distribution of an angle between a polarization direction and a domain wall of a sample D that has been subjected to a polarization process and an aging process.
1・・・ドメイン壁 A・・・分極方向 θ・・・分極方向とドメイン壁1がなす角度 1 ... domain wall A ... polarization direction θ ... angle between the polarization direction and domain wall 1
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 FI 技術表示箇所 H04R 17/00 H01L 41/18 101B 330 41/22 B ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification code Agency reference number FI Technical display location H04R 17/00 H01L 41/18 101B 330 41/22 B
Claims (1)
々のドメイン壁を有する結晶粒子の多結晶体であって、
前記分極方向と前記ドメイン壁とのなす角度が40〜1
40°である結晶粒子の割合が77%以上であることを
特徴とする圧電セラミックス。1. A polycrystal of crystal grains having individual domain walls at an angle of 0 to 180 ° with respect to the polarization direction,
The angle between the polarization direction and the domain wall is 40 to 1
A piezoelectric ceramic, wherein a ratio of crystal grains at 40 ° is 77% or more.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP19927296A JPH1045470A (en) | 1996-07-29 | 1996-07-29 | Piezoelectric ceramics |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19927296A JPH1045470A (en) | 1996-07-29 | 1996-07-29 | Piezoelectric ceramics |
Publications (1)
Publication Number | Publication Date |
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Family
ID=16405035
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Application Number | Title | Priority Date | Filing Date |
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JP19927296A Pending JPH1045470A (en) | 1996-07-29 | 1996-07-29 | Piezoelectric ceramics |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003023187A (en) * | 2001-07-10 | 2003-01-24 | Murata Mfg Co Ltd | Highly heat resistant piezoelectric element and piezoelectric device comprising it |
JP2005005698A (en) * | 2003-05-21 | 2005-01-06 | Jfe Mineral Co Ltd | Piezoelectric single crystal device and its manufacturing method |
WO2007029850A1 (en) * | 2005-09-05 | 2007-03-15 | Canon Kabushiki Kaisha | Epitaxial oxide film, piezoelectric film, piezoelectric film element, and liquid delivery head and liquid delivery apparatus using piezoelectric element |
US7622852B2 (en) | 2007-03-02 | 2009-11-24 | Canon Kabushiki Kaisha | Piezoelectric member, piezoelectric element, and liquid discharge head and liquid discharge apparatus utilizing piezoelectric element |
JP2010052977A (en) * | 2008-08-28 | 2010-03-11 | Kyocera Corp | Piezoelectric ceramic and piezoelectric element using the same |
-
1996
- 1996-07-29 JP JP19927296A patent/JPH1045470A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003023187A (en) * | 2001-07-10 | 2003-01-24 | Murata Mfg Co Ltd | Highly heat resistant piezoelectric element and piezoelectric device comprising it |
JP2005005698A (en) * | 2003-05-21 | 2005-01-06 | Jfe Mineral Co Ltd | Piezoelectric single crystal device and its manufacturing method |
WO2007029850A1 (en) * | 2005-09-05 | 2007-03-15 | Canon Kabushiki Kaisha | Epitaxial oxide film, piezoelectric film, piezoelectric film element, and liquid delivery head and liquid delivery apparatus using piezoelectric element |
US7804231B2 (en) | 2005-09-05 | 2010-09-28 | Canon Kabushiki Kaisha | Epitaxial oxide film, piezoelectric film, piezoelectric film element, liquid discharge head using the piezoelectric film element, and liquid discharge apparatus |
US7622852B2 (en) | 2007-03-02 | 2009-11-24 | Canon Kabushiki Kaisha | Piezoelectric member, piezoelectric element, and liquid discharge head and liquid discharge apparatus utilizing piezoelectric element |
JP2010052977A (en) * | 2008-08-28 | 2010-03-11 | Kyocera Corp | Piezoelectric ceramic and piezoelectric element using the same |
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